by John G. Connor, M.Ac., L.Ac. edited by Barbara Connor, M.Ac., L.Ac.
TABLE OF CONTENTS
1. Introduction
2. Setting Standards to Achieve Consistent Herbal Formulations
3. Systematic Reviews On Herb-Drug Interactions
4. Herb-Drug and Supplement-Drug Interactions
5. Interactions by Category of Drug
6. Interactions by Herb or Supplement
7. Towards a Better Understanding of Herbs and Drugs
8. Chemical Components of Herbs
9. References
10. Text Citations
1. INTRODUCTION
Barbara and I treat our patients using a combination of acupuncture and craniosacral therapy; and when indicated we use herbs and nutritional supplements to compliment our treatments. We have written this article/review so that you may be more informed of the possible interactions that might occur between the herbs or supplements and any drugs you may be taking. We hope you find it helpful.
In the last 10 to 20 years interest in natural therapies, especially herbal medicine has increased dramatically. Of all the alternative modalities herbal medicine is probably the most popular and the most ubiquitous. A study published four years ago found that 61% of elderly Hispanic and non-Hispanic white patients had used herbal remedies. An earlier study published in 1997 found that 34% of adult Americans had used herbal remedies. According to a national survey, about 60 million Americans over 18 years of age use herbal medicines to treat colds, burns, headaches, allergies, rashes, depression, diarrhea and menopause, among other conditions. The problem is that many people use prescription drugs concurrently with herbal remedies and as a result face possible health risks due to adverse reactions.[i] & [ii]
Recent surveys show that 18% of adults in the United States use prescription drugs concurrently with herbal or vitamin products, placing an estimated 15 million patients at risk of potential drug-supplement interactions.[iii] Indeed, half of the herbs taken by patients are not reported to their physicians. [iv]
2. SETTING STANDARDS TO ACHIEVE CONSISTENT HERBAL FORMULATIONS
Since the early 19th century attempts have been made to understand the actions and properties of traditional Chinese medicinal substances through scientific research. Due to the fact that herbs are composed of a multitude of ingredients whose interactions with the body are exceedingly complex a high level of sophistication of research methodology is necessary to describe these interactions. Only recently has such a rigorous methodology begun to be developed. [v]
Herbal medicines and natural supplements differ from synthetic drugs in the following ways:
Many herbs have no known active ingredients, and for most of the herbs of which some of the active ingredients are known little is understood of their pharmacokinetics. [vi]
Plants contain several hundred constituents and some of them are present at very low concentrations. In spite of the modern chemical analytical procedures available, only rarely do phytochemical investigations succeed in isolating and characterizing all secondary metabolites present in the plant extract.
Standardization, stability and quality control are feasible for patented supplement brands, but it is not as easy to achieve as it sounds. The availability and quality of raw materials can be problematic, especially during shortages.
Plant and supplement constituents vary considerably depending upon: the source and quality of the raw materials, the use of fresh plants, temperature, light exposure, the method of collecting, drying, packing, storage and transportation of the raw material, age and part of the plant collected as well as the possibility of contamination with microorganisms, heavy metals, and pesticides. No two brands are the same.
There are not many well-controlled double-blind clinical and toxicological studies to prove the efficacy and safety of herbal medicines. They have a wide range of therapeutic use and are suitable for chronic treatments. However, the occurrence of undesirable side effects seems to be less frequent with herbal medicines and they usually cost less than synthetic hormones or drugs. [vii]
What is a “Standardized Extract“? When you read the label on a bottle of herbs you will often see the words “Standardized Extract”. A standardized extract contains not only the active chemical constituent to which the extract has been standardized, but also the other components of the herb. Research has shown that using the isolated active component alone often does not produce the same therapeutic effect as does using a preparation containing all of the components together. This so-called synergistic action of herbs is not yet fully understood. Proponents of herbal remedies caution that in standardizing to one constituent resulting extracts may lose a proportion of benefit as compared with the whole plant. The use of standardized products, however, currently provides the greatest assurance of receiving an accurate, reliable dose of the active constituents of an herb, and of safely achieving the desired therapeutic effect.[viii] [ix]
3. SYSTEMATIC REVIEWS ON HERB-DRUG INTERACTIONS
In order to appreciate how modern science is approaching the question of herb-drug interactions we thought it would be instructive to include some scientific studies so you can see how scientists are tackling these issues. The gold standards for assessing efficacy and safety are large, well-designed, randomized controlled trials (RCTs) and systematic reviews. Systematic reviews require that all trials that meet specified criteria must be included in the review, regardless of the trial results. In the midst of the information explosion clinicians rank reviews as their most preferred source of new information. [x] Although there may indeed be more published systematic reviews on herb-drug interactions by now, when we conducted our Medline search we only found one. It is as follows:
Coon and Ernst (2002) conducted a systematic review on the adverse effects and drug interactions of Panax ginseng. Systematic searches were performed in five electronic databases and the reference lists of all papers located were checked for further relevant publications. Data from the clinical trials suggest that the incidence of adverse events with ginseng monopreparations is similar to that with placebo. The most commonly experienced adverse events are headache, sleep and gastrointestinal disorders. Combination products containing ginseng as one of several constituents have been associated with serious adverse events and even fatalities. Interpretation of these cases is difficult, as ingredients other than P. ginseng may have caused the problems. Possible drug interactions have been reported between P. ginseng and warfarin, phenelzine and alcohol. Collectively, these data suggest that P. ginseng monopreparations are rarely associated with adverse events or drug interactions. [xi]
4. HERB-DRUG AND SUPPLEMENT-DRUG INTERACTIONS
Useful Tips To Help Minimize Herb Drug Interactions
According to Subhuti Dharmananda, a highly respected Chinese herbalist, the nature of herb-drug interactions is not a chemical interaction between a drug and an herb component to produce something toxic. Instead, the interaction may involve having an herb component cause either an increase or decrease in the amount of drug in the blood stream. The following suggestions from Subhuti Dharmananda are useful to help avoid potential herb-drug interactions:
v Taking herbs at least 1 hrs apart from taking drugs is a very good idea.
v For example, tetracycline can bind with minerals in the herbs inhibiting their absorption resulting in low drug levels.
v Pectins, resins and fibers in herbs may bind several drugs inhibiting their absorption resulting in low drug levels. v Herbs can modify drug absorption and/or elimination. For example, saponins may improve absorption and elimination of drugs, altering the blood levels and rate of change of drug levels.
v Another good reason to take herbs at least 1 hours apart from drugs, preferably taking the drugs first, is so that drug metabolism is already underway by the time the herbs can inhibit enzyme systems. For example grapefruit juice and herbs such as angelica, that inhibit the CYP enzyme system, can result in much higher levels of drugs in the bloodstream and longer persistence of the drugs. Saponins in herbs may improve absorption and elimination of drugs, altering the blood levels and rate of change of drug levels.
v Avoid using herbs with strong laxative or diuretic action while using cardiac drugs. To compensate for mild diuretic or laxative treatments, consume high-potassium foods.
v When the drug therapy is already addressing a particular therapeutic goal, avoid adding a potent herbal therapy with the same goal. Intensify monitoring of blood conditions affected by the drugs.
v Learn the known drug reactions and take reasonable steps to avoid problematic herbs. For example, MAO inhibitors can cause hypertension when an ordinary food component, tyramine is ingested.
v Learn the known herb-drug interactions and avoid using the combinations, if necessary.
v For example, avoid mixing herbs or supplements and drugs that have similar actions. For example, gingko has blood-thinning properties and may heighten the effects of anticoagulant drugs.
v Conversely, you should avoid mixing herbs or supplements and drugs that have opposite actions. For example, ephedra can exacerbate high blood pressure and may cancel out the effects of antihypertensive drugs. [xii] [xiii] [xiv]
FA= Fetrow, Charles W., Pharm D. & Juan R. Avila, Pharm D, Professional’s Handbook of Complementary & Alternative Medicines[xvi]
HB= Harkness, Richard & Steven Bratman, M.D. Drug-Herb Interactions Bible [xvii]
LSR = Skidmore-Roth, Linda, Mosby’s Handbook of Herbs & Natural Supplements [xviii]
RR = Rountree, Robert, M.D., “Potential Herb-drug Interactions” Herbs for Health [xix]
SD = Dharmananda, Subhuti, Ph.D., “Responding to Concerns about Herb-Drug Interactions” [xx]
SDh = Dharmananda, Subhuti, Ph.D., “Checking for Possible Herb-Drug Interactions”[xxi]
v Iron supplements can interfere with the absorption of captopril and perhaps other ACE inhibitors. To minimize any potential problems take iron supplements and ACE inhibitors 2 to 3 hours apart. (HB)
v Licorice. Whole licorice can cause sodium retention and increase blood pressure, thus counteracting the intended effects of ACE inhibitors. DGL (deglycyrrhizinated licorice) is an altered form of the herb that should not cause these problems. (HB)
v Magnesium can interfere with absorption ACE inhibitors. To avoid this problem, magnesium should be taken at least 2 hours before or after taking these drugs. (BG)
v Potassium may interact with ACE inhibitors by causing irregular heart rhythm, muscle weakness, nausea, vomiting, irritability and diarrhea by increasing potassium levels in the blood even higher. (ACE inhibitors cause the body to retain more potassium than usual.) (HB)
Acetaminophen (Tylenol, Midol, Excedrin PM)
v Vitamin C, according to one study, at very high doses (3 g daily) might increase serum levels of acetaminophen. This could possibly allow the drug to accumulate to levels that may damage the liver. (BG & HB)
v Echinacea when combined with acetaminophen may result in increased incidences of hepatotoxicity and nephrotoxicity. [xxii]
v Kava when combined with acetaminophen may result in increased incidences of hepatotoxicity and nephrotoxicity. [xxiii]
v Ginkgo may interact with acetaminophen to increase the risk of bleeding. [xxiv]
Acne medication (Accutane)
v Vitamin A might interact with Accutane by increasing each other’s toxicity due to their structural similarities. (HB)
Alcohol
v Arginine when used in higher doses may increase the risk of gastric irritation when combined with alcohol. (BG)
v Betel Palm (Areca catechu) (pan parag) increases the effects of alcohol; do not use concurrently. (LSR)
v Hawthorn may increase the sedative effects of CNS depressants such as alcohol; avoid concurrent use. (LSR)
v Kava High doses of alcohol increased the effects and toxicity of kava in mice. (BG)
v Scutellaria baicalensis may increase sedation of CNS depressants; avoid concurrent use. (LSR)
v Valerian may enhance the effects of alcohol. (RR & BG)
v Valerian may increase the effects of CNS depressants; avoid concurrent use. (LSR)
All drugs
v Fenugreek may cause reduced absorption of all medications used concurrently. (LSR)
v Flax may cause a decrease in the absorption of all oral medications if taken concurrently with flax. (LSR)
v Ginger may increase absorption of all medications taken orally. (LSR)
v Pectin decreases absorption of all drugs, vitamins and minerals if taken concurrently. (LSR)
All oral drugs
v Flax may decrease absorption of all medications taken orally. (LSR)
v Ginger may increase absorption of all medications taken orally. (LSR)
v Marshmallow may reduce the absorption of oral medications; do not use concurrently. (LSR)
Alpha-adrenergic blockers (Cardura)
v Butcher’s Broom may decrease the action of alpha-adrenergic blockers, therefore avoid concurrent use. (LSR)
v Capsicum peppers may decrease the action of alpha-adrenergic blockers, therefore avoid concurrent use. (LSR)
v Yohimbe taken along with alpha-adrenergic blockers may result in increased toxicity, therefore avoid concurrent use. (LSR)
Anti-anginals
v Blue Cohosh may decrease the action of antianginals, causing chest pain so do not use concurrently. (LSR)
Anti-anxiety drugs (Benzodiazepines) (E.g., Xanax, Librium, Tranxene, Valium, Paxipam)
v Grapefruit juice slows the body’s normal breakdown of benzodiazepines, allowing them to build up to potentially dangerous levels in the blood. Therefore avoid grapefruit juice altogether if taking benzodiazepines. (LSR)
v Kava combined with alprazolam resulted in one case of a man being hospitalized for lethargy and disorientation. Experimental studies suggest that kava exerts is sedative effects similarly to benzodiazepines therefore combining kava with benzodiazepine drugs could result in “add-on” or excessive physical depression, sedation and impairment. Therefore avoid combining kava with benzodiazepines. (LSR)
v Melatonin may increase the anxiolytic effects of benzodiazepines; use together cautiously. (LSR)
v Ashwagandha, hops, lemon balm, passionflower, skullcap and valerian and other herbs with sedative effects might cause problems when combined with benzodiazepines. Avoid combining these herbs with benzodiazepines for this reason. (LSR)
Anti-arrhythmic drugs (Quinidine)
v Aloe can cause hypokalemia (lowered blood potassium levels) thereby enhancing the effects of anti-arrhythmic agents. (SD)
v Chinese rhubarb used chronically can cause hypokalemia (lowered blood potassium levels) and enhance the effects of anti-arrhythmic drugs. (SD & LSR)
v Goldenseal may increase the effects of anti-arrhythmic drugs. (LSR)
v Hawthorn may interact with or potentiate other cardiovascular drugs and such combinations should be used with caution. (BG)
v Licorice increases the cardiac effects of anti-arrhythmic drugs and therefore do not use concurrently. (LSR)
v Scrophularia nodosa may increase the effects of antiarrhythmics and beta-blockers; do not use concurrently. (LSR)
v Senna may interact with quinidine causing irregular heartbeats from low blood potassium because long-term use increases the loss of potassium from the stool as a result of laxative effect. (RR)
Anti-asthma drugs (theophylline)
v Arginine when used in higher doses may increase the risk of gastric irritation when combined with theophylline. (BG)
v Ipriflavone appears to slow the body’s normal breakdown of theophylline to inactive forms, allowing the drug to build up in the blood. This may increase the risk of toxic symptoms such as nervousness and even seizures. Therefore avoid using ipriflavone when taking theophylline. (HB)
v St. John’s wort lowers blood levels of theophylline causing a worsening of asthma symptoms. Therefore you should not combine St. John’s wort and theophylline. (RR & HB)
Antibiotics (fluoroquinolones, ciprofloxacin, nitrofurantoin, TMP-SMZ antibiotics such as Bactrim, Septra, Cotrim and Sulfatrim)
v Cranberry Theoretically some antibiotics could be inhibited by the reduced urinary pH caused by cranberry. (BG)
v Fennel appears to reduce blood levels of ciprofloxacin, possibly impairing its effectiveness. (HB)
v Iron supplements may inhibit the absorption of antibiotics in the tetracycline and quinolone families. Separating intake of the iron and drugs by at least 2 hours is likely to forestall any absorption problem. (BG)
v Magnesium can interfere with absorption of antibiotics in the tetracycline and fluoroquinolones families. To avoid this problem, magnesium should be taken at least 2 hours before or after taking these drugs. (BG)
v Zinc supplements can interfere with the absorption of tetracyclines, fluoroquinolones and penicillamine. (BG)
Anti-coagulants (Blood thinners) (Coumadin, Miradon, anisindione, dicumarol, heparin, warfarin)
Platelet Inhibitors (clopidogrel, ticlodipine)
v Alfalfa due to its high vitamin K content could, in theory, reduce the effectiveness of anticoagulants; avoid concurrent use. (HB)
v Arginine when used in higher doses may increase the risk of gastric irritation when combined with platelet inhibitors. (BG)
v Bilberry may increase the action of anticoagulants and antiplatelet agents; use caution if taking concurrently. (LSR)
v Chondroitin used with anticoagulants can cause increased bleeding. Do not use concurrently. (LSR)
v CoQ10 may decrease the action of anticoagulants; avoid concurrent use. (LSR)
v Cramp Bark (Black Haw) increases the action of anticoagulants; do not use concurrently. (LSR)
v Curcumin may result in an increased risk of bleeding if used with anticoagulants or NSAIDs; avoid concurrent use.(LSR)
v Dandelion leaf extract contains coumarins; therefore theoretically it could interact with anti-coagulants enhancing their effects. (BG)
v Dong quai (Angelica) interacts with warfarin to cause bleeding (SD) Dong Quai may interact with warfarin (BG) and it may increase the effects of antiplatelets and oral anticoagulants. Avoid the concurrent use of angelica with all anticoagulants. (LSR)
v Fenugreek taken concurrently with anticoagulants may cause an increased risk of bleeding. (LSR)
v Feverfew might potentially interact with anticoagulants because of its antiplatelet activity. (BG)
v Fish Oil Although fish oil does not appear to increase the bleeding complications caused by aspirin, interactions with anticoagulants such as warfarin have not been ruled out. (BG)
v Garlic interacts with warfarin to cause bleeding. (SD)
v Garlic interacts with warfarin causing increased bleeding by inhibiting platelet aggregation. (RR)
v Garlic has a blood thinning effect and therefore may be dangerous to take along with heparin. (HB)
v Garlic appears to possess anti-thrombotic activity and should be used with caution in patients on anticoagulants. (BG)
v Ginger should be used with care in patients using anticoagulants or antiplatelet agents because of its effects on platelet action. (BG)
v Gingko interacts with warfarin causing increased risk of bleeding by inhibiting platelet aggregation factor. (RR)
v Gingko has a blood thinning effect and therefore may be dangerous to take along with heparin (HB) and anticoagulants and antiplatelet agents. (LSR)
v Ginkgo is known to inhibit platelet activation factor and for this reason it is advisable to use caution when combining ginkgo with warfarin, heparin, aspirin or any other drugs with anticoagulant or antiplatelet effects. One case report suggests a probable interaction between ginkgo and aspirin. (BG)
v Ginseng may decrease the action of anticoagulants. (LSR)v
v Ginseng (Panax) interacts with warfarin to cause bleeding or to decrease effectiveness. (SD)
v Goldenseal may decrease the action of anticoagulants; do not use concurrently. (LSR)
v Green tea contains vitamin K, and large doses could potentially interfere with the effectiveness of anticoagulants.(BG)
v Horse Chestnut could theoretically interfere with anticoagulants because of the coumarins in it. (BG)
v Kelp used along with anticoagulants may pose an increased risk of bleeding; avoid concurrent use. (LSR)
v Nettle may decrease the effect of anticoagulants; avoid concurrent use. (LSR)
v OPCs (Grape Seed Extract) might (based on the activity of other flavonoids) potentiate anticoagulant and antiplatelet agents. (BG)
v Oxerutins theoretically might potentiate anticoagulants. (BG)
v Papain might potentiate anticoagulv ant and antiplatelet agents. (BG)
v Pau d’arco when combined with anticoagulants may result in an increased risk of bleeding; avoid concurrent use (theoretical). (LSR)
v Phosphatidylserine In vitro studies report that fatty acid esters of phosphatidylserine and phosphatidylethanolamine can synergistically stimulate the anticoagulant effect of heparin. (BG)
v Policosanol appears to potentiate the antiplatelet effects of aspirin. For this reason, caution should be exercised when combining policosanol with any antiplatelet or anticoagulant agent. (BG)
v Quercetin because of quercetin’s effects on platelet aggregation, interactions with antiplatelet and anticoagulant drugs could occur. (BG)
v Reishi (Ganoderma) could theoretically interfere with anticoagulants because of the constituents in it. (LSR)v v v Salvia (Danshen) interacts with warfarin to cause bleeding. (SD)
v Saw Palmetto may increase the anticoagulant effects of anticoagulants, antiplatelets and NSAIDs leading to increased bleeding time; avoid concurrent use. (LSR)
v St. John’s wort may interact with warfarin causing increased risk of blood clots by lowering blood levels of warfarin. (RR)
v Turmeric used along with anticoagulants may result in an increased risk of bleeding; avoid concurrent use. (LSR)
v Vinpocetine may impair the effectiveness of warfarin. (BG)
v Vitamin A may increase the anticoagulant effects of warfarin. (BG)
v Vitamin C might reduce the effects of warfarin and heparin according to weak evidence. (BG)
v Vitamin E might potentiate anticoagulant or antiplatelet medications based on its anticoagulant properties. (BG)
v Vitamin K antagonizes the action of warfarin. (BG)
v White willow also known as willow bark contains a substance that is converted by the body into a Salicylate similarto aspirin. Since combining aspirin with heparin increases the risk of abnormal bleeding, it would be advisable not to combine white willow with heparin. (HB)
Anti-convulsant drugs (phenobarbital, Phenytoin, Dilantin, Primidone, Mysoline, Carbamazepine, Valproic Acid, Keppra, Neurontin, Trileptal, Klonopin)
v Borage and Evening Primrose Oil should not be used with anticonvulsants because they may lower the seizure threshold. [xxv]
v Folate (Folic Acid) may increase seizures in individuals with epilepsy and may interfere with phenytoin therapy. (BG)
v Ginkgo components may decrease the anticonvulsant effect; avoid concurrent use. (LSR)
v Ginseng may provide an additive anticonvulsant action (theoretical). (LSR)
v Glutamine Theoretically, high doses of glutamine may overwhelm anticonvulsant drugs and pose a risk to individuals with seizure disorders because many of them work by blocking glutamine stimulation in the brain. (BG)
v Hawthorn may increase the sedative effects of CNS depressants such as barbiturates; avoid concurrent use. (LSR)
v Kava taken with barbiturates may result in increased sedation. (LSR)
v Lemon Balm may increase the sedative effects of barbiturates and CNS depressants. (LSR)
v Magnesium can interfere with absorption of phenytoin. To avoid this problem, magnesium should be taken atleast 2 hours before or after taking these drugs. (BG)
v Sage may decrease the action of anticonvulsants; avoid concurrent use (theoretical). (LSR)
v Scutellaria baicalensis may increase sedation of CNS depressants; avoid concurrent use. (LSR)
v Valerian may increase the effects of CNS depressants; avoid concurrent use. (LSR)
v Vitamin B3 (Niacin) might increase serum levels of anticonvulsant medications including carbamazepine and primidone, possibly requiring reduction in drug dosage. (BG)
Anti-depressants (MAO inhibitors, phenelzine sulfate, amitriptyline, Elavil, Wellbutrin, Celexa, Prozac, Zoloft, Paxil, Effexor)
v Cranberry Blood levels of antidepressants can be reduced by excessive use of cranberry juice. (BG)
v Ginseng may interact with phenelzine sulfate to cause manic episodes and headaches. (SD)
v Hops may cause increased CNS effects when taken concurrently with antidepressants. (LSR)
v Sam-e combined with antidepressants may lead to serotonin syndrome*; do not use concurrently. (LSR) * (See serotonin syndrome below for complete description.)
v St. John’s wort interacts with phenylpiperazine antidepressants such as nefazodone and trazodone (RR) causing serotonin syndrome. * (Serotonin syndrome is a toxic reaction requiring immediate medical attention and is associated with too much serotonin. Symptoms may include anxiety, restlessness, confusion, weakness, tremor, muscle twitching or spasm, high fever, profuse sweating and rapid heart beat.)
v St. John’s wort may cause serotonin syndrome* when used with antidepressants. Do not use concurrently. (LSR) * (See serotonin syndrome above for complete description.)
v St. John’s wort interacts with amitriptyline (and theoretically other tricyclic anti-depressants) causing a worsening of depression. (RR)
Anti-diabetic drugs (Amaryl, Glucophage, Avandia, Orinase)
v Basil may increase the hypoglycemic effects of insulin; do not use concurrently. (LSR)
v Bilberry leaves may significantly decrease blood sugar levels; monitor carefully (Brinter1998). (LSR)
v Chromium may reduce the action of antidiabetics. (LSR)
v Dandelion may increase the effects of insulin; avoid concurrent use. (LSR)
v Ephedra may cause an increase in blood glucose levels; monitor carefully. (LSR)
v Fenugreek may cause acute hypoglycemia in diabetic patients who use insulin or other hypoglycemic drugs.
v Ginseng (American and Asian) interacts with hypoglycemic agents for diabetes causing hypoglycemia and shockbecause the ginsenosides in ginseng lower blood sugar. (RR)
v Glucosamine may theoretically increase the effects of antidiabetics. (LSR)
v Gotu kola may decrease the effectiveness of antidiabetics; do not use concurrently. (LSR)
v Gymnema may possibly increase the action of insulin, other hypoglycemic or oral antidiabetic drugs, leading to hypoglycemic reactions (theoretical). (BG & LSR)
v Horse chestnut may increase the hypoglycemic effects of diabetic medications. (LSR)
v Myrrh taken along with antidiabetics may cause increased hypoglycemic effects; avoid concurrent use. (LSR)
v Siberian ginseng may increase levels of antidiabetic drugs; avoid concurrent use. (LSR)
Anti-diabetic drugs (oral) (Amaryl, Glucophage, Avandia, Orinase)
v Basil may increase the hypoglycemic effects of oral antidiabetics; do not use concurrently. (LSR)
v Bilberry may increase hypoglycemia; use caution if taking concurrently with oral antidiabetics. (LSR)
v Co Q10 It is possible that individuals taking oral hypoglycemics might need to reduce their dosage. (BG)
v Coriander may increase the effects of oral antidiabetic agents; use together cautiously. (LSR)
v Dandelion may increase the effects of insulin; avoid concurrent use. (LSR)
v Ephedra may cause an increase in blood glucose levels if used along with antidiabetic agents; monitor carefully. (LSR)
v Fenugreek may cause acute hypoglycemia in diabetic patients who use insulin or other hypoglycemic drugs. (BG)
v Flaxseed supplementation (as with other high-fiber foods) could potentially require a reduction in hypoglycemic drug dosage. (BG)
v Garlic has hypoglycemic effects; therefore the dosages of oral antidiabetics may need to be adjusted if taken concurrently. (LSR)
v Ginseng is known to decrease blood glucose levels and therefore it may increase the hypoglycemic effect of antidiabetics; avoid concurrent use. (LSR)
v Gotu kola may decrease the effectiveness of antidiabetics; avoid concurrent use. (LSR)
v Gymnema may possibly potentiate the action of insulin or other hypoglycemic drugs, leading to hypoglycemic reactions. (BG)
v Magnesium might increase the effectiveness of oral hypoglycemics in the sulfonylurea family, potentially creating a risk of hypoglycemia. (BG)
v Vitamin E might enhance insulin sensitivity in individuals with type 2 diabetes. This could lead to a risk of hypoglycemia and may warrant adjustment of oral hypoglycemic medications. (BG)
Anti-fungal drugs (itraconazole, Sporanox)
v Goldenseal may slow the metabolism of azole antifungals; avoid concurrent use. (LSR)
v Grapefruit juice causes decreased absorption of itraconazole, which might result in treatment failure. It is thus best to avoid taking grapefruit juice along with itraconazole. (HB)
v Licorice may increase the levels of azole antifungals; avoid concurrent use. (LSR)
Anti-hypertensive drugs (clonidine, Cardura, methyldopa, reserpine, Flomax)
v Black cohosh has weak indications of potential interactions with anti-hypertensive medications. (BG) It may increase the action of antihypertensives; avoid concurrent use. (LSR)
v Coenzyme Q10 can prolong the effects of the antihypertensives enalapril and nitrendipine without increasing their maximum hypotensive effect according to the suggestions of one animal study. (BG)
v Dandelion may increase the effects of antihypertensives; avoid concurrent use. (LSR)
v Goldenseal may worsen high blood pressure. (SDh)
v Hawthorn may interact with or potentiate other cardiovascular drugs and such combinations should be used with caution. (BG)
v Hawthorn may increase hypotension when used with antihypertensives; avoid concurrent use. (LSR)
v Licorice may cause increased hypokalemia if used with antihypertensives; do not use concurrently. (LSR)
v Yohimbe should not be combined with antihypertensive agents. (BG)
Anti-psychotic drugs (phenothiazines) (chlorpromazine, Thorazine, Haldol, lithium, Zyprexa, thioridazine, Mellaril)
v Cranberry Blood levels of antipsychotics can be reduced by excessive use of cranberry juice. (BG)
v Dandelion One case report suggests that individuals on lithium should avoid use of herbs with diuretic properties (such as dandelion) due to risk of dehydration and subsequent lithium toxicity. (BG)
v Ephedra may cause tachycardia in used with phenothiazines; do not use concurrently. (LSR)
v Evening Primrose Oil may cause seizures if used with phenothiazines; do not use concurrently. (LSR)
v Kava Case reports suggest that kava might increase the risk of dystonic reactions in individuals on phenothiazines. (BG)
v Kava may result in neuroleptics movement disorders if taken along with antipsychotics. (LSR)
v Nettle when combined with lithium may result in dehydration, lithium toxicity. (LSR)
v Phenylalanine (D or DL) might increase the risk of developing tardive dyskinesia when combined with antipsychotic drugs. (BG)
v Yohimbe should not be combined with phenothiazines. (BG)
Yohimbe may result in increased toxicity if used with phenothiazines; avoid concurrent use. (LSR)
Anti-retroviral drugs (Indinavir)
v St. John’s wort may interact with Indinavir causing decreased drug effectiveness and worsening of HIV infection by lowering blood levels of the drug. (SD)
Beta-Blockers (metoprolol, Lopressor, propranolol hydrochloride, atenolol)
v Betel Palm (Areca catechu) (pan parag) increases the effects of beta-blockers; do not use concurrently. (LSR)
v Ephedra causes increased hypertension when used with beta-blockers; avoid concurrent use. (LSR)
v Scrophularia ningpoensis (Figwort) may increase the effects of beta-blockers; do not use concurrently. (LSR)
Calcium channel blockers
v Grapefruit juice impairs the breakdown of calcium channel blockers allowing them to build up to potentially dangerous levels in the blood. Avoid grapefruit juice altogether if taking calcium channel blockers. (HB)
v Vitamin D combined with calcium supplements might interfere with calcium channel blockers. (BG)
Congestive heart failure drugs (cardiac glycosides such as Digoxin and Digitoxin,)
v Aloe can cause hypokalemia (lowered blood potassium levels) thereby enhancing the effects of cardiac glycosides. (SD)
v Betel Palm (Areca catechu) (pan parag) increases the effects of cardiac glycosides; do not use concurrently.(LSR)
v Chinese rhubarb used chronically can cause hypokalemia and enhance the effects of cardiac glycosides. (SD)
v The action of figwort may be increased by cardiac glycosides; do not use concurrently. (LSR)
v Ginseng (Siberian) may increase levels of cardiac glycosides; avoid concurrent use. (LSR)
v Hawthorn may interact with or potentiate other cardiovascular drugs and such combinations should be used with caution. (BG)
v Hawthorn may increase the effects of cardiac glycosides; monitor concurrent use carefully. (LSR)
v Licorice can interact with digitalis or other cardiac glycosides causing increased sensitivity. (SD)
v Licorice used along with cardiac glycosides may cause increased toxicity and increased hypokalemia; do not use concurrently. (LSR)
v Ma-huang can interact with cardiac glycosides or halothane to produce cardiac arrhythmia. (SD)
v Ma huang may interact with Digoxin causing irregular heartbeats by overriding the drug’s ability to even out irregular heartbeats. (RR)
v Senna may interact with digoxin causing irregular heartbeats from low blood potassium because long-term use increases the loss of potassium from the stool as a result of laxative effect. (RR)
v St. John’s wort interacts with digoxin-based drugs and can theoretically lead to a worsening of heart failure and irregular heartbeats. (RR)
Corticosteroids (cortisone, prednisone)
v Arginine when used in higher doses may increase the risk of gastric irritation when combined with corticosteroids. (BG)
v Chinese rhubarb used chronically can cause hypokalemia (lowered blood potassium levels) and enhance the effects of corticosteroids. (LSR)
v Licorice can interact with corticosteroids causing salt and water retention, lowered blood potassium, elevated blood pressure, elevated blood sugar and excessive immune suppression by inhibiting an enzyme that breaks down corticosteroids, thus increasing blood levels of the drug. (RR)
v Licorice can interact with corticosteroids to enhance their effects. (SD)
v Licorice may increase the effects of corticosteroids; avoid concurrent use. (LSR)
v Perilla may augment the effect of corticosteroids; avoid concurrent use. (LSR)
v Selenium deficiency may result from treatment with corticosteroids. (BG)
v Senna may interact with corticosteroids causing irregular heartbeats from low blood potassium because long-term use increases the loss of potassium from the stool as a result of laxative effect. (RR)
Decongestants and Antihistamines (phenylpropanolamine, pseudoephedrine, Benadryl, Allegra, Claritin, Phenergan)
v Ephedra may interact with decongestants causing high blood pressure and rapid or irregular heartbeats by magnifying the stimulating effects of these drugs. (RR)
Diuretics
v Licorice can interact with diuretics negating the blood-pressure lowering effect of these drugs and causing irregular heartbeats from increased potassium loss. Licorice mimics the effect of aldosterone, an adrenal hormone that causes sodium retention and potassium loss. (RR)
v Senna may interact with diuretics causing irregular heartbeats from low blood potassium because long-term use increases the loss of potassium from the stool as a result of laxative effect. (RR)o
Thiazide Diuretics such as Diuril.
v Chinese rhubarb used chronically can cause hypokalemia (lowered blood potassium levels) and enhance the effects of thiazide diuretics. (LSR)
v Licorice can interact with thiazide diuretics enhancing their effects. (SD)
v Vitamin D combined with calcium and thiazide diuretics can lead to hypercalcemia. (BG) o
Potassium-sparing Diuretics such as Aldactone, Amiloride, Midamor, triamterene, Enduronv
v Licorice should never be taken along with potassium sparing diuretics. Potassium-sparing diuretics such as Amiloride and Aldactone cause the body to retain potassium whereas licorice has the opposite effect causing the body to lose potassium and thus directly counteracts the effect of these drugs. (HB)
v Licorice may cause increased hypokalemia if used with diuretics (amiloride, triamterene); avoid concurrent use. (LSR)v Use caution supplementing with magnesium if taking amiloride, because amiloride may reduce urinary magnesium excretion. (BG)
v Potassium supplements taken along with potassium-sparing diuretics could raise your potassium levels too high resulting in nausea, vomiting, irritability, diarrhea and changes in heart function. (HB)o
Loop Diuretics such as furosemide (Lasix), bumetanide, ethacrynic acid or torsemide.
v Licorice taken in high dosages or used long-term causes low blood levels of potassium. Loop diuretics also cause potassium loss. Therefore one should avoid taking licorice with loop diuretics. DGL licorice should not affect potassium levels and so should not pose a danger for loop diuretic users. (HB)
Estrogen
v Black cohosh may alter the effects of other hormone replacement therapies; use together cautiously. (LSR)
v Chasteberry (Chaste tree) could conceivably interact with bromocriptine or other drugs intended to affectprolactin levels. For similar reasons, the herb is usually not given along with exogenous estrogen or progesterone or other treatments with endocrine activity. (BG)
v It is theoretically possible that the phytoestrogenic action of hops could have an impact on hormonal therapies such as estrogen. (BG & LSR)
v St. John’s wort may interact with estrogen causing breakthrough bleeding. (RR)
Immunosuppressants (cyclosporine)
v Aloe may conceivably interfere with the action of immune suppressant drugs because of the known immunomodulatory effects of acemannan (a polysaccharide derived from aloe). (BG)
v Astragalus can interact with cyclosporine, azathioprine and methotrexate to impair intended immunosuppressive effects. (SD)
v Curcumin may decrease the effectiveness of immunosuppressants; avoid concurrent use. (LSR)
v Echinacea may decrease the effects of immunosuppressants and should not be used immediately before, during or after transplant surgery. (LSR)
v Eleutherococcus (Siberian Ginseng) Based on its purported immunomodulatory actions it might interfere with the action of immunosuppressive drugs. (BG)
v Ginseng may diminish the effect of immunosuppressants; do not use immediately before, during or after transplant surgery. (LSR)
v Goldenseal might inhibit CYP3A4 (BG) thereby causing a decrease of cyclosporine leading to transplant rejection. (CYP is the abbreviation for cytochrome P450 enzymes. The CYP is usually followed by an Arabic numeral, a letter and another Arabic numeral e.g. CYP 2D6. These enzymes are found in and on the smooth endoplasmic reticulum of liver and other cells and are responsible for a large number of drug biotransformation reactions.)
v Grapefruit juice slows the body’s normal breakdown of cyclosporine, allowing it to build up to potentially excessive levels in the blood. If you take cyclosporine the safest approach is to avoid grapefruit juice altogether. (HB)
v Ipriflavone Based on the observed lymphopenic effects of ipriflavone in which it causes decreased serumlymphocyte levels, it should be used with caution in individuals taking immunosuppressant drugs. (BG)
v Maitake mushroom may decrease the effects of immunosuppressants; do not use immediately before, during or after transplant surgery. (LSR)
v Red yeast rice interacts with cyclosporine increasing the risk of CK elevation and rhabdomyolysis. (Prasad et al 2002) (FA)
v Schisandra may decrease the effectiveness of immunosuppressants; avoid use before, during or after transplant surgery. (LSR)
v St. John’s wort can interact with cyclosporine causing transplant rejection (Ernst 2002) so absolutely avoid taking St. John’s wort with cyclosporine. (RR)
Levodopa (Carbidopa, Sinemet)
v 5-HTP may combine with carbidopa to cause a scleroderma-like condition in which the skin becomes hard and tight (HB & BG)
v Iron may interfere with the absorption of both levodopa and carbidopa by binding to them. You should separate the times you take iron and these drugs by as long as possible. (HB)
v Kava might interfere with the action of dopamine in the body at least partially neutralizing the effects of levodopa. (HB)
v Policosanol might potentiate the action of levodopa, causing increased dyskinesias. (BG)
v Vitamin B6 in higher doses can reduce the therapeutic effects of levodopa. Fortunately, however, since most people with Parkinson’s disease use a combination of levodopa and carbidopa rather than levodopa alone, carbidopa neutralizes the effect of vitamin B6 on levodopa making the interaction with B6 unlikely in practice. (HB)
MAO Inhibitors (Monamine Oxidase Inhibitors) (phenelzine, tranylcypromine)
v Asian Ginseng causes headache, insomnia, trembling and other symptoms when taken along with phenelzine, so it is best to avoid taking these two substances together until more is known. (HB)
v Betel Palm (Areca catechu) (pan parag) increases the effects of MAO inhibitors; do not use concurrently. (LSR)
v Butcher’s Broom may increase the action of MAO inhibitors and precipitate a hypertensive crisis so do not useconcurrently. (LSR)
v Ginkgo may increase the action of MAOIs if taken concurrently (theoretical). (LSR)
v Ginseng use along with MAOIs may result in manic-like syndrome. (LSR)
v Green tea The caffeine in green tea could cause significant interactions with MAO inhibitors. (BG)
v Ma-huang can interact with MAO inhibitors causing hypertension. (SD)
v Ma huang may interact with MAO inhibitors causing extreme high blood pressure by magnifying the stimulating effects of these drugs. (RR)
v Ma huang when combined with MAO inhibitors such as phenelzine (Nardil) may lead to severe tachycardia or hypertension and may be fatal (BG)
Methotrexate
v Echinacea may cause inflammation of the liver if used with methotrexate. (SDh & Miller, 1998)
v Folate (Folic Acid) may safely reduce some of the side effects of methotrexate (particularly elevated liver enzymes) when taken at the same time. (BG)
v Potassium citrate may lead to decreased blood levels and therapeutic effects of methotrexate. Avoid use altogether except under medical supervision. (HB)
v White willow can increase methotrexate blood levels and toxicity. Avoid combining white willow and methotrexate. (HB)
NSAIDs (Aspirin, Anacin, Bufferin, Celebrex, Arthropan, Voltaren, Voltaren SR & XR, Arthrotec, Advil, Motrin, Relafen, Aleve, Daypro, Vioxx, Ibuprofen, salicylic acid)
v Bilberry may increase the action of NSAIDs; use caution if taking concurrently. (LSR)
v Chondroitin used with NSAIDs or salicylates can cause increased bleeding. Do not use concurrently. (LSR)
v Curcumin may result in an increased risk of bleeding if used with anticoagulants or NSAIDs; avoid concurrent use.(LSR)
v Feverfew Because of the effect feverfew has on prostaglandins it suggests that using feverfew and NSAIDs concurrently might increase the risk of gastropathy and nephropathy. (BG)
v Garlic interacts with aspirin causing increased bleeding by inhibiting platelet aggregation. (RR)v
v Gingko interacts with aspirin causing increased risk of bleeding by inhibiting platelet aggregation factor. (RR)
Oral Contraceptives
v Black cohosh may increase the effects of oral contraceptives; avoid concurrent use. (LSR)
v Chasteberry may interfere with the action of oral contraceptives; avoid concurrent use. (LSR)
v Milk Thistle There is one report that silibinin in Milk Thistle can inhibit bacterial beta-glucoronidase activity. Based on this, alterations in clearance of agents such as oral contraceptives whose durations of action depend upon bacterial beta-glucoronidase in the gut might occur. The herb does not appear to affect CYP enzymes at realistic concentrations. (BG)
v St. John’s wort decreases the effectiveness of oral contraceptives and has caused unwanted pregnancies. (BG)
Sedatives/Hypnotics (Ambien [zolpidem], Dalmane, pentobarbital, Nembutal, Phenobarbital, Seconal, Restoril, Halcion, Compoz, Nytol, Sleep-eze, Sominex, Excedrin P.M., Aspirin Free Anacin P.M.)
v 5-HTP may increase the risk of zolpidem-induced visual hallucinations and therefore these two substances should not be taken together. (HB)
v Black cohosh may increase the hypotensive action of sedatives and hypnotics; avoid concurrent use. (LSR)
v Bupleurum can interact with sedatives enhancing their effects. (SD)
v Hops might potentiate the effects ofsedative drugs according to one animal study. (BG)
v Passionflower mightpotentiate sedative medications. (BG)
v St. John’s wort, which is thought to raise serotonin levels, might cause problems if taken along with zolpidem.(HB)
v Valerian may interact with sedatives prolonging sedation by enhancing the effects of these drugs. (RR)
v Valerian may increase the effects of CNS depressants; avoid concurrent use. (LSR)
Selective Serotonin Reuptake Inhibitors (SSRIs) (paroxetine (Paxil), sertraline (Zoloft), fluoxetine (Prozac), citalopram (Celexa), trazodone, Effexor)
v St. John’s wort interacts with SSRIs causing lethargy, tremors, nervousness, restlessness, agitation, nausea and headache by excessively raising serotonin levels in the brain. (RR)
v St. John’s wort may cause serotonin syndrome* when used with SSRIs and trazodone. Do not use concurrently. (LSR) * (Serotonin syndrome is a toxic reaction requiring immediate medical attention and is associated with too much serotonin. Symptoms may include anxiety, restlessness, confusion, weakness, tremor, muscle twitching or spasm, high fever, profuse sweating and rapid heart beat.)
v Yohimbe may cause increased central nervous stimulation if used with SSRIs; do not use together. (LSR)
Statin drugs (Lipitor, Baycol, Zocor, Mevacor [lovastatin])
v Gotu kola may decrease the effectiveness of antilipidemics; avoid concurrent use. (LSR)
v Grapefruit juice reduces the activity of cytochrome P-450 3A4 enzymes, resulting in increased levels of lovastatin.Presumably, because of this effect, consumption of grapefruit juice along with red yeast rice could increase the risk of side effects. (BG)
v Grapefruit juice impairs the body’s normal breakdown of statins allowing them to build up to potentiallyexcessive levels in the blood. If you are taking statins the safest approach is to avoid grapefruit juice altogether. (HB)
v Red yeast rice contains a mixture of statins. Based on the similarity of red yeast rice to statin drugs, the twoshould not be combined without medical supervision. (HB)
Stimulants (caffeine, Excedrin, pseudoephedrine)
v Ephedra may interact with stimulants causing high blood pressure and rapid or irregular heartbeats by magnifying the stimulating effects of these drugs. (RR)
v Yohimbe may cause increased central nervous stimulation if used with CNS stimulants and caffeine; do not usetogether. (BG & LSR)
Sulfaguanidine
v Ginger interacts with sulfaguanidine to enhance absorption. (SD)
Thyroid Hormone (Armour Thyroid, Euthroid, Synthroid)
v Calcium carbonate supplementation interferes with the body’s absorption of thyroid hormone when taken at the same time. To prevent this interaction take thyroid hormone and calcium supplements as far apart as possible (HB)
v Carnitine may inhibit the effects of thyroid hormone replacement therapy; avoid concurrent use. (LSR)
Tranquilizers (alprazolam, diazepam)
v Kava may interact with alprazolam and diazepam interfering with cognitive motor function by enhancing the effects of these drugs. (RR)
v Valerian may interact with alprazolam and diazepam interfering with cognitive motor function by enhancing the effects of these drugs. (RR)
Tricyclic Anti-Depressants (Elavil)
v Ephedra may cause hypertensive crisis when used with tricyclics; do not use concurrently. (LSR)
v St. John’s wort may cause serotonin syndrome* when used with tricyclics. Do not use concurrently. (LSR) *(Serotonin syndrome is a toxic reaction requiring immediate medical attention and is associated with too much serotonin. Symptoms may include anxiety, restlessness, confusion, weakness, tremor, muscle twitching or spasm, high fever, profuse sweating and rapid heart beat.)
v Yohimbe should not be combined with tricyclic antidepressants. (BG)
v Yohimbe may result in increased hypertension if used with tricyclic antidepressants; dose may need to be lowered (Fugh-Berman, 2000) (LSR)
6. INTERACTIONS BY HERB OR SUPPLEMENT
5-HTP
v 5-HTP when combined with carbidopa might increase the risk of a scleroderma-like syndrome in susceptible individuals. (HB & BG)
v Theoretically because SSRIs have been associated with increased hallucinations in individuals taking zolpidem, combining 5-HTP with zolpidem might present a similar risk. (BG)
Acidophilus and other Probiotics None known. (BG)
Aloe
v Aloe can cause hypokalemia (lowered blood potassium levels) thereby enhancing the effects of cardiac glycosides and anti-arrhythmic agents. (SD)
v Aloe may conceivably interfere with the action of immune suppressant drugs because of the knownimmunomodulatory effects of acemannan (a polysaccharide derived from aloe). (BG)
Alfalfa due to its high vitamin K content could, in theory, reduce the effectiveness of anticoagulants; therefore avoid concurrent use. (HB)
Alpha-Lipoic Acid None known. However, based on pharmacological studies it might increase the effects of insulin, although this effect has not been seen in clinical trials. (BG)
Andrographis None known. (BG)
Angelica (Dong quai)
v Angelica interacts with warfarin to cause bleeding (SD)
v Angelica dahurica may delay elimination of tolbutamide (Ishibara, 2000) Avoid concurrent use. (LSR)
v Dong Quai may interact with warfarin (BG) and it may increase the effects of antiplatelets and oral anticoagulants.(LSR)
Arginine
v Arginine when taken in higher doses along with NSAIDs, aspirin, platelet inhibitors, Fosomax, theophylline products, corticosteroids and alcohol may increase the risk of gastric irritation. (BG)
v Arginine when used in higher doses may increase the risk of gastric irritation when combined with corticosteroidsor alcohol. (BG)
v Arginine when taken IV along with ACE inhibitors or potassium sparing diuretics may lead to fatal hypokalemia(theoretical. (LSR)
Artichoke Leaf None known. (BG) However, artichoke tea may interfere with the absorption of iron salts. (LSR)
Astragalus can interact with cyclosporine, azathioprine and methotrexate to impair intended immunosuppressive effects. (SD)
Basil may increase the hypoglycemic effects of insulin and oral antidiabetics; do not use concurrently. (LSR)
Bay leaf may increase the hypoglycemic effects of insulin and oral antidiabetics; do not use concurrently. (LSR)
Berberine (Barberry) (Berberis aquifolium)
v Berberine may increase the antihypertensive action of antihypertensives; use cautiously. (LSR)
v Berberine may increase the effect of calcium channel blockers. (LSR)
Beta-Carotene None known. (BG)
Beta-Sitosterol None known. (BG)
Betel Palm (Areca catechu) (pan parag)
v Betel Palm increases the effects of alcohol, beta-blockers, cardiac glycosides and MAO inhibitors; do not use concurrently. (LSR)
v Betel Palm when combined with neuroleptics can cause extrapyramidal symptoms; do not use concurrently (FughBerman, 2000). (LSR)
v Betel Palm decreases the action of antiglaucoma agents; do not use concurrently. (LSR)
Bilberry
v Bilberry mildly inhibits platelet aggregation and should not be taken along with anticoagulants or antiplatelet agents. (BG)
v Bilberry may increase hypoglycemia; use caution if taking concurrently with insulin or oral antidiabetics. (LSR)v Bilberry may increase the action of NSAIDs; use caution if taking concurrently. (LSR)
Bitter Melon may increase the effect of oral hypoglycemics. (BG)
Black cohosh
v Black cohosh has weak indications of potential interactions with anti-hypertensive medications. (BG) It may increase the action of antihypertensives; avoid concurrent use. (LSR)
v Black cohosh may alter the effects of other hormone replacement therapies; use together cautiously. (LSR)
v Black cohosh may increase the effects of oral contraceptives; avoid concurrent use. (LSR)
v Black cohosh mayincrease the hypotensive action of sedatives and hypnotics; avoid concurrent use. (LSR)
Black pepper should not be taken along with drugs metabolized by cytochrome P-450. (LSR) (Cytochrome P450 enzymes are found in and on the smooth endoplasmic reticulum of liver and other cells and are responsible for a large number of drug biotransformation reactions.)
Blue cohosh None known. (BG)
Borage should not be used with anticonvulsants because they may lower the seizure threshold. [xxvii]
Boron may raise estrogen levels excessively for women taking HRT. (BG)
Boswellia None known. (BG & LSR)
Brewers yeast None known. (BG)
Bromelain There are theoretical concerns regarding using bromelain along with anticoagulants or antiplatelet agents. Bromelain may increase tissue levels of various antibiotics. An animal study showing that bromelain increase pentobarbital sleeping time suggests the potential for interaction with sedatives. (BG)
Bupleurum can interact with sedatives enhancing their effects. (SD)
Burdock
v Burdock if taken with antidiabetics may increase their hypoglycemic effect; avoid concurrent use. (LSR)
v Burdock may possibly increase the hypotensive effect of antihypertensives; avoid concurrent use. (LSR)
v Burdock may possibly increase the hypotensive effect of calcium channel blockers; avoid concurrent use. (LSR)
Butcher’s Broom
v Butcher’s Broom may increase the action of MAO inhibitors and precipitate a hypertensive crisis so do not use concurrently. (LSR)
v Butcher’s Broom may decrease the action of alpha-adrenergic blockers; avoid concurrent use. (LSR)
Butterbur may enhance the effects of anticholinergics, antimigraine agents and beta-blockers; avoid concurrent use. (LSR)
Calcium
v Calcium supplements when combined with high dose vitamin D may affect the action of calcium channel blockers. (BG)
v Calcium supplements may decrease blood levels of atenolol and possibly other beta-blockers. (BG)
v Calcium may interfere with the absorption of antibiotics in the tetracycline and fluoroquinolones families therefore take calcium supplements at last 2 hours after taking these antibiotics. (BG)
v Calcium supplements may interfere with the absorption of levothyroxine. (BG)
v Calcium carbonate supplementation interferes with the body’s absorption of thyroid hormone when taken at the same time. To prevent this interaction take thyroid hormone and calcium supplements as far apart as possible (HB)
Cardamom None known. (LSR)
Carnitine may inhibit the effects of thyroid hormone replacement therapy; avoid concurrent use. (LSR)
Cat’s claw (Una de gato)
v Evidence suggests that cat’s claw might inhibit CYP3A4. (BG) (CYP is the abbreviation for cytochrome P450 enzymes. The CYP is usually followed by an Arabic numeral, a letter and another Arabic numeral e.g. CYP 2D6. These enzymes are found in and on the smooth endoplasmic reticulum of liver and other cells and are responsible for a large number of drug biotransformation reactions.)
v Cat’s claw may increase the hypotensive effects of antihypertensives; avoid concurrent use. (LSR)
v Cat’s claw may interact with insulin; avoid concurrent use. (LSR)
Cayenne may increase absorption of theophylline, possibly leading to toxic levels. (BG)
Chamomile
v Chamomile contains coumarin compounds that might potentiate anticoagulant or antiplatelet agents, although there are no specific reports of such interactions. (BG)
v Chamomile may increase the effects of other sedatives; avoid concurrent use. (LSR)
v A general survey of plant constituents suggests that chamomile might inhibit CYP3A4. (BG) (CYP is the abbreviation for cytochrome P450 enzymes. The CYP is usually followed by an Arabic numeral, a letter and another Arabic numeral e.g. CYP 2D6. These enzymes are found in and on the smooth endoplasmic reticulum of liver and other cells and are responsible for a large number of drug biotransformation reactions.)
Chasteberry (Chaste tree)
v Chasteberry could conceivably interact with bromocriptine or other drugs intended to affect prolactin levels. For similar reasons, the herb is usually not given along with exogenous estrogen or progesterone or other treatments with endocrine activity. (BG)
v Chasteberry may interfere with the action of oral contraceptives; avoid concurrent use. (LSR)
Chinese cucumber: see Trichosanthes kirilowii
Chondroitin sulfate used with anticoagulants, NSAIDs or salicylates can cause increased bleeding; do not use concurrently. (LSR)
Chromium
v Chromium supplementation may be useful for correcting the reduction of HDL levels that can occur in individuals taking beta-blockers. (BG)
v Chromium may reduce the action of antidiabetics. (LSR)
Cinnamon None known. (LSR)
Citrus bioflavonoids (Diosmin/Hesperidin) None known. (BG)
Coenzyme Q10
v It is possible that individuals taking oral hypoglycemics might need to reduce their dosage, although this has not been reported; and one animal study suggests that CoQ10 can prolong the effects of the antihypertensives enalapril and nitrendipine without increasing their maximum hypotensive effect. (BG)
v Coenzyme Q10 may decrease the action of anticoagulants; avoid concurrent use. (LSR)
Colostrum None known (BG)
Copper Oral contraceptives might increase levels of copper in the body and; conversely, AZT might deplete copper stores. (BG)
Cramp Bark (Black Haw) increases the action of anticoagulants; do not use concurrently. (LSR)
Cranberry Blood levels of antidepressants, antipsychotics and morphine-based analgesics can be reduced by excessive use of cranberry juice; and, theoretically some antibiotics could be inhibited by the reduced urinary pH caused by cranberry. (BG)
Creatine Formal drug interaction studies have not been done. (BG)
Curcumin
v There is a potential for drug interactions because curcumin inhibits cytochrome P-450 isozymes. (BG) (Cytochrome P450 enzymes are found in and on the smooth endoplasmic reticulum of liver and other cells and are responsible for a large number of drug biotransformation reactions.)
v Curcumin may result in an increased risk of bleeding if used with anticoagulants or NSAIDs; avoid concurrent use. (LSR)
v Curcumin may decrease the effectiveness of immunosuppressants; avoid concurrent use. (LSR)
Dandelion
v Since dandelion leaf extract contains coumarins it could theoretically interact with anti-coagulants enhancing their effects. (BG)
v One case report suggests that individuals on lithium should avoid use of herbs with diuretic properties (such as dandelion) due to risk of dehydration and subsequent lithium toxicity. (BG)
v Dandelion may increase the effects of insulin and antihypertensives; avoid concurrent use. (LSR)
DHEA Theoretically DHEA could interact with other hormonal treatments. However, no such interaction has been reported at this time. And theoretically DHEA may reduce some side effects of corticosteroid drugs. (BG)
Dioscorea (Wild yam) None known. (LSR)
Dong quai see Angelica
Echinacea
v Echinacea may cause inflammation of the liver if used with methotrexate. (SDh)
v Evidence suggests that Echinacea angustifolia root might inhibit CYP3A4. (BG) (CYP is the abbreviation for cytochrome P450 enzymes. The CYP is usually followed by an Arabic numeral, a letter and another Arabic numeral e.g. CYP 2D6. These enzymes are found in and on the smooth endoplasmic reticulum of liver and other cells and are responsible for a large number of drug biotransformation reactions.)
v Echinacea may decrease the effects of immunosuppressants and should not be used immediately before, during or after transplant surgery. (LSR)
v Echinacea if taken during pregnancy may promote spontaneous abortions. Therefore Echinacea is contra-indicated for pregnant women. (Chow et al 2006) (Barcz et al 2007)
v Echinacea when combined with acetaminophen may result in increased incidences of hepatotoxicity and nephrotoxicity. [xxviii]
Elderberry Flower None known (BG)
Eleutherococcus (Siberian Ginseng)
v None known. However, based on its purported immunomodulatory actions eleutherococcus (Siberian Ginseng) might interfere with the action of immunosuppressive drugs. (BG)
v Eleutherococcus (Siberian Ginseng) may increase levels of antidiabetic drugs and cardiac glycosides; avoid concurrent use. (LSR)
Ephedra (Ma huang)
v Ephedra may interact with stimulants causing high blood pressure and rapid or irregular heartbeats by magnifying the stimulating effects of these drugs. (RR)
v Ephedra may interact with MAO inhibitors causing extreme high blood pressure by magnifying the stimulating effects of these drugs. (RR)
v Ephedra when combined with MAO inhibitors such as phenelzine (Nardil) may lead to severe tachycardia or hypertension and may be fatal (BG)
v Ephedra may interact with decongestants causing high blood pressure and rapid or irregular heartbeats by magnifying the stimulating effects of these drugs. (RR)
v Ephedra can interact with cardiac glycosides or halothane to produce cardiac arrhythmia. (SD)
v Ephedra may interact with Digoxin causing irregular heartbeats by overriding the drug’s ability to even out irregular heartbeats. (RR)
v Ephedra causes increased hypertension when used with beta-blockers; avoid concurrent use. (LSR)
v Ephedra may cause tachycardia in used with phenothiazines; do not use concurrently. (LSR)
v Ephedra may cause hypertensive crisis when used with tricyclics; do not use concurrently. (LSR)
v Ephedra may cause an increase in blood glucose levels if used along with antidiabetic agents; monitor carefully. (LSR)
Evening Primrose Oil
v Evening Primrose Oil may cause seizures if used with phenothiazines; do not use concurrently. (LSR)
v Evening Primrose Oil should not be used with anticonvulsants because they may lower the seizure threshold. [xxix]
Fennel appears to reduce blood levels of ciprofloxacin, possibly impairing its effectiveness. (HB)
Fenugreek
v Fenugreek may cause reduced absorption of all medications used concurrently. (LSR)
v Fenugreek may cause acute hypoglycemia in diabetic patients who use insulin or other hypoglycemic drugs. (BG)
v Fenugreek may increase the risk of bleeding when used concurrently with anticoagulants. (LSR)
Feverfew
v Because of the effect feverfew has on prostaglandins it suggests that using feverfew and NSAIDs concurrently might increase the risk of gastropathy and nephropathy. (BG)
v Feverfew’s antiplatelet activity suggests a potential interaction with anticoagulant and antiplatelet drugs as well as supplements such as garlic, ginkgo, policosanol and high-dose vitamin E. (BG)
Figwort: see Scrophularia nodosa
Fish Oil Although fish oil does not appear to increase the bleeding complications caused by aspirin, interactions with anticoagulants such as warfarin have not been ruled out. (BG)
Flax may cause a decrease in the absorption of all oral medications if taken concurrently. (LSR)
Flaxseed As with other high-fiber foods, flaxseed supplementation could potentially require a reduction in hypoglycemic drug dosage. (BG)
Flaxseed oil None known. (BG)
Folate (Folic Acid)
v Folate (Folic Acid) may increase seizures in individuals with epilepsy and may interfere with phenytoin therapy. (BG)
v Folate (Folic Acid) may safely reduce some of the side effects of methotrexate (particularly elevated liver enzymes) when taken at the same time. (BG)
Fo-ti None known. (LSR)
Gamma-Linolenic Acid (GLA) None known. (BG)
Ganoderma lucidum (Reishi) None known. (BG)
Garlic
v Garlic interacts with aspirin and warfarin causing increased bleeding by inhibiting platelet aggregation. (RR)v Garlic interacts with warfarin to cause bleeding. (SD)
v Garlic has a blood thinning effect and therefore may be dangerous to take along with heparin. (HB)
v Garlic appears to possess anti-thrombotic activity and should be used with caution in patients on anticoagulants. (BG)
v It is conceivable that garlic could interact with ginkgo, policosanol and high-dose vitamin E, which also have anti-coagulant effects. (BG)
v Garlic has hypoglycemic effects; therefore the dosages of insulin or oral antidiabetics may need to be adjusted if taken concurrently. (LSR)
Genistein None known. (BG)
Gentiana may interfere with absorption of iron salts; separate by at least 2 hours. (LSR)
Ginger
v Ginger interacts with sulfaguanidine to enhance absorption. (SD)
v Because of its effects on platelet action, ginger should be used with care in patients using anticoagulants or antiplatelet agents. (BG)
v Ginger may increase absorption of all medications taken orally. (LSR)
Gingko
v Gingko interacts with aspirin and warfarin causing increased risk of bleeding by inhibiting platelet aggregation factor. (RR)
v Gingko has a blood thinning effect and therefore may be dangerous to take along with heparin (HB) and anticoagulants and antiplatelet agents. (LSR)
v Ginkgo is known to inhibit platelet activation factor and for this reason it is advisable to use caution when combining ginkgo with warfarin, heparin, aspirin or any other drugs with anticoagulant or antiplatelet effects. One case report suggests a probable interaction between ginkgo and aspirin. (BG)
v Ginkgo may increase the action of MAOIs if taken concurrently (theoretical). (LSR)
v Ginkgo may decrease the anticonvulsant effect of anticonvulsants; avoid concurrent use. (LSR)
v Ginkgo may interact with acetaminophen to increase the risk of bleeding. [xxx]
v It is conceivable that ginkgo could interact with garlic, phosphatidylserine, policosanol and vitamin E. (BG)
Ginseng
v Ginseng may decrease the action of anticoagulants. (LSR)
v Ginseng (Panax) interacts with warfarin to cause bleeding or to decrease effectiveness. (SD)
v Ginseng may provide an additive anticonvulsant action (theoretical). (LSR)
v Ginseng may diminish the effect of immunosuppressants; do not use immediately before, during or after transplant surgery. (LSR)
v Ginseng use along with MAOIs may result in manic-like syndrome. (LSR)
v Ginseng may interact with phenelzine sulfate to cause manic episodes and headaches. (SD)
v Ginseng (Asian) causes headache, insomnia, trembling and other symptoms when taken along with phenelzine, so it is best to avoid taking these two substances together until more is known. (HB)
v Ginseng is known to decrease blood glucose levels and therefore it may increase the hypoglycemic effect of antidiabetics; avoid concurrent use. (LSR)
v Ginseng (American and Asian) interacts with hypoglycemic agents for diabetes causing hypoglycemia and shock because the ginsenosides in ginseng lower blood sugar. (RR)
v Ginseng (according to one case report) may inhibit CYP3A4. (BG) (CYP is the abbreviation for cytochrome P450 enzymes. The CYP is usually followed by an Arabic numeral, a letter and another Arabic numeral e.g. CYP 2D6. These enzymes are found in and on the smooth endoplasmic reticulum of liver and other cells and are responsible for a large number of drug biotransformation reactions.)
Glucosamine
v The results of one trial suggest that patients on diuretics might need to take higher doses of glucosamine for full effect. (BG)
v Glucosamine may increase the effects of antidiabetics (theoretical). LSR)
Glutamine Theoretically, high doses of glutamine may overwhelm anticonvulsant drugs and pose a risk to individuals with seizure disorders because many of them work by blocking glutamine stimulation in the brain. (BG)
Goldenseal
v Goldenseal might inhibit CYP3A4 thereby causing a decrease of cyclosporine leading to transplant rejection. If you take cyclosporine the safest approach is to avoid grapefruit juice altogether. (BG) (CYP is the abbreviation for cytochrome P450 enzymes. The CYP is usually followed by an Arabic numeral, a letter and another Arabic numeral e.g. CYP 2D6. These enzymes are found in and on the smooth endoplasmic reticulum of liver and other cells and are responsible for a large number of drug biotransformation reactions.)
v Goldenseal may worsen high blood pressure. (SDh)
v Goldenseal may increase the effects of anti-arrhythmic drugs, alcohol, antihypertensives, beta-blockers and central nervous system depressants; do not use concurrently. (LSR)
v Goldenseal may decrease the effects of anticoagulants, and the absorption of vitamin B; do not use concurrently. (LSR)
v Goldenseal may slow the metabolism of azole antifungals, benzodiazepines, calcium channel blockers and statins; avoid concurrent use. (LSR)
Gotu kola may decrease the effectiveness of antidiabetics and antilipidemics; avoid concurrent use. (LSR)
Grapefruit juice
v Grapefruit juice slows the body’s normal breakdown of cyclosporine, allowing it to build up to potentially excessive levels in the blood. If you take cyclosporine the safest approach is to avoid grapefruit juice altogether. (HB)
v Grapefruit juice causes decreased absorption of itraconazole, which might result in treatment failure. It is thus best to avoid taking grapefruit juice along with itraconazole. (HB)
v Grapefruit juice impairs the body’s normal breakdown of statins allowing them to build up to potentially excessive levels in the blood. If you are taking statins the safest approach is to avoid grapefruit juice altogether. (HB)
v Grapefruit juice reduces the activity of cytochrome P-450 3A4 enzymes, resulting in increased levels of lovastatin. Presumably, because of this effect, consumption of grapefruit juice along with red yeast rice could increase the risk of side effects. (BG) (Cytochrome P450 enzymes are found in and on the smooth endoplasmic reticulum of liver and other cells and are responsible for a large number of drug biotransformation reactions.)
v Grapefruit juice slows the body’s normal breakdown of benzodiazepines, allowing them to build up to potentially dangerous levels in the blood. Therefore avoid grapefruit juice altogether if taking benzodiazepines. (LSR)
v Grapefruit juice impairs the breakdown of calcium channel blockers allowing them to build up to potentially dangerous levels in the blood. Avoid grapefruit juice altogether if taking calcium channel blockers. (HB)
Grape Seed Extract see OPCs
Green tea
v Green tea contains vitamin K, and large doses could potentially interfere with the effectiveness of anticoagulants. In addition, the caffeine in green tea could cause significant interactions with MAO inhibitors. (BG)
v Green tea may increase the action of some bronchodilators. (LSR)
Guggul None known. (BG & LSR)
Gymnema may possibly increase the action of insulin, other hypoglycemic or oral antidiabetic drugs, leading to hypoglycemic reactions (theoretical). (BG & LSR)
Hawthorn
v Hawthorn may interact with or potentiate other cardiovascular drugs and such combinations should be used with caution. (BG)
v Hawthorn may increase hypotension when used with antihypertensives; avoid concurrent use. (LSR)
v Hawthorn may increase the effects of cardiac glycosides; monitor concurrent use carefully. (LSR)
v Hawthorn may increase the sedative effects of CNS depressants such as alcohol, barbiturates and psychotropics; avoid concurrent use. (LSR)
Hops
v Hops might potentiate the effects of sedative drugs according to one animal study. (BG)
v Hops It is theoretically possible that the phytoestrogenic action of hops could have an impact on hormonal therapies such as estrogen. (BG & LSR)
v Hops may cause increased CNS effects when taken concurrently with antidepressants, antipsychotics, antihistamines, alcohol and CNS depressants. (LSR)
v Hops may decrease the levels of cytochrome P-450 drugs such as carbamazepine, warfarin and theophylline. (LSR) (Cytochrome P450 enzymes are found in and on the smooth endoplasmic reticulum of liver and other cells and are responsible for a large number of drug biotransformation reactions.)
Horse Chestnut
v Horse chestnut could theoretically interfere with anticoagulants, aspirin and other salicylates because of the coumarins in it. (BG & LSR)
v Horse chestnut may increase the hypoglycemic effects of diabetic medications. (LSR)
Huperzine A None known. (BG)
Inositol (Vitamin B8) None known. (BG)
Ipriflavone
v Ipriflavone may interact with numerous CYP enzymes, including CYP3A, CYP1A2 and CYP2C9. These interactions may lead to increased serum levels of theophylline, caffeine, theobromine, other polycyclic aromatic compounds, tolbutamide, phenytoin and warfarin. (BG) (CYP is the abbreviation for cytochrome P450 enzymes. The CYP is usually followed by an Arabic numeral, a letter and another Arabic numeral e.g. CYP 2D6. These enzymes are found in and on the smooth endoplasmic reticulum of liver and other cells and are responsible for a large number of drug biotransformation reactions.)v Based on the observed lymphopenic effects of ipriflavone in which it causes decreased serum lymphocyte levels, it should be used with caution in individuals taking immunosuppressant drugs. (BG)
Iron
v Iron may interfere with the absorption of both levodopa and carbidopa by binding to them. You should separate the times you take iron and these drugs by as long as possible. (HB)
v Iron supplements can interfere with the absorption of captopril and perhaps other ACE inhibitors. To minimize any potential problems take iron supplements and ACE inhibitors 2 to 3 hours apart. (HB)
v Iron supplements may mutually interfere with the absorption of antibiotics in the tetracycline and quinolone families, levodopa, methyldopa, carbidopa, penicillamine, thyroid hormone, captopril and possible other ACE inhibitors. Separating intake of the iron and drugs by at least 2 hours is likely to forestall any absorption problem. (BG)
Kava
v Kava may interact with alprazolam and diazepam interfering with cognitive motor function by enhancing the effects of these drugs. (RR)
v Case reports suggest that kava might increase the risk of dystonic reactions in individuals on phenothiazines and could additionally counteract the effectiveness of L-dopa. (BG)
v Kava may result in neuroleptic movement disorders if taken along with antipsychotics. (LSR)
v Kava taken with barbiturates may result in increased sedation. (LSR)
v Kava taken with benzodiazepines may result in increased sedation and coma; do not use concurrently (theoretical). (LSR)v High doses of alcohol increased the effects and toxicity of kava in mice. (BG)
v Kava when combined with acetaminophen may result in increased incidences of hepatotoxicity and nephrotoxicity. [xxxi]
Lecithin None known. (LSR)
Lemon Balm may increase the sedative effects of barbiturates and CNS depressants. (LSR)
Lentinan (Shiitake mushroom) None known. (LSR)
Licorice
v Licorice taken in high dosages or used long-term causes low blood levels of potassium. Loop diuretics also cause potassium loss. Therefore one should avoid taking licorice with loop diuretics. DGL licorice should not affect potassium levels and so should not pose a danger for loop diuretic users. (HB)
v Licorice should never be taken along with potassium sparing diuretics. Potassium-sparing diuretics such as Amiloride and Aldactone cause the body to retain potassium whereas licorice has the opposite effect causing the body to lose potassium and thus directly counteracts the effect of these drugs. (HB)
v Licorice can interact with thiazide diuretics enhancing their effects. (SD)
v Licorice may cause increased hypokalemia if used with diuretics; avoid concurrent use. (LSR)
v Licorice can interact with diuretics negating the blood-pressure lowering effect of these drugs and causing irregular heartbeats from increased potassium loss. Licorice mimics the effect of aldosterone, an adrenal hormone that causes sodium retention and potassium loss. (RR)
v Licorice can interact with corticosteroids to enhance their effects; avoid concurrent use. (SD & LSR)
v Licorice can interact with corticosteroids causing salt and water retention, lowered blood potassium, elevated blood pressure, elevated blood sugar and excessive immune suppression by inhibiting an enzyme that breaks down corticosteroids, thus increasing blood levels of the drug. (RR)
v Licorice can interact with digitalis or other cardiac glycosides causing increased sensitivity (SD) increased toxicity and increased hypokalemia; do not use concurrently. (LSR)
v Licorice increases the cardiac effects of anti-arrhythmic drugs and therefore do not use concurrently. (LSR)
v Licorice may cause increased hypokalemia if used with antihypertensives; do not use concurrently. (LSR)
v Licorice. Whole licorice can cause sodium retention and increase blood pressure, thus counteracting the intended effects of ACE inhibitors. DGL (deglycyrrhizinated licorice) is an altered form of the herb that should not cause these problems. (HB)
Lutein None known. (BG)
Lycopene None known. (BG & LSR)
Lysine used in large amounts causes increased aminoglycoside toxicity; avoid concurrent use. (LSR)
Magnesium
v Magnesium can mutually interfere with absorption of antibiotics in the tetracycline and fluoroquinolones families, as well as nitrofurantoin, penicillamine, ACE inhibitors, phenytoin and H2 blockers. To avoid this problem, magnesium should be taken at least 2 hours before or after taking these drugs. (BG)
v Magnesium might increase the effectiveness of oral hypoglycemics in the sulfonylurea family, potentially creating a risk of hypoglycemia. (BG)
v Use caution supplementing with magnesium if taking amiloride, because amiloride may reduce urinary magnesium excretion. (BG)
Ma huang: see Ephedra
Maitake mushroom may decrease the effects of immunosuppressants; do not use immediately before, during or after transplant surgery. (LSR)
Marshmallow may reduce the absorption of oral medications; do not use concurrently. (LSR)
Melatonin
v Melatonin may increase the anxiolytic effects of benzodiazepines; use together cautiously. (LSR)
v Melatonin used with cerebral stimulants may have a synergistic effect and exacerbate insomnia; avoid concurrent use. (LSR)
v Melatonin used with DHEA may decrease cytokine production; avoid concurrent use. (LSR)
v Melatonin used with magnesium or zinc increases inhibition of N-methyl-D-aspartate (NMDA) receptors; avoid concurrent use. (LSR)
v Melatonin increases the blocking properties of succinylcholine; avoid concurrent use. (LSR)
MSM None known. (BG)
Milk thistle (silibinin)
v There is one report that silibinin can inhibit bacterial beta-glucoronidase activity. Based on this, alterations in clearance of agents such as oral contraceptives whose durations of action depend upon bacterial beta-glucoronidase in the gut might occur. The herb does not appear to affect CYP enzymes at realistic concentrations. (BG)
v Milk thistle Test-tube studies suggested that milk thistle may inhibit certain enzymes (cytochrome P450) in the liver that break down some drugs and supplements, which could lead to higher blood levels of these substances and increased side effects. However, this hasn’t happened in more recent clinical studies. [xxxii]
Minor Bupleurum Decoction has been reported to increase the risk of acute pneumonitis associated with use of interferon. [xxxiii]
Myrrh may cause increased hypoglycemic effects when used with antidiabetic agents; avoid concurrent use. (LSR)
N-Acetyl Cysteine (NAC) Although NAC may enhance or maintain the effectiveness of nitrate therapy, it can also increase headaches. (BG)
Neem None known. (BG & LSR)
Nettle
v Nettle (based on animal studies) may interact with hypoglycemic, antihypertensive or sedative medications; however, there are no case reports of interactions. (BG)
v Nettle may lead to increased CNS depression if used with CNS depressants such as alcohol, barbiturates, sedative/hypnotics and antipsychotics. (LSR)
v Nettle when combined with lithium may result in dehydration, lithium toxicity. (LSR)
v Nettle may decrease the effect of anticoagulants; avoid concurrent use. (LSR)
v Nettle may interfere with the absorption of iron salts. (LSR)
OPCs (Grape Seed Extract) might (based on the activity of other flavonoids) potentiate anticoagulant and antiplatelet agents. (BG)
Oxerutins theoretically might potentiate anticoagulants. (BG)
Papain might potentiate anticoagulant and antiplatelet agents. (BG)
Passionflower
v Passionflower might potentiate sedative medications. (BG)
v Passionflower may cause increased sedation when used with CNS depressants; avoid concurrent use (theoretical). (LSR)
v Passionflower may cause increased MAOI activity when used with MAOIs; avoid concurrent use (theoretical). (LSR)
Pau d’Arco
v Pau d’Arco theoretically may interfere with conventional chemotherapeutic agents. (BG)
v Pau d’Arco may result in an increased risk of bleeding if used with anticoagulants; avoid concurrent use (theoretical). (LSR)
PC SPES might be expected to present all the same risks of drug interactions as estrogen, warfarin and indomethacin. (BG)
Pectin decreases absorption of all drugs, vitamins and minerals if taken concurrently. (LSR)
Peppermint None known. (BG)
Perilla may augment the effect of corticosteroids; avoid concurrent use. (LSR)
Phenylalanine (D or DL) might increase the risk of developing tardive dyskinesia when combined with antipsychotic drugs. (BG)
Phosphatidylcholine None known. (BG)
Phosphatidylserine In vitro studies report that fatty acid esters of phosphatidylserine and phosphatidylethanolamine can synergistically stimulate the anticoagulant effect of heparin. (BG)
Policosanol
v Policosanol appears to potentiate the antiplatelet effects of aspirin. For this reason, caution should be exercised when combining policosanol with any antiplatelet or anticoagulant agent. It is also possible that it could potentiate the anticoagulant properties of garlic, ginkgo, and high-dose vitamin E. (BG)
v According to one report, policosanol might potentiate the action of levodopa, causing increased dyskinesias. (BG)
Pomegranate None known. (LSR)
Potassium
v Potassium supplements taken along with potassium-sparing diuretics could raise your potassium levels too high resulting in nausea, vomiting, irritability, diarrhea and changes in heart function. (HB)
v Potassium may interact with ACE inhibitors by causing irregular heart rhythm, muscle weakness, nausea, vomiting, irritability and diarrhea by increasing potassium levels in the blood even higher. (ACE inhibitors cause the body to retain more potassium than usual.) (HB)
v Potassium citrate may lead to decreased blood levels and therapeutic effects of methotrexate. Avoid use altogether except under medical supervision. (HB)
Propolis None known. (LSR)
Progesterone cream A potential exists for CYP enzyme system interactions. (BG) (CYP is the abbreviation for cytochrome P450 enzymes. The CYP is usually followed by an Arabic numeral, a letter and another Arabic numeral e.g. CYP 2D6. These enzymes are found in and on the smooth endoplasmic reticulum of liver and other cells and are responsible for a large number of drug biotransformation reactions.)
Pycnogenol None known. (LSR)
Pygeum None known (BG & LSR)
Quercetin None known, however, because of quercetin’s effects on platelet aggregation, interactions with antiplatelet and anticoagulant drugs could occur. (BG)
Red yeast rice
v Red yeast rice interacts with cyclosporine increasing the risk of CK elevation and rhabdomyolysis. (Prasad et al 2002) (FA)
v Red yeast rice has drug interactions which are presumably similar to those of other statin drugs, therefore it is reasonable to assume that the incidence of myopathy or rhabdomyolysis may increase in patients also receiving cyclosporine, erythromycin, azole antifungals, high doses of niacin and fibric acid derivatives. In addition using warfarin at the same time may increase the risk of bleeding. (BG)
v Grapefruit juice reduces the activity of cytochrome P-450 3A4 enzymes, resulting in increased levels of lovastatin. Presumably, because of this effect, consumption of grapefruit juice along with red yeast rice could increase the risk of side effects. (BG) (Cytochrome P450 enzymes are found in and on the smooth endoplasmic reticulum of liver and other cells and are responsible for a large number of drug biotransformation reactions.)
v Combining red yeast rice with standard statin drugs would not make sense. (BG)
v Red yeast rice contains a mixture of statins. Based on the similarity of red yeast rice to statin drugs, the two should not be combined without medical supervision. (HB)
Rhubarb (Chinese rhubarb)
v Rhubarb (Chinese rhubarb) used chronically can cause hypokalemia (lowered blood potassium levels) and enhance the effects of thiazide diuretics and corticosteroids. (LSR)
v Chinese rhubarb used chronically can cause hypokalemia and enhance the effects of cardiac glycosides (SD) and anti-arrhythmic drugs. (SD & LSR)
Rose hips None known. (LSR)
Salvia interacts with warfarin to cause bleeding. (SD)
SAMe
v SAMe can increase the metabolism of certain drugs by facilitating their conjugation. However, the clinical significance of this observation is unknown. (BG)
v SAMe may lead to serotonin syndrome* if combined with antidepressants; do not use concurrently. (LSR) * (Serotonin syndrome is a toxic reaction requiring immediate medical attention and is associated with too much serotonin. Symptoms may include anxiety, restlessness, confusion, weakness, tremor, muscle twitching or spasm, high fever, profuse sweating and rapid heart beat.)
Saw Palmetto
v Saw Palmetto may increase the anticoagulant effects of anticoagulants, antiplatelets and NSAIDs leading to increased bleeding time; avoid concurrent use. (LSR)
v Saw Palmetto may antagonize hormone therapy; avoid concurrent use (theoretical). (LSR)
v Saw Palmetto may increase or decrease the effect of immunostimulants; avoid concurrent use (theoretical). (LSR)
Schisandra may decrease the effectiveness of immunosuppressants; avoid use before, during or after transplant surgery. (LSR)
Scrophularia nodosa (Figwort)
v Scrophularia nodosa may increase the effects of antiarrhythmics and beta-blockers; do not use concurrently. (LSR)
v The action of figwort may be increased by cardiac glycosides; do not use concurrently. (LSR)
v Scrophularia nodosa is contraindicated in ventricular tachycardia due to its content of cardiac glycosides. (Brinker p. 96)
Scutellaria baicalensis
v Scutellaria baicalensis may increase sedation of CNS depressants; avoid concurrent use. (LSR)
v Scutellaria baicalensis may decrease the effects of immunosuppressants; avoid concurrent use. (LSR)
Selenium deficiency may result from treatment with corticosteroids, proton pump inhibitors and H2 blockers. (BG)
Siberian Ginseng: see Eleutherococcus
Silibinin see Milk thistle
Slippery elm may decrease the absorption of iron salts; separate by 2 hours. (LSR)
Soy isoflavones may impair thyroid function or reduce absorption of thyroid medication. (BG & LSR)
St. John’s wort
v St. John’s wort interacts with SSRIs causing lethargy, tremors, nervousness, restlessness, agitation, nausea and headache by excessively raising serotonin levels in the brain. (RR)
v St. John’s wort, which is thought to raise serotonin levels, might cause problems if taken along with zolpidem. (HB)
v St. John’s wort can interact with cyclosporine causing transplant rejection (Ernst 2002) so absolutely avoid taking St. John’s wort with cyclosporine. (RR & BG)
v St. John’s wort intake increases the expression of intestinal P-glycoprotein and the expression of CYP3A4 in the liver and intestine. The combined up-regulation in intestinal P-glycoprotein and hepatic and intestinal CYP3A4 impairs the absorption and stimulates the metabolism of cyclosporine, leading to subtherapeutic plasma levels. [xxxiv] (CYP is the abbreviation for cytochrome P450 enzymes. The CYP is usually followed by an Arabic numeral, a letter and another Arabic numeral e.g. CYP 2D6. These enzymes are found in and on the smooth endoplasmic reticulum of liver and other cells and are responsible for a large number of drug biotransformation reactions.)
v St. John’s wort has clinically relevant activity by its effect on multiple cytochromes as well as the transport protein p-glycoprotein. (BG)v St. John’s wort may interact with estrogen causing breakthrough bleeding. (RR)
v St. John’s wort interacts with digoxin-based drugs and can theoretically lead to a worsening of heart failure and irregular heartbeats. (RR)
v St. John’s wort may interact with Indinavir causing decreased drug effectiveness and worsening of HIV infection by lowering blood levels of the drug. (SD)
v St. John’s wort interacts with amitriptyline (and theoretically other tricyclic anti-depressants) causing a worsening of depression. (RR)
v St. John’s wort interacts with phenylpiperazine antidepressants such as nefazodone and trazodone causing lethargy, tremors, nervousness, restlessness, agitation, nausea and headache by excessively raising serotonin levels in the brain. (RR)
v St. John’s wort may interact with warfarin causing increased risk of blood clots by lowering blood levels of warfarin. (RR)
v St. John’s wort lowers blood levels of theophylline causing a worsening of asthma symptoms. Therefore you should not combine St. John’s wort and theophylline. (RR & HB)
v St. John’s wort can reduce serum concentrations of protease inhibitors, nonnucleoside reverse transcriptase inhibitors such as nevirapine, cyclosporine, digoxin, warfarin, tricyclic antidepressants, simvastatin and theophylline. (BG)
v St. John’s wort decreases the effectiveness of oral contraceptives and has caused unwanted pregnancies. (BG)
v St. John’s wort is suspected to interact with etoposide, teniposide, mitoxantrone, doxorubicin, clozapine and olanzapine. (BG)
v St. John’s wort may potentiate the effects of photosensitizing agents. (BG)
v St. John’s wort may lead to severe photosensitivity when combined with ACE inhibitors, loop diuretics, thiazide diuretics, NSAIDs oral contraceptives, sulfonamides, sulfonylureas and tetracyclines; avoid concurrent use. (LSR)
v St. John’s wort may cause serotonin syndrome* when used with antidepressants, tricyclics, amphetamines, SSRIs and trazodone. Do not use concurrently. (LSR) * (Serotonin syndrome is a toxic reaction requiring immediate medical attention and is associated with too much serotonin. Symptoms may include anxiety, restlessness, confusion, weakness, tremor, muscle twitching or spasm, high fever, profuse sweating and rapid heart beat.)
v St. John’s wort may increase MAO inhibition; do not use alcohol and St. John’s wort or MAOIs and St. John’s wort. (LSR)
Tea Tree Oil None known. (BG)
Trichosanthes kirilowii (Chinese cucumber) None known. (LSR)
Tylophora indica None known. (BG)
Tyrosine None known. (BG)
Una de gato: see Cat’s claw
Valerian
v Valerian may interact with alprazolam and diazepam interfering with cognitive motor function by enhancing the effects of these drugs. (RR)
v Valerian may interact with sedatives prolonging sedation by enhancing the effects of these drugs. (RR)
v Valerian may enhance the effects of alcohol. (RR)
v Valerian may, according to animal studies, potentiate pentobarbital, hexobarbital and thiopental. (BG)
v Valerian may increase the effects of CNS depressants; avoid concurrent use. (LSR)
Vinpocetine may impair the effectiveness of warfarin. (BG)
Vitamin A might interact with Accutane by increasing each other’s toxicity due to their structural similarities. (HB)
v Vitamin A may increase the anticoagulant effects of warfarin. (BG)
v Pregnant women taking valproic acid may be at increased risk of adverse effects from vitamin A. (BG)
v Vitamin A taken along with isotretinoin might increase vitamin A toxicity. (BG)
Vitamin B3 (Niacin) might increase serum levels of anticonvulsant medications including carbamazepine and primidone, possibly requiring reduction in drug dosage. (BG)
Vitamin B6 (Pyridoxine) in higher doses can reduce the therapeutic effects of levodopa. Fortunately, however, since most people with Parkinson’s disease use a combination of levodopa and carbidopa rather than levodopa alone, carbidopa neutralizes the effect of vitamin B6 on levodopa making the interaction with B6 unlikely in practice. (HB & BG)
Vitamin C
v Vitamin C might reduce the effects of warfarin and heparin according to weak evidence. (BG)v Vitamin C, according to one study, at very high doses (3 g daily) might increase serum levels of acetaminophen. (BG)
Vitamin D
v Vitamin D when combined with calcium supplements might interfere with calcium channel blockers. (BG)
v Vitamin D when combined with calcium and thiazide diuretics can lead to hypercalcemia. (BG)
Vitamin E
v Vitamin E might potentiate anticoagulant or antiplatelet medications based on its anticoagulant properties. (BG)
v Vitamin E could theoretically interact with herbs and supplements that possess anticoagulant or antiplatelet effects such as garlic, policosanol and ginkgo. (BG)
v Vitamin E might enhance insulin sensitivity in individuals with type 2 diabetes. This could lead to a risk of hypoglycemia and may warrant adjustment of oral hypoglycemic medications. (BG)
Vitamin K antagonizes the action of warfarin. (BG)
White willow
v White willow, also known as willow bark, contains a substance that is converted by the body into a salicylate similar to aspirin. Since combining aspirin with heparin increases the risk of abnormal bleeding, it would be advisable not to combine white willow with heparin. (HB)
v White willow may adversely interact with alcohol, anticoagulants, antiplatelet agents, anti-inflammatory agents, sulfonamide drugs, methotrexate, metoclopramide, phenytoin, probenecid, spironolactone and other potassium-sparing diuretics and valproate. (BG)
v White willow can increase methotrexate blood levels and toxicity. Avoid combining white willow and methotrexate. (HB)
Yohimbe
v Yohimbe should not be combined with tricyclic antidepressants, phenothiazines, antihypertensive agents or central nervous system stimulants. (BG)
v Yohimbe may result in increased toxicity if used with alpha-adrenergic blockers; avoid concurrent use. (LSR)
v Yohimbe may cause increased central nervous stimulation if used with SSRIs, CNS stimulants and caffeine; do not use together. (LSR)
v Yohimbe may result in increased hypertension if used with tricyclic antidepressants; dose may need to be lowered (Fugh-Berman, 2000) (LSR)
v Yohimbe may result in increased toxicity if used with phenothiazines; avoid concurrent use. (LSR)
Zinc supplements can interfere with the absorption of tetracyclines, fluoroquinolones and penicillamine. (BG).
7. TOWARDS A BETTER UNDERSTANDING OF HERBS AND DRUGS
Where to find out more about Herb-Drug InteractionsThere are many herbs for which no drug interactions have been documented; and as new drugs are made available there is always the potential for interactions of herbs with these new drugs. Besides contacting your medical doctor or health care provider who has extensive knowledge of herb-drug interactions there are some good web sites where you can go to for accurate and fairly up to date information on herb-drug interactions, herbal safety and efficacy.
For information on herbal safety and quality Steven Foster, the lead editorial adviser of Herbs for Health, recommends several websites including the American Botanical Council website at www.herbalgram.org and the American Herbal Products Association website at www.ahpa.org. [xxxv]
For information and studies on Chinese herbal safety we recommend consulting the website of the Institute of Traditional Medicine at www.itmonline.org/safety.htm. Subhuti Dharmananda has published an excellent article on this website entitled “Checking for Possible Herbs-Drugs Interactions” which we recommend highly.
For information on the latest published reviews and studies on herb-drug interactions we recommend consulting the vast database of Medline athttp://www.ncbi.nlm.nih.gov/PubMed/.
What The Future Looks Like The WHO has published guidelines in order to define basic criteria for evaluating the quality, safety and efficacy of herbal medicines. The WHO has also prepared pharmacopeic monographs on herbal medicines and the basis of guidelines for the assessment of herbal drugs. [xxxvi]
The United States Pharmacopeia plans to fill the information gap by preparing monographs on many popular botanicals that should be useful to both consumers and health professionals. [xxxvii]
8. CHEMICAL COMPONENTS OF HERBS
A. Alkaloids
Examples of herbs that contain alkaloids are coptis, phellodendron, corydalis, Sophora (root), areca seed, Uncaria and lotus seed.
Alkaloids inhibit bacteria, they have sedative actions (except in the cases of ephedrine in ma-huang and caffeine in tea which are stimulants) and they are antispasmodic.
B. Glycosides
1. Flavonoid glycosides
Herbs with flavonoid constituents include eclipta, licorice, pueraria, sanguisorba and scute. Flavonoids act by reducing inflammation, promoting circulation and stopping bleeding.
2. Anthraquinone glycosides
Quinones are found in the salvia, rhubarb, hu-chang and peony. They act to promote microcirculation and reduce inflammation.
3. Saponin glycosidesv
Saponin glycosides are found in ginseng, licorice, dioscorea, jujube, platycodon and bupleurum. They act by tonifying deficiencies, regulating blood sugar and favorably influencing adrenal hormones.
4. Cardioactive glycosides
5. Coumarin glycosidesv
Coumarins are found in angelica, chiang-huo, tu-huo, cnidium fruit and psoralea.
Coumarins relive pain, reduce inflammation and dispel chills.
6. Other Glycosides.
Cyanogenic glycosidesb.
Phenol glycosidesc.
Thioglycoside glycosidesd.
Alkaloid glycosides
C. Essential Oils
D. Organic Acids
E. Tannins
F. Amino Acids
G. Protein and Enzymes
H. Sugars
Sugars include the class of compounds known as polysaccharides, which are found in ganoderma, cordyceps, coriolus, astragalus and lycium. Polysaccharides enhance bone marrow function, promote macrophage activity and have anti-ulcer effects
I. Wax and Lipids
J. Resins
K. Inorganic Components These include such minerals as potassium, calcium, magnesium and iodine.
L. Pigments Aromatic terpenes are found in citrus, menthe, schizonepeta, perilla leaf, cardamom and cyperus. They act by relieving pain, relieving inflammation, and calming digestive system spasms.
a. Chlorophylls
b. Carotenoids
c. Flavinoids
d. Betalains [xxxviii] [xxxix]
Formulas that invigorate the yang may produce an agitation response in those who suffer from a kidney or liver yin deficiency.
Formulas that tonify the qi and blood may cause tiredness, flatulence, bloating or other negative symptoms in persons who suffer from qi stagnation.
Some very bitter herbs, such as gentiana and coptis, are known to cause nausea and loss of appetite soon after ingestion.
Persons with hypoacidity of the stomach may experience further reduction in stomach acid when consuming calcium-containing materials such as oyster shell.[xl]
Abebe, W, “Herbal medication: a potential for adverse interactions with analgesic drugs” J Clin Pharm Ther 2002 Dec;27(6):391-401
Awang DV & A Fugh-Berman, “Herbal interactions with cardiovascular drugs” J Cardiovasc Nurs 2002 Jul;16(4):64-70
Barnes, J, “Pharmacovigilance of herbal medicines: a UK perspective.” Drug Saf. 2003;26(12):829-51
Barnes, P.M. & Eve Powell-Griner, “Complementary and Alternative Medicine Use Among Adults: United States, 2002” CDC Advance Data Report /#343, May 27, 2004www.nccam.nih.gov/news/camsurvey.htm
Bensky, Dan & Randall Barolet, Chinese Herbal Medicine Formulas & Strategies, Seattle: Eastland Press, 1990
Bensky, Dan & Andrew Gamble, Chinese Herbal Medicine: Materia Medica, Seattle: Eastland Press, 1986
Boix, John, Cancer & Natural Medicine, Princeton, MN: Oregon Medical Press 1996
Bratman, Steven, MD & Andrea M. Girman, MD MPH, Mosby’s Handbook of Herbs and Supplements and their Therapeutic Uses, St Louis: Mosby, 2003
Brazier NC & MA Levine, “Drug-herb interaction among commonly used conventional medicines: a compendium for health care professionals” Am J Ther 2003 May-Jun;10(3):163-9
Brinker, Francis, N.D. Herb Contraindications & Drug Interactions, Sandy, OR: Eclectic Medical Publications, 2001
Calixto, J.B. “Efficacy, safety, quality control, marketing and regulatory guidelines for herbal medicines (phytotherapeutic agents), Brazilian Journal of Medical and Biological Research, (2000) 33:179-189
Caron, M.F. & C.M. White, “Evaluation of the antihyperlipidemic properties of dietary supplements” Pharmacotherapy 2001 Apr;21(4):281-7
Coon, JT & E Ernst, “Panax ginseng: a systematic review of adverse effects and drug interactions” Drug Saf 2002;25(5):323-44
Cupp, MJ, “Herbal remedies: adverse effects and drug interactions” Am Fam Physician 1999 Mar 1;59(5):1239-45
Dharmananda, Subhuti, Ph.D., “A Bag of Pearls” Portland, OR: Institute for Traditional Medicine, 2002
Dharmananda, Subhuti, Ph.D., “Checking for Possible Herb-Drug Interactions” Portland, OR: Institute for Traditional Medicine, Sept. 2003
Dharmananda, Subhuti, Ph.D., “Controlled Clinical Trials of Chinese Herbal Medicines: A Review” Portland, OR: Institute for Traditional Medicine, Dec.1997
Dharmananda, Subhuti, Ph.D., “Did the Herbs Cause That” Portland, OR: Institute for Traditional Medicine, May 2001
Dharmananda, Subhuti, Ph.D., “Do Herbs, Vitamins and Antioxidants Adversely Affect Cancer Therapies?” Portland, OR: Inst for Traditional Med., Dec. 2002
Dharmananda, Subhuti, Ph.D., “Drugs in Imported Chinese Herb Products” Portland, OR: Institute for Traditional Medicine, Nov. 1996
Dharmananda, Subhuti, Ph.D., “How Clean and Pure are Chinese Herbs?” Portland, OR: Institute for Traditional Medicine, March 2002
Dharmananda, Subhuti, Ph.D., “Responding to Concerns about Herb-Drug Interactions” A Bag of Pearls: 2001 Update, Portland, OR: Inst. for Trad. Med.
Dharmananda, Subhuti, Ph.D., “Safety Issues Affecting Chinese Herbs: (7 articles) “Magnolia alkaloids” (2000); “The Case of Asarum” (Aug. 2000); “The Case of Ma-huang” (Dec. 2000); “The Case of Kava” (March 2002); “The Case of Xanthium” (Dec. 2002); “The Case of Dictamnus and Herbs for Skin Diseases” (April 2003); “Herbs That May Increase Blood Pressure” (Sept. 2003)
Dharmananda, Subhuti, Ph.D., “Safety Issues Affecting Herbs: (3 articles) “Pyrrolizidine Alkaloids” (Nov. 2001); “How Long can Stimulant Laxatives be Used?” (March 2002); “Herbs That May Increase Blood Pressure” (Sept. 2003)
Dharmananda, Subhuti, Ph.D., “The Interactions of Herbs and Drugs” Portland, OR: Institute for Traditional Medicine, Dec. 2000
Dharmananda, Subhuti, Ph.D., “The Methods of Preparation of Herb Formulas: Decoctions, Dried Decoctions, Powders, Pills, Tablets and Tinctures” Portland, OR: Institute for Traditional Medicine, May 1997
Entrez-PubMed website: http://www.ncbi.nlm.nih.gov/PubMed/
Ernst, E, “St. John’s Wort supplements endanger the success of organ transplantation” Arch Surg 2002 Mar; 137(3):316-9
Ernst, E & MH Pittler, “The efficacy and safety of feverfew (Tanacetum parthenium L.): an update of a systematic review” Public Health Nutr 2000 Dec;3(4A):509-14
Fetrow, Charles W., Pharm D. & Juan R. Avila, Pharm D, The Complete Guide to Herbal Medicine, New York: Simon & Schuster, 2000
Fetrow, Charles W., Pharm D. & Juan R. Avila, Pharm D, Professional’s Handbook of Complementary & Alternative Medicines, Philadelphia: Lippincott Williams & Wilkins, 2004
Foster, Steven, “It’s ‘Official’ – If It’s in the USP”, Herbs for Health, July/Aug. 2003: 56-58
Fugh-Berman, A, “Herb-drug interactions” Lancet 2000 Jan 8;355(9198):134-8
Goldman, Peter, MD, “Herbal Medicines Today and the Roots of Modern Pharmacology” Ann Intern Med 2001 Oct.;135(8 Pt 1):594-600
Harkey, MR et al, “Variability in commercial ginseng products: an analysis of 25 preparations” Am J Clin Nutr 2001 Jun;73(6):1101-6
Harkness, Richard, Pharm., FASCP & Steven Bratman, M.D. Drug-Herb Interactions Bible, Prima Publishing, 2000
Harvey, Richard A. and Pamela C. Champe (Editors) Lippincott’s Illustrated Reviews: Pharmacology, Philadelphia: J. B. Lippincott Co., 1992
Henderson, L et al, “St. John’s wort (Hypericum perforatum): drug interactions and clinical outcomes” Br J Clin Pharmacol 2002 Oct;54(4):349-56
Huntley, A & E Ernst, “A systematic review of the safety of black cohosh” Menopause, 2003 Jan-Feb;10(1):58-64
Ioannides, C., “Pharmacokinetic interactions between herbal remedies and medicinal drugs.” Xenobiotica 2002 Jun;32(6):451-78
Izzo AA, “Drug interactions with St. John’s Wort (Hypericum perforatum): a review of the clinical evidence” Int J Clin Pharmacol Ther 2004 Mar;42(3):139-48
Izzo, A.A. and E. Ernst, “Interactions between herbal medicines and prescribed drugs: a systematic review” Drugs, 2001;61(15):2163-75
Lust, John, N.D., D.B.M., The Herb Book, Simi Valley, CA: Benedict Lust Publications, 1974
Maciocia, Giovanni, The Practice of Chinese Medicine, Edinburgh: Churchill Livingstone, 1994
Markowitz JS & CL DeVane, “The emerging recognition of herb-drug interactions with a focus on ST. John’s wort (Hypericum perforatum, Psychopharmacol Bull. 2001 Winter,35(1):53-64
Martin, J. & J. Dusek, “The Baikal skullcap (Scutellaria baicalensis Georgi) – a potential source of new drugs” (Article in Czech) Ceska Slov Farm. 2002 Nov;51(6):277-83
McCullough, Lynda, “Find the best herbal research” Herbs for Health, May/June 2000, p. 12
Miller, LG, “Herbal medicinals: selected clinical considerations focusing on known or potential drug-herb interactions.” Arch Intern Med. 1998 Nov 9;158(20):2200-11
Mindell, Earl, R.Ph, Ph.D., & Virginia Hopkins, Prescription Alternatives, New Canaan, CT: Keats Publ, 1998
Murray, Lori (Sr. Ed.), Physicians’ Desk Reference 58th Edition, Montvale, NJ: Thomson PDR 2004
Naeser, Margaret A, Ph.D., Outline Guide to Chinese Herbal Patent Medicines in Pill Form, Boston: Boston Chinese Medicine, 1992
Nakagawa A et al, “Five cases of drug-induced pneumonitis due to Sho-saiko-to or interferon-alpha or both” Nihon Kyobu Shikkan Gakkai Zasshi. 1995 Dec;33(12):13361-1366
Pierce, Andrea The American Pharmaceutical Association Practical Guide to Natural Medicines, New York: Wm. Morrow & Co., 1999
Rountree, Robert, M.D., “Herb-drug mix” Herbs for Health, Jan/Feb 2001 pp. 26-27
Rountree, Robert, M.D., “Potential Herb-drug Interactions” Herbs for Health, Jan/Feb 2001 pp.40-41
Skidmore-Roth, Linda, Mosby’s Handbook of Herbs & Natural Supplements, 2nd edition, St. Louis: Mosby, Inc., 2004
Sparreboom A et al, “Herbal remedies in the United States: potential adverse interactions with anticancer agents” j Clin Oncol 2004 Jun 15;22(12):2489-503
Spinella, Marcello Ph.D., “The Importance of Pharmacological Synergy in Psychoactive Herbal Medicines” Alternative Medicine Review, Vol. 7, No. 2, 2002 130-137
Smolinske, SC, “Dietary supplement-drug interactions”, J Am Med Women’s Assoc. 1999 Fall;54(4):191-2,195
Stedman’s Medical Dictionary, 27th Edition. Philadelphia: Lippincott Williams & Wilkins, 2000
Stux, G and R. Hammerschlag (Eds.) Clinical Acupuncture: Scientific Basis, Berlin: Springer-Verlag, 2001
Tesch, BJ, “Herbs commonly used by women: an evidence-based review” Dis Mon 2002 Oct;48(10):671-96
Thompson-Coon JS & E Ernst, “Herbs for serum cholesterol reduction: a systematic review” J Fam Pract. 2003 Jun;52(6):468-78
Tierra, Michael, C.A., N.D., The Way of Herbs, New York: Simon & Schuster, 1990
Vuksan, V. et al, “American ginseng (Panax quinquefolius L.) attenuates postprandial glycemia in a time-dependent but not dose-dependent manner in healthy individuals”, Am J Clin Nutr2001;73:753-8
Vuksan, V. et al “American Ginseng Improves Glycemia in Individuals with Normal Glucose Tolerance; Effect of Dose and Time Escalation” J Am Coll Nutr 2000 Nov-Dec;19(6):738-44
Weil, Andrew, M.D., “When Herbs and Drugs Don’t Mix” Self Healing, Premier Issue, 2004: 8
Weil, Andrew, M.D., “Coping with Chemotherapy and Radiation” Self Healing, July 2004: 5
Weil, Andrew, M.D., “Got Milk Thistle?” Self Healing, August 2004: 3
Williamson, E.M., “Drug interactions between herbal and prescription medicines.” Drug Saf 2003;26(15):1075-92
Yance, Donald R, Jr., C.N., M.H., A.H.G., Herbal Medicine, Healing & Cancer, Chicago: Keats Publishing, 1999
Yeh, Gloria et al, “Systematic Review of Herbs and Dietary Supplements for Glycemic Control in Diabetes” Diabetes Care, Vol 26, No 4, Apr 2003 1277-1294
Yeung, Him-che, O.M.D., Ph.D., Handbook of Chinese Herbal Formulas, Rosemead: Institute of Chinese Medicine, 1995
Yeung, Him-che, O.M.D., Ph.D., Handbook of Chinese Herbs, Rosemead: Institute of Chinese Medicine, 1996
Yuan, Chun-Su et al, “Brief Communication: American Ginseng Reduces Warfarin’s Effect in Healthy Patients”, Ann Intern Med 6 July 2004, Vol 141, Issue 1, pages 23-27
[i] Skidmore-Roth, Linda, Mosby’s Handbook of Herbs & Natural Supplements, 2nd edition, St. Louis: Mosby, Inc., 2004
[ii] Calixto, J.B. “Efficacy, safety, quality control, marketing and regulatory guidelines for herbal medicines (phytotherapeutic agents), Brazilian Journal of Medical and Biological Research, (2000) 33:179-189
[iii] Smolinske, SC, “Dietary supplement-drug interactions”, J Am Med Women’s Assoc. 1999 Fall;54(4):191-2,195
[iv] Goldman, Peter, MD, “Herbal Medicines Today and the Roots of Modern Pharmacology” Ann Intern Med 2001 Oct.;135(8 Pt 1):594-600
[v] Bensky, Dan & Andrew Gamble, Chinese Herbal Medicine: Materia Medica, Seattle: Eastland Press, 1986
[vi] Bensky, Dan & Andrew Gamble, Chinese Herbal Medicine: Materia Medica, Seattle: Eastland Press, 1986
[vii] Calixto, J.B. “Efficacy, safety, quality control, marketing and regulatory guidelines for herbal medicines (phytotherapeutic agents), Brazilian Journal of Medical and Biological Research, (2000) 33:179-189
[viii] Skidmore-Roth, Linda, Mosby’s Handbook of Herbs & Natural Supplements, 2nd edition, St. Louis: Mosby, Inc., 2004
[ix] Yeh, Gloria Y et al, “Systematic Review of Herbs and Dietary Supplements for Glycemic Control in Diabetes” Diabetes Care, Vol 26, No. 4, April 2003 1277-1294
[x] Stux, G and R. Hammerschlag (Eds.) Clinical Acupuncture: Scientific Basis, Berlin: Springer-Verlag, 2001
[xi] Coon, JT & E Ernst, “Panax ginseng: a systematic review of adverse effects and drug interactions” Drug Saf 2002;25(5):323-44
[xii] Dharmananda, Subhuti, Ph.D., “Checking for Possible Herb-Drug Interactions” Portland, OR: Institute for Traditional Medicine, Sept. 2003
[xiii] Dharmananda, Subhuti, Ph.D., “A Bag of Pearls” Portland, OR: Inst. for Traditional Medicine, 2002: 63-64
[xiv] Weil, Andrew, M.D., “When Herbs and Drugs Don’t Mix” Self Healing, Premier Issue, 2004: 8
[xv] Bratman, Steven, MD & Andrea M. Girman, MD MPH, Mosby’s Handbook of Herbs and Supplements and their Therapeutic Uses, St Louis: Mosby, 2003
[xvi] Fetrow, Charles W., Pharm D. & Juan R. Avila, Pharm D, Professional’s Handbook of Complementary & Alternative Medicines, Philadelphia: Lippincott Williams & Wilkins, 2004
[xvii] Harkness, Richard, Pharm., FASCP & Steven Bratman, M.D. Drug-Herb Interactions Bible, Prima Publishing, 2000
[xviii] Skidmore-Roth, Linda, Mosby’s Handbook of Herbs & Natural Supplements, 2nd edition, St. Louis: Mosby, Inc., 2004
[xix] Rountree, Robert, M.D., “Potential Herb-drug Interactions” Herbs for Health, Jan/Feb 2001: 40-41
[xx] Dharmananda, Subhuti, Ph.D., “Responding to Concerns about Herb-Drug Interactions” A Bag of Pearls: 2001 Update, Portland, OR: Institute for Traditional Medicine
[xxi] Dharmananda, Subhuti, Ph.D., “Checking for Possible Herb-Drug Interactions” Portland, OR: Institute for Traditional Medicine, Sept. 2003
[xxii] Abebe, W, “Herbal medication: a potential for adverse interactions with analgesic drugs” J Clin Pharm Ther 2002 Dec;27(6):391-401
[xxiii] Abebe, W, “Herbal medication: a potential for adverse interactions with analgesic drugs” J Clin Pharm Ther 2002 Dec;27(6):391-401
[xxiv] Abebe, W, “Herbal medication: a potential for adverse interactions with analgesic drugs” J Clin Pharm Ther 2002 Dec;27(6):391-401
[xxv] Miller, LG, “Herbal medicinals: selected clinical considerations focusing on known or potential drug-herb interactions.” Arch Intern Med. 1998 Nov 9;158(20):2200-11
[xxvi] Weil, Andrew, M.D., “Coping with Chemotherapy and Radiation” Self Healing, July 2004: 5
[xxvii] Miller, LG, “Herbal medicinals: selected clinical considerations focusing on known or potential drug-herb interactions.” Arch Intern Med. 1998 Nov 9;158(20):2200-11
[xxviii] Abebe, W, “Herbal medication: a potential for adverse interactions with analgesic drugs” J Clin Pharm Ther 2002 Dec;27(6):391-401
[xxix] Miller, LG, “Herbal medicinals: selected clinical considerations focusing on known or potential drug-herb interactions.” Arch Intern Med. 1998 Nov 9;158(20):2200-11
[xxx] Abebe, W, “Herbal medication: a potential for adverse interactions with analgesic drugs” J Clin Pharm Ther 2002 Dec;27(6):391-401
[xxxi] Abebe, W, “Herbal medication: a potential for adverse interactions with analgesic drugs” J Clin Pharm Ther 2002 Dec;27(6):391-401
[xxxii] Weil, Andrew, M.D., “Got Milk Thistle?” Self Healing, August 2004: 3
[xxxiii] Nakagawa A et al, “Five cases of drug-induced pneumonitis due to Sho-saiko-to or interferon-alpha or both” Nihon Kyobu Shikkan Gakkai Zasshi. 1995 Dec;33(12):13361-1366
[xxxiv] Ioannides, C., “Pharmacokinetic interactions between herbal remedies and medicinal drugs.” Xenobiotica 2002 Jun;32(6):451-78
[xxxv] McCullough, Lynda, “Find the best herbal research” Herbs for Health, May/June 2000: 12
[xxxvi] Calixto, J.B. “Efficacy, safety, quality control, marketing and regulatory guidelines for herbal medicines (phytotherapeutic agents), Brazilian Journal of Medical and Biological Research, (2000) 33:179-189
[xxxvii] Goldman, Peter, MD, “Herbal Medicines Today and the Roots of Modern Pharmacology” Ann Intern Med 2001 Oct.;135(8 Pt 1):594-600
[xxxviii] Yeung, Him-che, O.M.D., Ph.D., Handbook of Chinese Herbs, Rosemead: Institute of Chinese Medicine, 1996: 26-30
[xxxix] Dharmananda, Subhuti, Ph.D., “A Bag of Pearls” Portland, OR: Inst. for Traditional Medicine, 2002: 19
[xl] Dharmananda, Subhuti, Ph.D., “A Bag of Pearls” Portland, OR: Inst. for Traditional Medicine, 2002: 60-61
The Food and Drug Administration has not approved the use of any of the natural treatments discussed in this article. This article and the information contained herein on herbs and supplements has not been approved by the Food and Drug Administration. The herbs or supplements discussed in this article are not intended to be used to diagnose or treat any medical condition.
NONE of the herbs or supplements mentioned in this article should be used internally by persons who are pregnant or lactating and should NOT be given to children.
* * *
TABLE OF CONTENTS
1. Introduction
2. Setting Standards to Achieve Consistent Herbal Formulations
3. Systematic Reviews On Herb-Drug Interactions
4. Herb-Drug and Supplement-Drug Interactions
5. Interactions by Category of Drug
6. Interactions by Herb or Supplement
7. Towards a Better Understanding of Herbs and Drugs
8. Chemical Components of Herbs
9. References
10. Text Citations
1. INTRODUCTION
Barbara and I treat our patients using a combination of acupuncture and craniosacral therapy; and when indicated we use herbs and nutritional supplements to compliment our treatments. We have written this article/review so that you may be more informed of the possible interactions that might occur between the herbs or supplements and any drugs you may be taking. We hope you find it helpful.
In the last 10 to 20 years interest in natural therapies, especially herbal medicine has increased dramatically. Of all the alternative modalities herbal medicine is probably the most popular and the most ubiquitous. A study published four years ago found that 61% of elderly Hispanic and non-Hispanic white patients had used herbal remedies. An earlier study published in 1997 found that 34% of adult Americans had used herbal remedies. According to a national survey, about 60 million Americans over 18 years of age use herbal medicines to treat colds, burns, headaches, allergies, rashes, depression, diarrhea and menopause, among other conditions. The problem is that many people use prescription drugs concurrently with herbal remedies and as a result face possible health risks due to adverse reactions.[i] & [ii]
Recent surveys show that 18% of adults in the United States use prescription drugs concurrently with herbal or vitamin products, placing an estimated 15 million patients at risk of potential drug-supplement interactions.[iii] Indeed, half of the herbs taken by patients are not reported to their physicians. [iv]
2. SETTING STANDARDS TO ACHIEVE CONSISTENT HERBAL FORMULATIONS
Since the early 19th century attempts have been made to understand the actions and properties of traditional Chinese medicinal substances through scientific research. Due to the fact that herbs are composed of a multitude of ingredients whose interactions with the body are exceedingly complex a high level of sophistication of research methodology is necessary to describe these interactions. Only recently has such a rigorous methodology begun to be developed. [v]
Herbal medicines and natural supplements differ from synthetic drugs in the following ways:
Many herbs have no known active ingredients, and for most of the herbs of which some of the active ingredients are known little is understood of their pharmacokinetics. [vi]
Plants contain several hundred constituents and some of them are present at very low concentrations. In spite of the modern chemical analytical procedures available, only rarely do phytochemical investigations succeed in isolating and characterizing all secondary metabolites present in the plant extract.
Standardization, stability and quality control are feasible for patented supplement brands, but it is not as easy to achieve as it sounds. The availability and quality of raw materials can be problematic, especially during shortages.
Plant and supplement constituents vary considerably depending upon: the source and quality of the raw materials, the use of fresh plants, temperature, light exposure, the method of collecting, drying, packing, storage and transportation of the raw material, age and part of the plant collected as well as the possibility of contamination with microorganisms, heavy metals, and pesticides. No two brands are the same.
There are not many well-controlled double-blind clinical and toxicological studies to prove the efficacy and safety of herbal medicines. They have a wide range of therapeutic use and are suitable for chronic treatments. However, the occurrence of undesirable side effects seems to be less frequent with herbal medicines and they usually cost less than synthetic hormones or drugs. [vii]
What is a “Standardized Extract“? When you read the label on a bottle of herbs you will often see the words “Standardized Extract”. A standardized extract contains not only the active chemical constituent to which the extract has been standardized, but also the other components of the herb. Research has shown that using the isolated active component alone often does not produce the same therapeutic effect as does using a preparation containing all of the components together. This so-called synergistic action of herbs is not yet fully understood. Proponents of herbal remedies caution that in standardizing to one constituent resulting extracts may lose a proportion of benefit as compared with the whole plant. The use of standardized products, however, currently provides the greatest assurance of receiving an accurate, reliable dose of the active constituents of an herb, and of safely achieving the desired therapeutic effect.[viii] [ix]
3. SYSTEMATIC REVIEWS ON HERB-DRUG INTERACTIONS
In order to appreciate how modern science is approaching the question of herb-drug interactions we thought it would be instructive to include some scientific studies so you can see how scientists are tackling these issues. The gold standards for assessing efficacy and safety are large, well-designed, randomized controlled trials (RCTs) and systematic reviews. Systematic reviews require that all trials that meet specified criteria must be included in the review, regardless of the trial results. In the midst of the information explosion clinicians rank reviews as their most preferred source of new information. [x] Although there may indeed be more published systematic reviews on herb-drug interactions by now, when we conducted our Medline search we only found one. It is as follows:
Coon and Ernst (2002) conducted a systematic review on the adverse effects and drug interactions of Panax ginseng. Systematic searches were performed in five electronic databases and the reference lists of all papers located were checked for further relevant publications. Data from the clinical trials suggest that the incidence of adverse events with ginseng monopreparations is similar to that with placebo. The most commonly experienced adverse events are headache, sleep and gastrointestinal disorders. Combination products containing ginseng as one of several constituents have been associated with serious adverse events and even fatalities. Interpretation of these cases is difficult, as ingredients other than P. ginseng may have caused the problems. Possible drug interactions have been reported between P. ginseng and warfarin, phenelzine and alcohol. Collectively, these data suggest that P. ginseng monopreparations are rarely associated with adverse events or drug interactions. [xi]
4. HERB-DRUG AND SUPPLEMENT-DRUG INTERACTIONS
Useful Tips To Help Minimize Herb Drug Interactions
According to Subhuti Dharmananda, a highly respected Chinese herbalist, the nature of herb-drug interactions is not a chemical interaction between a drug and an herb component to produce something toxic. Instead, the interaction may involve having an herb component cause either an increase or decrease in the amount of drug in the blood stream. The following suggestions from Subhuti Dharmananda are useful to help avoid potential herb-drug interactions:
v Taking herbs at least 1 hrs apart from taking drugs is a very good idea.
v For example, tetracycline can bind with minerals in the herbs inhibiting their absorption resulting in low drug levels.
v Pectins, resins and fibers in herbs may bind several drugs inhibiting their absorption resulting in low drug levels. v Herbs can modify drug absorption and/or elimination. For example, saponins may improve absorption and elimination of drugs, altering the blood levels and rate of change of drug levels.
v Another good reason to take herbs at least 1 hours apart from drugs, preferably taking the drugs first, is so that drug metabolism is already underway by the time the herbs can inhibit enzyme systems. For example grapefruit juice and herbs such as angelica, that inhibit the CYP enzyme system, can result in much higher levels of drugs in the bloodstream and longer persistence of the drugs. Saponins in herbs may improve absorption and elimination of drugs, altering the blood levels and rate of change of drug levels.
v Avoid using herbs with strong laxative or diuretic action while using cardiac drugs. To compensate for mild diuretic or laxative treatments, consume high-potassium foods.
v When the drug therapy is already addressing a particular therapeutic goal, avoid adding a potent herbal therapy with the same goal. Intensify monitoring of blood conditions affected by the drugs.
v Learn the known drug reactions and take reasonable steps to avoid problematic herbs. For example, MAO inhibitors can cause hypertension when an ordinary food component, tyramine is ingested.
v Learn the known herb-drug interactions and avoid using the combinations, if necessary.
v For example, avoid mixing herbs or supplements and drugs that have similar actions. For example, gingko has blood-thinning properties and may heighten the effects of anticoagulant drugs.
v Conversely, you should avoid mixing herbs or supplements and drugs that have opposite actions. For example, ephedra can exacerbate high blood pressure and may cancel out the effects of antihypertensive drugs. [xii] [xiii] [xiv]
We hope the following lists of reported or suspected herb and supplement-drug interactions will help give you a better understanding of when you can or cannot take certain herbs and drugs together and why. This list is by no means exhaustive or complete. In the listing of interactions by category of drug we sometimes give examples of drugs found in certain categories. There may be quite a number of different drugs in these categories, but we have only listed some of the more familiar ones. So if you don’t find certain drugs in the examples we have given it doesn’t mean they are not included in that particular category. As information on herb/supplement-drug interactions continues to be published we will endeavor to update it.
The herb-drug interactions have been classified in two ways: 1) Category of Drug and 2) Herb or Supplement. Both sections are listed alphabetically.
Key to references consulted for herb-drug and supplement-drug interactions cited below unless otherwise specified:
FA= Fetrow, Charles W., Pharm D. & Juan R. Avila, Pharm D, Professional’s Handbook of Complementary & Alternative Medicines[xvi]
HB= Harkness, Richard & Steven Bratman, M.D. Drug-Herb Interactions Bible [xvii]
LSR = Skidmore-Roth, Linda, Mosby’s Handbook of Herbs & Natural Supplements [xviii]
RR = Rountree, Robert, M.D., “Potential Herb-drug Interactions” Herbs for Health [xix]
SD = Dharmananda, Subhuti, Ph.D., “Responding to Concerns about Herb-Drug Interactions” [xx]
SDh = Dharmananda, Subhuti, Ph.D., “Checking for Possible Herb-Drug Interactions”[xxi]
5. INTERACTIONS BY CATEGORY OF DRUG
v Iron supplements can interfere with the absorption of captopril and perhaps other ACE inhibitors. To minimize any potential problems take iron supplements and ACE inhibitors 2 to 3 hours apart. (HB)
v Licorice. Whole licorice can cause sodium retention and increase blood pressure, thus counteracting the intended effects of ACE inhibitors. DGL (deglycyrrhizinated licorice) is an altered form of the herb that should not cause these problems. (HB)
v Magnesium can interfere with absorption ACE inhibitors. To avoid this problem, magnesium should be taken at least 2 hours before or after taking these drugs. (BG)
v Potassium may interact with ACE inhibitors by causing irregular heart rhythm, muscle weakness, nausea, vomiting, irritability and diarrhea by increasing potassium levels in the blood even higher. (ACE inhibitors cause the body to retain more potassium than usual.) (HB)
Acetaminophen (Tylenol, Midol, Excedrin PM)
v Vitamin C, according to one study, at very high doses (3 g daily) might increase serum levels of acetaminophen. This could possibly allow the drug to accumulate to levels that may damage the liver. (BG & HB)
v Echinacea when combined with acetaminophen may result in increased incidences of hepatotoxicity and nephrotoxicity. [xxii]
v Kava when combined with acetaminophen may result in increased incidences of hepatotoxicity and nephrotoxicity. [xxiii]
v Ginkgo may interact with acetaminophen to increase the risk of bleeding. [xxiv]
Acne medication (Accutane)
v Vitamin A might interact with Accutane by increasing each other’s toxicity due to their structural similarities. (HB)
Alcohol
v Arginine when used in higher doses may increase the risk of gastric irritation when combined with alcohol. (BG)
v Betel Palm (Areca catechu) (pan parag) increases the effects of alcohol; do not use concurrently. (LSR)
v Hawthorn may increase the sedative effects of CNS depressants such as alcohol; avoid concurrent use. (LSR)
v Kava High doses of alcohol increased the effects and toxicity of kava in mice. (BG)
v Scutellaria baicalensis may increase sedation of CNS depressants; avoid concurrent use. (LSR)
v Valerian may enhance the effects of alcohol. (RR & BG)
v Valerian may increase the effects of CNS depressants; avoid concurrent use. (LSR)
All drugs
v Fenugreek may cause reduced absorption of all medications used concurrently. (LSR)
v Flax may cause a decrease in the absorption of all oral medications if taken concurrently with flax. (LSR)
v Ginger may increase absorption of all medications taken orally. (LSR)
v Pectin decreases absorption of all drugs, vitamins and minerals if taken concurrently. (LSR)
All oral drugs
v Flax may decrease absorption of all medications taken orally. (LSR)
v Ginger may increase absorption of all medications taken orally. (LSR)
v Marshmallow may reduce the absorption of oral medications; do not use concurrently. (LSR)
Alpha-adrenergic blockers (Cardura)
v Butcher’s Broom may decrease the action of alpha-adrenergic blockers, therefore avoid concurrent use. (LSR)
v Capsicum peppers may decrease the action of alpha-adrenergic blockers, therefore avoid concurrent use. (LSR)
v Yohimbe taken along with alpha-adrenergic blockers may result in increased toxicity, therefore avoid concurrent use. (LSR)
Anti-anginals
v Blue Cohosh may decrease the action of antianginals, causing chest pain so do not use concurrently. (LSR)
Anti-anxiety drugs (Benzodiazepines) (E.g., Xanax, Librium, Tranxene, Valium, Paxipam)
v Grapefruit juice slows the body’s normal breakdown of benzodiazepines, allowing them to build up to potentially dangerous levels in the blood. Therefore avoid grapefruit juice altogether if taking benzodiazepines. (LSR)
v Kava combined with alprazolam resulted in one case of a man being hospitalized for lethargy and disorientation. Experimental studies suggest that kava exerts is sedative effects similarly to benzodiazepines therefore combining kava with benzodiazepine drugs could result in “add-on” or excessive physical depression, sedation and impairment. Therefore avoid combining kava with benzodiazepines. (LSR)
v Melatonin may increase the anxiolytic effects of benzodiazepines; use together cautiously. (LSR)
v Ashwagandha, hops, lemon balm, passionflower, skullcap and valerian and other herbs with sedative effects might cause problems when combined with benzodiazepines. Avoid combining these herbs with benzodiazepines for this reason. (LSR)
Anti-arrhythmic drugs (Quinidine)
v Aloe can cause hypokalemia (lowered blood potassium levels) thereby enhancing the effects of anti-arrhythmic agents. (SD)
v Chinese rhubarb used chronically can cause hypokalemia (lowered blood potassium levels) and enhance the effects of anti-arrhythmic drugs. (SD & LSR)
v Goldenseal may increase the effects of anti-arrhythmic drugs. (LSR)
v Hawthorn may interact with or potentiate other cardiovascular drugs and such combinations should be used with caution. (BG)
v Licorice increases the cardiac effects of anti-arrhythmic drugs and therefore do not use concurrently. (LSR)
v Scrophularia nodosa may increase the effects of antiarrhythmics and beta-blockers; do not use concurrently. (LSR)
v Senna may interact with quinidine causing irregular heartbeats from low blood potassium because long-term use increases the loss of potassium from the stool as a result of laxative effect. (RR)
Anti-asthma drugs (theophylline)
v Arginine when used in higher doses may increase the risk of gastric irritation when combined with theophylline. (BG)
v Ipriflavone appears to slow the body’s normal breakdown of theophylline to inactive forms, allowing the drug to build up in the blood. This may increase the risk of toxic symptoms such as nervousness and even seizures. Therefore avoid using ipriflavone when taking theophylline. (HB)
v St. John’s wort lowers blood levels of theophylline causing a worsening of asthma symptoms. Therefore you should not combine St. John’s wort and theophylline. (RR & HB)
Antibiotics (fluoroquinolones, ciprofloxacin, nitrofurantoin, TMP-SMZ antibiotics such as Bactrim, Septra, Cotrim and Sulfatrim)
v Cranberry Theoretically some antibiotics could be inhibited by the reduced urinary pH caused by cranberry. (BG)
v Fennel appears to reduce blood levels of ciprofloxacin, possibly impairing its effectiveness. (HB)
v Iron supplements may inhibit the absorption of antibiotics in the tetracycline and quinolone families. Separating intake of the iron and drugs by at least 2 hours is likely to forestall any absorption problem. (BG)
v Magnesium can interfere with absorption of antibiotics in the tetracycline and fluoroquinolones families. To avoid this problem, magnesium should be taken at least 2 hours before or after taking these drugs. (BG)
v Zinc supplements can interfere with the absorption of tetracyclines, fluoroquinolones and penicillamine. (BG)
Anti-coagulants (Blood thinners) (Coumadin, Miradon, anisindione, dicumarol, heparin, warfarin)
Platelet Inhibitors (clopidogrel, ticlodipine)
v Alfalfa due to its high vitamin K content could, in theory, reduce the effectiveness of anticoagulants; avoid concurrent use. (HB)
v Arginine when used in higher doses may increase the risk of gastric irritation when combined with platelet inhibitors. (BG)
v Bilberry may increase the action of anticoagulants and antiplatelet agents; use caution if taking concurrently. (LSR)
v Chondroitin used with anticoagulants can cause increased bleeding. Do not use concurrently. (LSR)
v CoQ10 may decrease the action of anticoagulants; avoid concurrent use. (LSR)
v Cramp Bark (Black Haw) increases the action of anticoagulants; do not use concurrently. (LSR)
v Curcumin may result in an increased risk of bleeding if used with anticoagulants or NSAIDs; avoid concurrent use.(LSR)
v Dandelion leaf extract contains coumarins; therefore theoretically it could interact with anti-coagulants enhancing their effects. (BG)
v Dong quai (Angelica) interacts with warfarin to cause bleeding (SD) Dong Quai may interact with warfarin (BG) and it may increase the effects of antiplatelets and oral anticoagulants. Avoid the concurrent use of angelica with all anticoagulants. (LSR)
v Fenugreek taken concurrently with anticoagulants may cause an increased risk of bleeding. (LSR)
v Feverfew might potentially interact with anticoagulants because of its antiplatelet activity. (BG)
v Fish Oil Although fish oil does not appear to increase the bleeding complications caused by aspirin, interactions with anticoagulants such as warfarin have not been ruled out. (BG)
v Garlic interacts with warfarin to cause bleeding. (SD)
v Garlic interacts with warfarin causing increased bleeding by inhibiting platelet aggregation. (RR)
v Garlic has a blood thinning effect and therefore may be dangerous to take along with heparin. (HB)
v Garlic appears to possess anti-thrombotic activity and should be used with caution in patients on anticoagulants. (BG)
v Ginger should be used with care in patients using anticoagulants or antiplatelet agents because of its effects on platelet action. (BG)
v Gingko interacts with warfarin causing increased risk of bleeding by inhibiting platelet aggregation factor. (RR)
v Gingko has a blood thinning effect and therefore may be dangerous to take along with heparin (HB) and anticoagulants and antiplatelet agents. (LSR)
v Ginkgo is known to inhibit platelet activation factor and for this reason it is advisable to use caution when combining ginkgo with warfarin, heparin, aspirin or any other drugs with anticoagulant or antiplatelet effects. One case report suggests a probable interaction between ginkgo and aspirin. (BG)
v Ginseng may decrease the action of anticoagulants. (LSR)v
v Ginseng (Panax) interacts with warfarin to cause bleeding or to decrease effectiveness. (SD)
v Goldenseal may decrease the action of anticoagulants; do not use concurrently. (LSR)
v Green tea contains vitamin K, and large doses could potentially interfere with the effectiveness of anticoagulants.(BG)
v Horse Chestnut could theoretically interfere with anticoagulants because of the coumarins in it. (BG)
v Kelp used along with anticoagulants may pose an increased risk of bleeding; avoid concurrent use. (LSR)
v Nettle may decrease the effect of anticoagulants; avoid concurrent use. (LSR)
v OPCs (Grape Seed Extract) might (based on the activity of other flavonoids) potentiate anticoagulant and antiplatelet agents. (BG)
v Oxerutins theoretically might potentiate anticoagulants. (BG)
v Papain might potentiate anticoagulv ant and antiplatelet agents. (BG)
v Pau d’arco when combined with anticoagulants may result in an increased risk of bleeding; avoid concurrent use (theoretical). (LSR)
v Phosphatidylserine In vitro studies report that fatty acid esters of phosphatidylserine and phosphatidylethanolamine can synergistically stimulate the anticoagulant effect of heparin. (BG)
v Policosanol appears to potentiate the antiplatelet effects of aspirin. For this reason, caution should be exercised when combining policosanol with any antiplatelet or anticoagulant agent. (BG)
v Quercetin because of quercetin’s effects on platelet aggregation, interactions with antiplatelet and anticoagulant drugs could occur. (BG)
v Reishi (Ganoderma) could theoretically interfere with anticoagulants because of the constituents in it. (LSR)v v v Salvia (Danshen) interacts with warfarin to cause bleeding. (SD)
v Saw Palmetto may increase the anticoagulant effects of anticoagulants, antiplatelets and NSAIDs leading to increased bleeding time; avoid concurrent use. (LSR)
v St. John’s wort may interact with warfarin causing increased risk of blood clots by lowering blood levels of warfarin. (RR)
v Turmeric used along with anticoagulants may result in an increased risk of bleeding; avoid concurrent use. (LSR)
v Vinpocetine may impair the effectiveness of warfarin. (BG)
v Vitamin A may increase the anticoagulant effects of warfarin. (BG)
v Vitamin C might reduce the effects of warfarin and heparin according to weak evidence. (BG)
v Vitamin E might potentiate anticoagulant or antiplatelet medications based on its anticoagulant properties. (BG)
v Vitamin K antagonizes the action of warfarin. (BG)
v White willow also known as willow bark contains a substance that is converted by the body into a Salicylate similarto aspirin. Since combining aspirin with heparin increases the risk of abnormal bleeding, it would be advisable not to combine white willow with heparin. (HB)
Anti-convulsant drugs (phenobarbital, Phenytoin, Dilantin, Primidone, Mysoline, Carbamazepine, Valproic Acid, Keppra, Neurontin, Trileptal, Klonopin)
v Borage and Evening Primrose Oil should not be used with anticonvulsants because they may lower the seizure threshold. [xxv]
v Folate (Folic Acid) may increase seizures in individuals with epilepsy and may interfere with phenytoin therapy. (BG)
v Ginkgo components may decrease the anticonvulsant effect; avoid concurrent use. (LSR)
v Ginseng may provide an additive anticonvulsant action (theoretical). (LSR)
v Glutamine Theoretically, high doses of glutamine may overwhelm anticonvulsant drugs and pose a risk to individuals with seizure disorders because many of them work by blocking glutamine stimulation in the brain. (BG)
v Hawthorn may increase the sedative effects of CNS depressants such as barbiturates; avoid concurrent use. (LSR)
v Kava taken with barbiturates may result in increased sedation. (LSR)
v Lemon Balm may increase the sedative effects of barbiturates and CNS depressants. (LSR)
v Magnesium can interfere with absorption of phenytoin. To avoid this problem, magnesium should be taken atleast 2 hours before or after taking these drugs. (BG)
v Sage may decrease the action of anticonvulsants; avoid concurrent use (theoretical). (LSR)
v Scutellaria baicalensis may increase sedation of CNS depressants; avoid concurrent use. (LSR)
v Valerian may increase the effects of CNS depressants; avoid concurrent use. (LSR)
v Vitamin B3 (Niacin) might increase serum levels of anticonvulsant medications including carbamazepine and primidone, possibly requiring reduction in drug dosage. (BG)
Anti-depressants (MAO inhibitors, phenelzine sulfate, amitriptyline, Elavil, Wellbutrin, Celexa, Prozac, Zoloft, Paxil, Effexor)
v Cranberry Blood levels of antidepressants can be reduced by excessive use of cranberry juice. (BG)
v Ginseng may interact with phenelzine sulfate to cause manic episodes and headaches. (SD)
v Hops may cause increased CNS effects when taken concurrently with antidepressants. (LSR)
v Sam-e combined with antidepressants may lead to serotonin syndrome*; do not use concurrently. (LSR) * (See serotonin syndrome below for complete description.)
v St. John’s wort interacts with phenylpiperazine antidepressants such as nefazodone and trazodone (RR) causing serotonin syndrome. * (Serotonin syndrome is a toxic reaction requiring immediate medical attention and is associated with too much serotonin. Symptoms may include anxiety, restlessness, confusion, weakness, tremor, muscle twitching or spasm, high fever, profuse sweating and rapid heart beat.)
v St. John’s wort may cause serotonin syndrome* when used with antidepressants. Do not use concurrently. (LSR) * (See serotonin syndrome above for complete description.)
v St. John’s wort interacts with amitriptyline (and theoretically other tricyclic anti-depressants) causing a worsening of depression. (RR)
Anti-diabetic drugs (Amaryl, Glucophage, Avandia, Orinase)
v Basil may increase the hypoglycemic effects of insulin; do not use concurrently. (LSR)
v Bilberry leaves may significantly decrease blood sugar levels; monitor carefully (Brinter1998). (LSR)
v Chromium may reduce the action of antidiabetics. (LSR)
v Dandelion may increase the effects of insulin; avoid concurrent use. (LSR)
v Ephedra may cause an increase in blood glucose levels; monitor carefully. (LSR)
v Fenugreek may cause acute hypoglycemia in diabetic patients who use insulin or other hypoglycemic drugs.
v Ginseng (American and Asian) interacts with hypoglycemic agents for diabetes causing hypoglycemia and shockbecause the ginsenosides in ginseng lower blood sugar. (RR)
v Glucosamine may theoretically increase the effects of antidiabetics. (LSR)
v Gotu kola may decrease the effectiveness of antidiabetics; do not use concurrently. (LSR)
v Gymnema may possibly increase the action of insulin, other hypoglycemic or oral antidiabetic drugs, leading to hypoglycemic reactions (theoretical). (BG & LSR)
v Horse chestnut may increase the hypoglycemic effects of diabetic medications. (LSR)
v Myrrh taken along with antidiabetics may cause increased hypoglycemic effects; avoid concurrent use. (LSR)
v Siberian ginseng may increase levels of antidiabetic drugs; avoid concurrent use. (LSR)
Anti-diabetic drugs (oral) (Amaryl, Glucophage, Avandia, Orinase)
v Basil may increase the hypoglycemic effects of oral antidiabetics; do not use concurrently. (LSR)
v Bilberry may increase hypoglycemia; use caution if taking concurrently with oral antidiabetics. (LSR)
v Co Q10 It is possible that individuals taking oral hypoglycemics might need to reduce their dosage. (BG)
v Coriander may increase the effects of oral antidiabetic agents; use together cautiously. (LSR)
v Dandelion may increase the effects of insulin; avoid concurrent use. (LSR)
v Ephedra may cause an increase in blood glucose levels if used along with antidiabetic agents; monitor carefully. (LSR)
v Fenugreek may cause acute hypoglycemia in diabetic patients who use insulin or other hypoglycemic drugs. (BG)
v Flaxseed supplementation (as with other high-fiber foods) could potentially require a reduction in hypoglycemic drug dosage. (BG)
v Garlic has hypoglycemic effects; therefore the dosages of oral antidiabetics may need to be adjusted if taken concurrently. (LSR)
v Ginseng is known to decrease blood glucose levels and therefore it may increase the hypoglycemic effect of antidiabetics; avoid concurrent use. (LSR)
v Gotu kola may decrease the effectiveness of antidiabetics; avoid concurrent use. (LSR)
v Gymnema may possibly potentiate the action of insulin or other hypoglycemic drugs, leading to hypoglycemic reactions. (BG)
v Magnesium might increase the effectiveness of oral hypoglycemics in the sulfonylurea family, potentially creating a risk of hypoglycemia. (BG)
v Vitamin E might enhance insulin sensitivity in individuals with type 2 diabetes. This could lead to a risk of hypoglycemia and may warrant adjustment of oral hypoglycemic medications. (BG)
Anti-fungal drugs (itraconazole, Sporanox)
v Goldenseal may slow the metabolism of azole antifungals; avoid concurrent use. (LSR)
v Grapefruit juice causes decreased absorption of itraconazole, which might result in treatment failure. It is thus best to avoid taking grapefruit juice along with itraconazole. (HB)
v Licorice may increase the levels of azole antifungals; avoid concurrent use. (LSR)
Anti-hypertensive drugs (clonidine, Cardura, methyldopa, reserpine, Flomax)
v Black cohosh has weak indications of potential interactions with anti-hypertensive medications. (BG) It may increase the action of antihypertensives; avoid concurrent use. (LSR)
v Coenzyme Q10 can prolong the effects of the antihypertensives enalapril and nitrendipine without increasing their maximum hypotensive effect according to the suggestions of one animal study. (BG)
v Dandelion may increase the effects of antihypertensives; avoid concurrent use. (LSR)
v Goldenseal may worsen high blood pressure. (SDh)
v Hawthorn may interact with or potentiate other cardiovascular drugs and such combinations should be used with caution. (BG)
v Hawthorn may increase hypotension when used with antihypertensives; avoid concurrent use. (LSR)
v Licorice may cause increased hypokalemia if used with antihypertensives; do not use concurrently. (LSR)
v Yohimbe should not be combined with antihypertensive agents. (BG)
Anti-psychotic drugs (phenothiazines) (chlorpromazine, Thorazine, Haldol, lithium, Zyprexa, thioridazine, Mellaril)
v Cranberry Blood levels of antipsychotics can be reduced by excessive use of cranberry juice. (BG)
v Dandelion One case report suggests that individuals on lithium should avoid use of herbs with diuretic properties (such as dandelion) due to risk of dehydration and subsequent lithium toxicity. (BG)
v Ephedra may cause tachycardia in used with phenothiazines; do not use concurrently. (LSR)
v Evening Primrose Oil may cause seizures if used with phenothiazines; do not use concurrently. (LSR)
v Kava Case reports suggest that kava might increase the risk of dystonic reactions in individuals on phenothiazines. (BG)
v Kava may result in neuroleptics movement disorders if taken along with antipsychotics. (LSR)
v Nettle when combined with lithium may result in dehydration, lithium toxicity. (LSR)
v Phenylalanine (D or DL) might increase the risk of developing tardive dyskinesia when combined with antipsychotic drugs. (BG)
v Yohimbe should not be combined with phenothiazines. (BG)
Yohimbe may result in increased toxicity if used with phenothiazines; avoid concurrent use. (LSR)
Anti-retroviral drugs (Indinavir)
v St. John’s wort may interact with Indinavir causing decreased drug effectiveness and worsening of HIV infection by lowering blood levels of the drug. (SD)
Beta-Blockers (metoprolol, Lopressor, propranolol hydrochloride, atenolol)
v Betel Palm (Areca catechu) (pan parag) increases the effects of beta-blockers; do not use concurrently. (LSR)
v Ephedra causes increased hypertension when used with beta-blockers; avoid concurrent use. (LSR)
v Scrophularia ningpoensis (Figwort) may increase the effects of beta-blockers; do not use concurrently. (LSR)
Calcium channel blockers
v Grapefruit juice impairs the breakdown of calcium channel blockers allowing them to build up to potentially dangerous levels in the blood. Avoid grapefruit juice altogether if taking calcium channel blockers. (HB)
v Vitamin D combined with calcium supplements might interfere with calcium channel blockers. (BG)
Congestive heart failure drugs (cardiac glycosides such as Digoxin and Digitoxin,)
v Aloe can cause hypokalemia (lowered blood potassium levels) thereby enhancing the effects of cardiac glycosides. (SD)
v Betel Palm (Areca catechu) (pan parag) increases the effects of cardiac glycosides; do not use concurrently.(LSR)
v Chinese rhubarb used chronically can cause hypokalemia and enhance the effects of cardiac glycosides. (SD)
v The action of figwort may be increased by cardiac glycosides; do not use concurrently. (LSR)
v Ginseng (Siberian) may increase levels of cardiac glycosides; avoid concurrent use. (LSR)
v Hawthorn may interact with or potentiate other cardiovascular drugs and such combinations should be used with caution. (BG)
v Hawthorn may increase the effects of cardiac glycosides; monitor concurrent use carefully. (LSR)
v Licorice can interact with digitalis or other cardiac glycosides causing increased sensitivity. (SD)
v Licorice used along with cardiac glycosides may cause increased toxicity and increased hypokalemia; do not use concurrently. (LSR)
v Ma-huang can interact with cardiac glycosides or halothane to produce cardiac arrhythmia. (SD)
v Ma huang may interact with Digoxin causing irregular heartbeats by overriding the drug’s ability to even out irregular heartbeats. (RR)
v Senna may interact with digoxin causing irregular heartbeats from low blood potassium because long-term use increases the loss of potassium from the stool as a result of laxative effect. (RR)
v St. John’s wort interacts with digoxin-based drugs and can theoretically lead to a worsening of heart failure and irregular heartbeats. (RR)
Corticosteroids (cortisone, prednisone)
v Arginine when used in higher doses may increase the risk of gastric irritation when combined with corticosteroids. (BG)
v Chinese rhubarb used chronically can cause hypokalemia (lowered blood potassium levels) and enhance the effects of corticosteroids. (LSR)
v Licorice can interact with corticosteroids causing salt and water retention, lowered blood potassium, elevated blood pressure, elevated blood sugar and excessive immune suppression by inhibiting an enzyme that breaks down corticosteroids, thus increasing blood levels of the drug. (RR)
v Licorice can interact with corticosteroids to enhance their effects. (SD)
v Licorice may increase the effects of corticosteroids; avoid concurrent use. (LSR)
v Perilla may augment the effect of corticosteroids; avoid concurrent use. (LSR)
v Selenium deficiency may result from treatment with corticosteroids. (BG)
v Senna may interact with corticosteroids causing irregular heartbeats from low blood potassium because long-term use increases the loss of potassium from the stool as a result of laxative effect. (RR)
Decongestants and Antihistamines (phenylpropanolamine, pseudoephedrine, Benadryl, Allegra, Claritin, Phenergan)
v Ephedra may interact with decongestants causing high blood pressure and rapid or irregular heartbeats by magnifying the stimulating effects of these drugs. (RR)
Diuretics
v Licorice can interact with diuretics negating the blood-pressure lowering effect of these drugs and causing irregular heartbeats from increased potassium loss. Licorice mimics the effect of aldosterone, an adrenal hormone that causes sodium retention and potassium loss. (RR)
v Senna may interact with diuretics causing irregular heartbeats from low blood potassium because long-term use increases the loss of potassium from the stool as a result of laxative effect. (RR)o
Thiazide Diuretics such as Diuril.
v Chinese rhubarb used chronically can cause hypokalemia (lowered blood potassium levels) and enhance the effects of thiazide diuretics. (LSR)
v Licorice can interact with thiazide diuretics enhancing their effects. (SD)
v Vitamin D combined with calcium and thiazide diuretics can lead to hypercalcemia. (BG) o
Potassium-sparing Diuretics such as Aldactone, Amiloride, Midamor, triamterene, Enduronv
v Licorice should never be taken along with potassium sparing diuretics. Potassium-sparing diuretics such as Amiloride and Aldactone cause the body to retain potassium whereas licorice has the opposite effect causing the body to lose potassium and thus directly counteracts the effect of these drugs. (HB)
v Licorice may cause increased hypokalemia if used with diuretics (amiloride, triamterene); avoid concurrent use. (LSR)v Use caution supplementing with magnesium if taking amiloride, because amiloride may reduce urinary magnesium excretion. (BG)
v Potassium supplements taken along with potassium-sparing diuretics could raise your potassium levels too high resulting in nausea, vomiting, irritability, diarrhea and changes in heart function. (HB)o
Loop Diuretics such as furosemide (Lasix), bumetanide, ethacrynic acid or torsemide.
v Licorice taken in high dosages or used long-term causes low blood levels of potassium. Loop diuretics also cause potassium loss. Therefore one should avoid taking licorice with loop diuretics. DGL licorice should not affect potassium levels and so should not pose a danger for loop diuretic users. (HB)
Estrogen
v Black cohosh may alter the effects of other hormone replacement therapies; use together cautiously. (LSR)
v Chasteberry (Chaste tree) could conceivably interact with bromocriptine or other drugs intended to affectprolactin levels. For similar reasons, the herb is usually not given along with exogenous estrogen or progesterone or other treatments with endocrine activity. (BG)
v It is theoretically possible that the phytoestrogenic action of hops could have an impact on hormonal therapies such as estrogen. (BG & LSR)
v St. John’s wort may interact with estrogen causing breakthrough bleeding. (RR)
Immunosuppressants (cyclosporine)
v Aloe may conceivably interfere with the action of immune suppressant drugs because of the known immunomodulatory effects of acemannan (a polysaccharide derived from aloe). (BG)
v Astragalus can interact with cyclosporine, azathioprine and methotrexate to impair intended immunosuppressive effects. (SD)
v Curcumin may decrease the effectiveness of immunosuppressants; avoid concurrent use. (LSR)
v Echinacea may decrease the effects of immunosuppressants and should not be used immediately before, during or after transplant surgery. (LSR)
v Eleutherococcus (Siberian Ginseng) Based on its purported immunomodulatory actions it might interfere with the action of immunosuppressive drugs. (BG)
v Ginseng may diminish the effect of immunosuppressants; do not use immediately before, during or after transplant surgery. (LSR)
v Goldenseal might inhibit CYP3A4 (BG) thereby causing a decrease of cyclosporine leading to transplant rejection. (CYP is the abbreviation for cytochrome P450 enzymes. The CYP is usually followed by an Arabic numeral, a letter and another Arabic numeral e.g. CYP 2D6. These enzymes are found in and on the smooth endoplasmic reticulum of liver and other cells and are responsible for a large number of drug biotransformation reactions.)
v Grapefruit juice slows the body’s normal breakdown of cyclosporine, allowing it to build up to potentially excessive levels in the blood. If you take cyclosporine the safest approach is to avoid grapefruit juice altogether. (HB)
v Ipriflavone Based on the observed lymphopenic effects of ipriflavone in which it causes decreased serumlymphocyte levels, it should be used with caution in individuals taking immunosuppressant drugs. (BG)
v Maitake mushroom may decrease the effects of immunosuppressants; do not use immediately before, during or after transplant surgery. (LSR)
v Red yeast rice interacts with cyclosporine increasing the risk of CK elevation and rhabdomyolysis. (Prasad et al 2002) (FA)
v Schisandra may decrease the effectiveness of immunosuppressants; avoid use before, during or after transplant surgery. (LSR)
v St. John’s wort can interact with cyclosporine causing transplant rejection (Ernst 2002) so absolutely avoid taking St. John’s wort with cyclosporine. (RR)
Levodopa (Carbidopa, Sinemet)
v 5-HTP may combine with carbidopa to cause a scleroderma-like condition in which the skin becomes hard and tight (HB & BG)
v Iron may interfere with the absorption of both levodopa and carbidopa by binding to them. You should separate the times you take iron and these drugs by as long as possible. (HB)
v Kava might interfere with the action of dopamine in the body at least partially neutralizing the effects of levodopa. (HB)
v Policosanol might potentiate the action of levodopa, causing increased dyskinesias. (BG)
v Vitamin B6 in higher doses can reduce the therapeutic effects of levodopa. Fortunately, however, since most people with Parkinson’s disease use a combination of levodopa and carbidopa rather than levodopa alone, carbidopa neutralizes the effect of vitamin B6 on levodopa making the interaction with B6 unlikely in practice. (HB)
MAO Inhibitors (Monamine Oxidase Inhibitors) (phenelzine, tranylcypromine)
v Asian Ginseng causes headache, insomnia, trembling and other symptoms when taken along with phenelzine, so it is best to avoid taking these two substances together until more is known. (HB)
v Betel Palm (Areca catechu) (pan parag) increases the effects of MAO inhibitors; do not use concurrently. (LSR)
v Butcher’s Broom may increase the action of MAO inhibitors and precipitate a hypertensive crisis so do not useconcurrently. (LSR)
v Ginkgo may increase the action of MAOIs if taken concurrently (theoretical). (LSR)
v Ginseng use along with MAOIs may result in manic-like syndrome. (LSR)
v Green tea The caffeine in green tea could cause significant interactions with MAO inhibitors. (BG)
v Ma-huang can interact with MAO inhibitors causing hypertension. (SD)
v Ma huang may interact with MAO inhibitors causing extreme high blood pressure by magnifying the stimulating effects of these drugs. (RR)
v Ma huang when combined with MAO inhibitors such as phenelzine (Nardil) may lead to severe tachycardia or hypertension and may be fatal (BG)
Methotrexate
v Echinacea may cause inflammation of the liver if used with methotrexate. (SDh & Miller, 1998)
v Folate (Folic Acid) may safely reduce some of the side effects of methotrexate (particularly elevated liver enzymes) when taken at the same time. (BG)
v Potassium citrate may lead to decreased blood levels and therapeutic effects of methotrexate. Avoid use altogether except under medical supervision. (HB)
v White willow can increase methotrexate blood levels and toxicity. Avoid combining white willow and methotrexate. (HB)
NSAIDs (Aspirin, Anacin, Bufferin, Celebrex, Arthropan, Voltaren, Voltaren SR & XR, Arthrotec, Advil, Motrin, Relafen, Aleve, Daypro, Vioxx, Ibuprofen, salicylic acid)
v Bilberry may increase the action of NSAIDs; use caution if taking concurrently. (LSR)
v Chondroitin used with NSAIDs or salicylates can cause increased bleeding. Do not use concurrently. (LSR)
v Curcumin may result in an increased risk of bleeding if used with anticoagulants or NSAIDs; avoid concurrent use.(LSR)
v Feverfew Because of the effect feverfew has on prostaglandins it suggests that using feverfew and NSAIDs concurrently might increase the risk of gastropathy and nephropathy. (BG)
v Garlic interacts with aspirin causing increased bleeding by inhibiting platelet aggregation. (RR)v
v Gingko interacts with aspirin causing increased risk of bleeding by inhibiting platelet aggregation factor. (RR)
Oral Contraceptives
v Black cohosh may increase the effects of oral contraceptives; avoid concurrent use. (LSR)
v Chasteberry may interfere with the action of oral contraceptives; avoid concurrent use. (LSR)
v Milk Thistle There is one report that silibinin in Milk Thistle can inhibit bacterial beta-glucoronidase activity. Based on this, alterations in clearance of agents such as oral contraceptives whose durations of action depend upon bacterial beta-glucoronidase in the gut might occur. The herb does not appear to affect CYP enzymes at realistic concentrations. (BG)
v St. John’s wort decreases the effectiveness of oral contraceptives and has caused unwanted pregnancies. (BG)
Sedatives/Hypnotics (Ambien [zolpidem], Dalmane, pentobarbital, Nembutal, Phenobarbital, Seconal, Restoril, Halcion, Compoz, Nytol, Sleep-eze, Sominex, Excedrin P.M., Aspirin Free Anacin P.M.)
v 5-HTP may increase the risk of zolpidem-induced visual hallucinations and therefore these two substances should not be taken together. (HB)
v Black cohosh may increase the hypotensive action of sedatives and hypnotics; avoid concurrent use. (LSR)
v Bupleurum can interact with sedatives enhancing their effects. (SD)
v Hops might potentiate the effects ofsedative drugs according to one animal study. (BG)
v Passionflower mightpotentiate sedative medications. (BG)
v St. John’s wort, which is thought to raise serotonin levels, might cause problems if taken along with zolpidem.(HB)
v Valerian may interact with sedatives prolonging sedation by enhancing the effects of these drugs. (RR)
v Valerian may increase the effects of CNS depressants; avoid concurrent use. (LSR)
Selective Serotonin Reuptake Inhibitors (SSRIs) (paroxetine (Paxil), sertraline (Zoloft), fluoxetine (Prozac), citalopram (Celexa), trazodone, Effexor)
v St. John’s wort interacts with SSRIs causing lethargy, tremors, nervousness, restlessness, agitation, nausea and headache by excessively raising serotonin levels in the brain. (RR)
v St. John’s wort may cause serotonin syndrome* when used with SSRIs and trazodone. Do not use concurrently. (LSR) * (Serotonin syndrome is a toxic reaction requiring immediate medical attention and is associated with too much serotonin. Symptoms may include anxiety, restlessness, confusion, weakness, tremor, muscle twitching or spasm, high fever, profuse sweating and rapid heart beat.)
v Yohimbe may cause increased central nervous stimulation if used with SSRIs; do not use together. (LSR)
Statin drugs (Lipitor, Baycol, Zocor, Mevacor [lovastatin])
v Gotu kola may decrease the effectiveness of antilipidemics; avoid concurrent use. (LSR)
v Grapefruit juice reduces the activity of cytochrome P-450 3A4 enzymes, resulting in increased levels of lovastatin.Presumably, because of this effect, consumption of grapefruit juice along with red yeast rice could increase the risk of side effects. (BG)
v Grapefruit juice impairs the body’s normal breakdown of statins allowing them to build up to potentiallyexcessive levels in the blood. If you are taking statins the safest approach is to avoid grapefruit juice altogether. (HB)
v Red yeast rice contains a mixture of statins. Based on the similarity of red yeast rice to statin drugs, the twoshould not be combined without medical supervision. (HB)
Stimulants (caffeine, Excedrin, pseudoephedrine)
v Ephedra may interact with stimulants causing high blood pressure and rapid or irregular heartbeats by magnifying the stimulating effects of these drugs. (RR)
v Yohimbe may cause increased central nervous stimulation if used with CNS stimulants and caffeine; do not usetogether. (BG & LSR)
Sulfaguanidine
v Ginger interacts with sulfaguanidine to enhance absorption. (SD)
Thyroid Hormone (Armour Thyroid, Euthroid, Synthroid)
v Calcium carbonate supplementation interferes with the body’s absorption of thyroid hormone when taken at the same time. To prevent this interaction take thyroid hormone and calcium supplements as far apart as possible (HB)
v Carnitine may inhibit the effects of thyroid hormone replacement therapy; avoid concurrent use. (LSR)
Tranquilizers (alprazolam, diazepam)
v Kava may interact with alprazolam and diazepam interfering with cognitive motor function by enhancing the effects of these drugs. (RR)
v Valerian may interact with alprazolam and diazepam interfering with cognitive motor function by enhancing the effects of these drugs. (RR)
Tricyclic Anti-Depressants (Elavil)
v Ephedra may cause hypertensive crisis when used with tricyclics; do not use concurrently. (LSR)
v St. John’s wort may cause serotonin syndrome* when used with tricyclics. Do not use concurrently. (LSR) *(Serotonin syndrome is a toxic reaction requiring immediate medical attention and is associated with too much serotonin. Symptoms may include anxiety, restlessness, confusion, weakness, tremor, muscle twitching or spasm, high fever, profuse sweating and rapid heart beat.)
v Yohimbe should not be combined with tricyclic antidepressants. (BG)
v Yohimbe may result in increased hypertension if used with tricyclic antidepressants; dose may need to be lowered (Fugh-Berman, 2000) (LSR)
6. INTERACTIONS BY HERB OR SUPPLEMENT
5-HTP
v 5-HTP when combined with carbidopa might increase the risk of a scleroderma-like syndrome in susceptible individuals. (HB & BG)
v Theoretically because SSRIs have been associated with increased hallucinations in individuals taking zolpidem, combining 5-HTP with zolpidem might present a similar risk. (BG)
Acidophilus and other Probiotics None known. (BG)
Aloe
v Aloe can cause hypokalemia (lowered blood potassium levels) thereby enhancing the effects of cardiac glycosides and anti-arrhythmic agents. (SD)
v Aloe may conceivably interfere with the action of immune suppressant drugs because of the knownimmunomodulatory effects of acemannan (a polysaccharide derived from aloe). (BG)
Alfalfa due to its high vitamin K content could, in theory, reduce the effectiveness of anticoagulants; therefore avoid concurrent use. (HB)
Alpha-Lipoic Acid None known. However, based on pharmacological studies it might increase the effects of insulin, although this effect has not been seen in clinical trials. (BG)
Andrographis None known. (BG)
Angelica (Dong quai)
v Angelica interacts with warfarin to cause bleeding (SD)
v Angelica dahurica may delay elimination of tolbutamide (Ishibara, 2000) Avoid concurrent use. (LSR)
v Dong Quai may interact with warfarin (BG) and it may increase the effects of antiplatelets and oral anticoagulants.(LSR)
Arginine
v Arginine when taken in higher doses along with NSAIDs, aspirin, platelet inhibitors, Fosomax, theophylline products, corticosteroids and alcohol may increase the risk of gastric irritation. (BG)
v Arginine when used in higher doses may increase the risk of gastric irritation when combined with corticosteroidsor alcohol. (BG)
v Arginine when taken IV along with ACE inhibitors or potassium sparing diuretics may lead to fatal hypokalemia(theoretical. (LSR)
Artichoke Leaf None known. (BG) However, artichoke tea may interfere with the absorption of iron salts. (LSR)
Astragalus can interact with cyclosporine, azathioprine and methotrexate to impair intended immunosuppressive effects. (SD)
Basil may increase the hypoglycemic effects of insulin and oral antidiabetics; do not use concurrently. (LSR)
Bay leaf may increase the hypoglycemic effects of insulin and oral antidiabetics; do not use concurrently. (LSR)
Berberine (Barberry) (Berberis aquifolium)
v Berberine may increase the antihypertensive action of antihypertensives; use cautiously. (LSR)
v Berberine may increase the effect of calcium channel blockers. (LSR)
Beta-Carotene None known. (BG)
Beta-Sitosterol None known. (BG)
Betel Palm (Areca catechu) (pan parag)
v Betel Palm increases the effects of alcohol, beta-blockers, cardiac glycosides and MAO inhibitors; do not use concurrently. (LSR)
v Betel Palm when combined with neuroleptics can cause extrapyramidal symptoms; do not use concurrently (FughBerman, 2000). (LSR)
v Betel Palm decreases the action of antiglaucoma agents; do not use concurrently. (LSR)
Bilberry
v Bilberry mildly inhibits platelet aggregation and should not be taken along with anticoagulants or antiplatelet agents. (BG)
v Bilberry may increase hypoglycemia; use caution if taking concurrently with insulin or oral antidiabetics. (LSR)v Bilberry may increase the action of NSAIDs; use caution if taking concurrently. (LSR)
Bitter Melon may increase the effect of oral hypoglycemics. (BG)
Black cohosh
v Black cohosh has weak indications of potential interactions with anti-hypertensive medications. (BG) It may increase the action of antihypertensives; avoid concurrent use. (LSR)
v Black cohosh may alter the effects of other hormone replacement therapies; use together cautiously. (LSR)
v Black cohosh may increase the effects of oral contraceptives; avoid concurrent use. (LSR)
v Black cohosh mayincrease the hypotensive action of sedatives and hypnotics; avoid concurrent use. (LSR)
Black pepper should not be taken along with drugs metabolized by cytochrome P-450. (LSR) (Cytochrome P450 enzymes are found in and on the smooth endoplasmic reticulum of liver and other cells and are responsible for a large number of drug biotransformation reactions.)
Blue cohosh None known. (BG)
Borage should not be used with anticonvulsants because they may lower the seizure threshold. [xxvii]
Boron may raise estrogen levels excessively for women taking HRT. (BG)
Boswellia None known. (BG & LSR)
Brewers yeast None known. (BG)
Bromelain There are theoretical concerns regarding using bromelain along with anticoagulants or antiplatelet agents. Bromelain may increase tissue levels of various antibiotics. An animal study showing that bromelain increase pentobarbital sleeping time suggests the potential for interaction with sedatives. (BG)
Bupleurum can interact with sedatives enhancing their effects. (SD)
Burdock
v Burdock if taken with antidiabetics may increase their hypoglycemic effect; avoid concurrent use. (LSR)
v Burdock may possibly increase the hypotensive effect of antihypertensives; avoid concurrent use. (LSR)
v Burdock may possibly increase the hypotensive effect of calcium channel blockers; avoid concurrent use. (LSR)
Butcher’s Broom
v Butcher’s Broom may increase the action of MAO inhibitors and precipitate a hypertensive crisis so do not use concurrently. (LSR)
v Butcher’s Broom may decrease the action of alpha-adrenergic blockers; avoid concurrent use. (LSR)
Butterbur may enhance the effects of anticholinergics, antimigraine agents and beta-blockers; avoid concurrent use. (LSR)
Calcium
v Calcium supplements when combined with high dose vitamin D may affect the action of calcium channel blockers. (BG)
v Calcium supplements may decrease blood levels of atenolol and possibly other beta-blockers. (BG)
v Calcium may interfere with the absorption of antibiotics in the tetracycline and fluoroquinolones families therefore take calcium supplements at last 2 hours after taking these antibiotics. (BG)
v Calcium supplements may interfere with the absorption of levothyroxine. (BG)
v Calcium carbonate supplementation interferes with the body’s absorption of thyroid hormone when taken at the same time. To prevent this interaction take thyroid hormone and calcium supplements as far apart as possible (HB)
Cardamom None known. (LSR)
Carnitine may inhibit the effects of thyroid hormone replacement therapy; avoid concurrent use. (LSR)
Cat’s claw (Una de gato)
v Evidence suggests that cat’s claw might inhibit CYP3A4. (BG) (CYP is the abbreviation for cytochrome P450 enzymes. The CYP is usually followed by an Arabic numeral, a letter and another Arabic numeral e.g. CYP 2D6. These enzymes are found in and on the smooth endoplasmic reticulum of liver and other cells and are responsible for a large number of drug biotransformation reactions.)
v Cat’s claw may increase the hypotensive effects of antihypertensives; avoid concurrent use. (LSR)
v Cat’s claw may interact with insulin; avoid concurrent use. (LSR)
Cayenne may increase absorption of theophylline, possibly leading to toxic levels. (BG)
Chamomile
v Chamomile contains coumarin compounds that might potentiate anticoagulant or antiplatelet agents, although there are no specific reports of such interactions. (BG)
v Chamomile may increase the effects of other sedatives; avoid concurrent use. (LSR)
v A general survey of plant constituents suggests that chamomile might inhibit CYP3A4. (BG) (CYP is the abbreviation for cytochrome P450 enzymes. The CYP is usually followed by an Arabic numeral, a letter and another Arabic numeral e.g. CYP 2D6. These enzymes are found in and on the smooth endoplasmic reticulum of liver and other cells and are responsible for a large number of drug biotransformation reactions.)
Chasteberry (Chaste tree)
v Chasteberry could conceivably interact with bromocriptine or other drugs intended to affect prolactin levels. For similar reasons, the herb is usually not given along with exogenous estrogen or progesterone or other treatments with endocrine activity. (BG)
v Chasteberry may interfere with the action of oral contraceptives; avoid concurrent use. (LSR)
Chinese cucumber: see Trichosanthes kirilowii
Chondroitin sulfate used with anticoagulants, NSAIDs or salicylates can cause increased bleeding; do not use concurrently. (LSR)
Chromium
v Chromium supplementation may be useful for correcting the reduction of HDL levels that can occur in individuals taking beta-blockers. (BG)
v Chromium may reduce the action of antidiabetics. (LSR)
Cinnamon None known. (LSR)
Citrus bioflavonoids (Diosmin/Hesperidin) None known. (BG)
Coenzyme Q10
v It is possible that individuals taking oral hypoglycemics might need to reduce their dosage, although this has not been reported; and one animal study suggests that CoQ10 can prolong the effects of the antihypertensives enalapril and nitrendipine without increasing their maximum hypotensive effect. (BG)
v Coenzyme Q10 may decrease the action of anticoagulants; avoid concurrent use. (LSR)
Colostrum None known (BG)
Copper Oral contraceptives might increase levels of copper in the body and; conversely, AZT might deplete copper stores. (BG)
Cramp Bark (Black Haw) increases the action of anticoagulants; do not use concurrently. (LSR)
Cranberry Blood levels of antidepressants, antipsychotics and morphine-based analgesics can be reduced by excessive use of cranberry juice; and, theoretically some antibiotics could be inhibited by the reduced urinary pH caused by cranberry. (BG)
Creatine Formal drug interaction studies have not been done. (BG)
Curcumin
v There is a potential for drug interactions because curcumin inhibits cytochrome P-450 isozymes. (BG) (Cytochrome P450 enzymes are found in and on the smooth endoplasmic reticulum of liver and other cells and are responsible for a large number of drug biotransformation reactions.)
v Curcumin may result in an increased risk of bleeding if used with anticoagulants or NSAIDs; avoid concurrent use. (LSR)
v Curcumin may decrease the effectiveness of immunosuppressants; avoid concurrent use. (LSR)
Dandelion
v Since dandelion leaf extract contains coumarins it could theoretically interact with anti-coagulants enhancing their effects. (BG)
v One case report suggests that individuals on lithium should avoid use of herbs with diuretic properties (such as dandelion) due to risk of dehydration and subsequent lithium toxicity. (BG)
v Dandelion may increase the effects of insulin and antihypertensives; avoid concurrent use. (LSR)
DHEA Theoretically DHEA could interact with other hormonal treatments. However, no such interaction has been reported at this time. And theoretically DHEA may reduce some side effects of corticosteroid drugs. (BG)
Dioscorea (Wild yam) None known. (LSR)
Dong quai see Angelica
Echinacea
v Echinacea may cause inflammation of the liver if used with methotrexate. (SDh)
v Evidence suggests that Echinacea angustifolia root might inhibit CYP3A4. (BG) (CYP is the abbreviation for cytochrome P450 enzymes. The CYP is usually followed by an Arabic numeral, a letter and another Arabic numeral e.g. CYP 2D6. These enzymes are found in and on the smooth endoplasmic reticulum of liver and other cells and are responsible for a large number of drug biotransformation reactions.)
v Echinacea may decrease the effects of immunosuppressants and should not be used immediately before, during or after transplant surgery. (LSR)
v Echinacea if taken during pregnancy may promote spontaneous abortions. Therefore Echinacea is contra-indicated for pregnant women. (Chow et al 2006) (Barcz et al 2007)
v Echinacea when combined with acetaminophen may result in increased incidences of hepatotoxicity and nephrotoxicity. [xxviii]
Elderberry Flower None known (BG)
Eleutherococcus (Siberian Ginseng)
v None known. However, based on its purported immunomodulatory actions eleutherococcus (Siberian Ginseng) might interfere with the action of immunosuppressive drugs. (BG)
v Eleutherococcus (Siberian Ginseng) may increase levels of antidiabetic drugs and cardiac glycosides; avoid concurrent use. (LSR)
Ephedra (Ma huang)
v Ephedra may interact with stimulants causing high blood pressure and rapid or irregular heartbeats by magnifying the stimulating effects of these drugs. (RR)
v Ephedra may interact with MAO inhibitors causing extreme high blood pressure by magnifying the stimulating effects of these drugs. (RR)
v Ephedra when combined with MAO inhibitors such as phenelzine (Nardil) may lead to severe tachycardia or hypertension and may be fatal (BG)
v Ephedra may interact with decongestants causing high blood pressure and rapid or irregular heartbeats by magnifying the stimulating effects of these drugs. (RR)
v Ephedra can interact with cardiac glycosides or halothane to produce cardiac arrhythmia. (SD)
v Ephedra may interact with Digoxin causing irregular heartbeats by overriding the drug’s ability to even out irregular heartbeats. (RR)
v Ephedra causes increased hypertension when used with beta-blockers; avoid concurrent use. (LSR)
v Ephedra may cause tachycardia in used with phenothiazines; do not use concurrently. (LSR)
v Ephedra may cause hypertensive crisis when used with tricyclics; do not use concurrently. (LSR)
v Ephedra may cause an increase in blood glucose levels if used along with antidiabetic agents; monitor carefully. (LSR)
Evening Primrose Oil
v Evening Primrose Oil may cause seizures if used with phenothiazines; do not use concurrently. (LSR)
v Evening Primrose Oil should not be used with anticonvulsants because they may lower the seizure threshold. [xxix]
Fennel appears to reduce blood levels of ciprofloxacin, possibly impairing its effectiveness. (HB)
Fenugreek
v Fenugreek may cause reduced absorption of all medications used concurrently. (LSR)
v Fenugreek may cause acute hypoglycemia in diabetic patients who use insulin or other hypoglycemic drugs. (BG)
v Fenugreek may increase the risk of bleeding when used concurrently with anticoagulants. (LSR)
Feverfew
v Because of the effect feverfew has on prostaglandins it suggests that using feverfew and NSAIDs concurrently might increase the risk of gastropathy and nephropathy. (BG)
v Feverfew’s antiplatelet activity suggests a potential interaction with anticoagulant and antiplatelet drugs as well as supplements such as garlic, ginkgo, policosanol and high-dose vitamin E. (BG)
Figwort: see Scrophularia nodosa
Fish Oil Although fish oil does not appear to increase the bleeding complications caused by aspirin, interactions with anticoagulants such as warfarin have not been ruled out. (BG)
Flax may cause a decrease in the absorption of all oral medications if taken concurrently. (LSR)
Flaxseed As with other high-fiber foods, flaxseed supplementation could potentially require a reduction in hypoglycemic drug dosage. (BG)
Flaxseed oil None known. (BG)
Folate (Folic Acid)
v Folate (Folic Acid) may increase seizures in individuals with epilepsy and may interfere with phenytoin therapy. (BG)
v Folate (Folic Acid) may safely reduce some of the side effects of methotrexate (particularly elevated liver enzymes) when taken at the same time. (BG)
Fo-ti None known. (LSR)
Gamma-Linolenic Acid (GLA) None known. (BG)
Ganoderma lucidum (Reishi) None known. (BG)
Garlic
v Garlic interacts with aspirin and warfarin causing increased bleeding by inhibiting platelet aggregation. (RR)v Garlic interacts with warfarin to cause bleeding. (SD)
v Garlic has a blood thinning effect and therefore may be dangerous to take along with heparin. (HB)
v Garlic appears to possess anti-thrombotic activity and should be used with caution in patients on anticoagulants. (BG)
v It is conceivable that garlic could interact with ginkgo, policosanol and high-dose vitamin E, which also have anti-coagulant effects. (BG)
v Garlic has hypoglycemic effects; therefore the dosages of insulin or oral antidiabetics may need to be adjusted if taken concurrently. (LSR)
Genistein None known. (BG)
Gentiana may interfere with absorption of iron salts; separate by at least 2 hours. (LSR)
Ginger
v Ginger interacts with sulfaguanidine to enhance absorption. (SD)
v Because of its effects on platelet action, ginger should be used with care in patients using anticoagulants or antiplatelet agents. (BG)
v Ginger may increase absorption of all medications taken orally. (LSR)
Gingko
v Gingko interacts with aspirin and warfarin causing increased risk of bleeding by inhibiting platelet aggregation factor. (RR)
v Gingko has a blood thinning effect and therefore may be dangerous to take along with heparin (HB) and anticoagulants and antiplatelet agents. (LSR)
v Ginkgo is known to inhibit platelet activation factor and for this reason it is advisable to use caution when combining ginkgo with warfarin, heparin, aspirin or any other drugs with anticoagulant or antiplatelet effects. One case report suggests a probable interaction between ginkgo and aspirin. (BG)
v Ginkgo may increase the action of MAOIs if taken concurrently (theoretical). (LSR)
v Ginkgo may decrease the anticonvulsant effect of anticonvulsants; avoid concurrent use. (LSR)
v Ginkgo may interact with acetaminophen to increase the risk of bleeding. [xxx]
v It is conceivable that ginkgo could interact with garlic, phosphatidylserine, policosanol and vitamin E. (BG)
Ginseng
v Ginseng may decrease the action of anticoagulants. (LSR)
v Ginseng (Panax) interacts with warfarin to cause bleeding or to decrease effectiveness. (SD)
v Ginseng may provide an additive anticonvulsant action (theoretical). (LSR)
v Ginseng may diminish the effect of immunosuppressants; do not use immediately before, during or after transplant surgery. (LSR)
v Ginseng use along with MAOIs may result in manic-like syndrome. (LSR)
v Ginseng may interact with phenelzine sulfate to cause manic episodes and headaches. (SD)
v Ginseng (Asian) causes headache, insomnia, trembling and other symptoms when taken along with phenelzine, so it is best to avoid taking these two substances together until more is known. (HB)
v Ginseng is known to decrease blood glucose levels and therefore it may increase the hypoglycemic effect of antidiabetics; avoid concurrent use. (LSR)
v Ginseng (American and Asian) interacts with hypoglycemic agents for diabetes causing hypoglycemia and shock because the ginsenosides in ginseng lower blood sugar. (RR)
v Ginseng (according to one case report) may inhibit CYP3A4. (BG) (CYP is the abbreviation for cytochrome P450 enzymes. The CYP is usually followed by an Arabic numeral, a letter and another Arabic numeral e.g. CYP 2D6. These enzymes are found in and on the smooth endoplasmic reticulum of liver and other cells and are responsible for a large number of drug biotransformation reactions.)
Glucosamine
v The results of one trial suggest that patients on diuretics might need to take higher doses of glucosamine for full effect. (BG)
v Glucosamine may increase the effects of antidiabetics (theoretical). LSR)
Glutamine Theoretically, high doses of glutamine may overwhelm anticonvulsant drugs and pose a risk to individuals with seizure disorders because many of them work by blocking glutamine stimulation in the brain. (BG)
Goldenseal
v Goldenseal might inhibit CYP3A4 thereby causing a decrease of cyclosporine leading to transplant rejection. If you take cyclosporine the safest approach is to avoid grapefruit juice altogether. (BG) (CYP is the abbreviation for cytochrome P450 enzymes. The CYP is usually followed by an Arabic numeral, a letter and another Arabic numeral e.g. CYP 2D6. These enzymes are found in and on the smooth endoplasmic reticulum of liver and other cells and are responsible for a large number of drug biotransformation reactions.)
v Goldenseal may worsen high blood pressure. (SDh)
v Goldenseal may increase the effects of anti-arrhythmic drugs, alcohol, antihypertensives, beta-blockers and central nervous system depressants; do not use concurrently. (LSR)
v Goldenseal may decrease the effects of anticoagulants, and the absorption of vitamin B; do not use concurrently. (LSR)
v Goldenseal may slow the metabolism of azole antifungals, benzodiazepines, calcium channel blockers and statins; avoid concurrent use. (LSR)
Gotu kola may decrease the effectiveness of antidiabetics and antilipidemics; avoid concurrent use. (LSR)
Grapefruit juice
v Grapefruit juice slows the body’s normal breakdown of cyclosporine, allowing it to build up to potentially excessive levels in the blood. If you take cyclosporine the safest approach is to avoid grapefruit juice altogether. (HB)
v Grapefruit juice causes decreased absorption of itraconazole, which might result in treatment failure. It is thus best to avoid taking grapefruit juice along with itraconazole. (HB)
v Grapefruit juice impairs the body’s normal breakdown of statins allowing them to build up to potentially excessive levels in the blood. If you are taking statins the safest approach is to avoid grapefruit juice altogether. (HB)
v Grapefruit juice reduces the activity of cytochrome P-450 3A4 enzymes, resulting in increased levels of lovastatin. Presumably, because of this effect, consumption of grapefruit juice along with red yeast rice could increase the risk of side effects. (BG) (Cytochrome P450 enzymes are found in and on the smooth endoplasmic reticulum of liver and other cells and are responsible for a large number of drug biotransformation reactions.)
v Grapefruit juice slows the body’s normal breakdown of benzodiazepines, allowing them to build up to potentially dangerous levels in the blood. Therefore avoid grapefruit juice altogether if taking benzodiazepines. (LSR)
v Grapefruit juice impairs the breakdown of calcium channel blockers allowing them to build up to potentially dangerous levels in the blood. Avoid grapefruit juice altogether if taking calcium channel blockers. (HB)
Grape Seed Extract see OPCs
Green tea
v Green tea contains vitamin K, and large doses could potentially interfere with the effectiveness of anticoagulants. In addition, the caffeine in green tea could cause significant interactions with MAO inhibitors. (BG)
v Green tea may increase the action of some bronchodilators. (LSR)
Guggul None known. (BG & LSR)
Gymnema may possibly increase the action of insulin, other hypoglycemic or oral antidiabetic drugs, leading to hypoglycemic reactions (theoretical). (BG & LSR)
Hawthorn
v Hawthorn may interact with or potentiate other cardiovascular drugs and such combinations should be used with caution. (BG)
v Hawthorn may increase hypotension when used with antihypertensives; avoid concurrent use. (LSR)
v Hawthorn may increase the effects of cardiac glycosides; monitor concurrent use carefully. (LSR)
v Hawthorn may increase the sedative effects of CNS depressants such as alcohol, barbiturates and psychotropics; avoid concurrent use. (LSR)
Hops
v Hops might potentiate the effects of sedative drugs according to one animal study. (BG)
v Hops It is theoretically possible that the phytoestrogenic action of hops could have an impact on hormonal therapies such as estrogen. (BG & LSR)
v Hops may cause increased CNS effects when taken concurrently with antidepressants, antipsychotics, antihistamines, alcohol and CNS depressants. (LSR)
v Hops may decrease the levels of cytochrome P-450 drugs such as carbamazepine, warfarin and theophylline. (LSR) (Cytochrome P450 enzymes are found in and on the smooth endoplasmic reticulum of liver and other cells and are responsible for a large number of drug biotransformation reactions.)
Horse Chestnut
v Horse chestnut could theoretically interfere with anticoagulants, aspirin and other salicylates because of the coumarins in it. (BG & LSR)
v Horse chestnut may increase the hypoglycemic effects of diabetic medications. (LSR)
Huperzine A None known. (BG)
Inositol (Vitamin B8) None known. (BG)
Ipriflavone
v Ipriflavone may interact with numerous CYP enzymes, including CYP3A, CYP1A2 and CYP2C9. These interactions may lead to increased serum levels of theophylline, caffeine, theobromine, other polycyclic aromatic compounds, tolbutamide, phenytoin and warfarin. (BG) (CYP is the abbreviation for cytochrome P450 enzymes. The CYP is usually followed by an Arabic numeral, a letter and another Arabic numeral e.g. CYP 2D6. These enzymes are found in and on the smooth endoplasmic reticulum of liver and other cells and are responsible for a large number of drug biotransformation reactions.)v Based on the observed lymphopenic effects of ipriflavone in which it causes decreased serum lymphocyte levels, it should be used with caution in individuals taking immunosuppressant drugs. (BG)
Iron
v Iron may interfere with the absorption of both levodopa and carbidopa by binding to them. You should separate the times you take iron and these drugs by as long as possible. (HB)
v Iron supplements can interfere with the absorption of captopril and perhaps other ACE inhibitors. To minimize any potential problems take iron supplements and ACE inhibitors 2 to 3 hours apart. (HB)
v Iron supplements may mutually interfere with the absorption of antibiotics in the tetracycline and quinolone families, levodopa, methyldopa, carbidopa, penicillamine, thyroid hormone, captopril and possible other ACE inhibitors. Separating intake of the iron and drugs by at least 2 hours is likely to forestall any absorption problem. (BG)
Kava
v Kava may interact with alprazolam and diazepam interfering with cognitive motor function by enhancing the effects of these drugs. (RR)
v Case reports suggest that kava might increase the risk of dystonic reactions in individuals on phenothiazines and could additionally counteract the effectiveness of L-dopa. (BG)
v Kava may result in neuroleptic movement disorders if taken along with antipsychotics. (LSR)
v Kava taken with barbiturates may result in increased sedation. (LSR)
v Kava taken with benzodiazepines may result in increased sedation and coma; do not use concurrently (theoretical). (LSR)v High doses of alcohol increased the effects and toxicity of kava in mice. (BG)
v Kava when combined with acetaminophen may result in increased incidences of hepatotoxicity and nephrotoxicity. [xxxi]
Lecithin None known. (LSR)
Lemon Balm may increase the sedative effects of barbiturates and CNS depressants. (LSR)
Lentinan (Shiitake mushroom) None known. (LSR)
Licorice
v Licorice taken in high dosages or used long-term causes low blood levels of potassium. Loop diuretics also cause potassium loss. Therefore one should avoid taking licorice with loop diuretics. DGL licorice should not affect potassium levels and so should not pose a danger for loop diuretic users. (HB)
v Licorice should never be taken along with potassium sparing diuretics. Potassium-sparing diuretics such as Amiloride and Aldactone cause the body to retain potassium whereas licorice has the opposite effect causing the body to lose potassium and thus directly counteracts the effect of these drugs. (HB)
v Licorice can interact with thiazide diuretics enhancing their effects. (SD)
v Licorice may cause increased hypokalemia if used with diuretics; avoid concurrent use. (LSR)
v Licorice can interact with diuretics negating the blood-pressure lowering effect of these drugs and causing irregular heartbeats from increased potassium loss. Licorice mimics the effect of aldosterone, an adrenal hormone that causes sodium retention and potassium loss. (RR)
v Licorice can interact with corticosteroids to enhance their effects; avoid concurrent use. (SD & LSR)
v Licorice can interact with corticosteroids causing salt and water retention, lowered blood potassium, elevated blood pressure, elevated blood sugar and excessive immune suppression by inhibiting an enzyme that breaks down corticosteroids, thus increasing blood levels of the drug. (RR)
v Licorice can interact with digitalis or other cardiac glycosides causing increased sensitivity (SD) increased toxicity and increased hypokalemia; do not use concurrently. (LSR)
v Licorice increases the cardiac effects of anti-arrhythmic drugs and therefore do not use concurrently. (LSR)
v Licorice may cause increased hypokalemia if used with antihypertensives; do not use concurrently. (LSR)
v Licorice. Whole licorice can cause sodium retention and increase blood pressure, thus counteracting the intended effects of ACE inhibitors. DGL (deglycyrrhizinated licorice) is an altered form of the herb that should not cause these problems. (HB)
Lutein None known. (BG)
Lycopene None known. (BG & LSR)
Lysine used in large amounts causes increased aminoglycoside toxicity; avoid concurrent use. (LSR)
Magnesium
v Magnesium can mutually interfere with absorption of antibiotics in the tetracycline and fluoroquinolones families, as well as nitrofurantoin, penicillamine, ACE inhibitors, phenytoin and H2 blockers. To avoid this problem, magnesium should be taken at least 2 hours before or after taking these drugs. (BG)
v Magnesium might increase the effectiveness of oral hypoglycemics in the sulfonylurea family, potentially creating a risk of hypoglycemia. (BG)
v Use caution supplementing with magnesium if taking amiloride, because amiloride may reduce urinary magnesium excretion. (BG)
Ma huang: see Ephedra
Maitake mushroom may decrease the effects of immunosuppressants; do not use immediately before, during or after transplant surgery. (LSR)
Marshmallow may reduce the absorption of oral medications; do not use concurrently. (LSR)
Melatonin
v Melatonin may increase the anxiolytic effects of benzodiazepines; use together cautiously. (LSR)
v Melatonin used with cerebral stimulants may have a synergistic effect and exacerbate insomnia; avoid concurrent use. (LSR)
v Melatonin used with DHEA may decrease cytokine production; avoid concurrent use. (LSR)
v Melatonin used with magnesium or zinc increases inhibition of N-methyl-D-aspartate (NMDA) receptors; avoid concurrent use. (LSR)
v Melatonin increases the blocking properties of succinylcholine; avoid concurrent use. (LSR)
MSM None known. (BG)
Milk thistle (silibinin)
v There is one report that silibinin can inhibit bacterial beta-glucoronidase activity. Based on this, alterations in clearance of agents such as oral contraceptives whose durations of action depend upon bacterial beta-glucoronidase in the gut might occur. The herb does not appear to affect CYP enzymes at realistic concentrations. (BG)
v Milk thistle Test-tube studies suggested that milk thistle may inhibit certain enzymes (cytochrome P450) in the liver that break down some drugs and supplements, which could lead to higher blood levels of these substances and increased side effects. However, this hasn’t happened in more recent clinical studies. [xxxii]
Minor Bupleurum Decoction has been reported to increase the risk of acute pneumonitis associated with use of interferon. [xxxiii]
Myrrh may cause increased hypoglycemic effects when used with antidiabetic agents; avoid concurrent use. (LSR)
N-Acetyl Cysteine (NAC) Although NAC may enhance or maintain the effectiveness of nitrate therapy, it can also increase headaches. (BG)
Neem None known. (BG & LSR)
Nettle
v Nettle (based on animal studies) may interact with hypoglycemic, antihypertensive or sedative medications; however, there are no case reports of interactions. (BG)
v Nettle may lead to increased CNS depression if used with CNS depressants such as alcohol, barbiturates, sedative/hypnotics and antipsychotics. (LSR)
v Nettle when combined with lithium may result in dehydration, lithium toxicity. (LSR)
v Nettle may decrease the effect of anticoagulants; avoid concurrent use. (LSR)
v Nettle may interfere with the absorption of iron salts. (LSR)
OPCs (Grape Seed Extract) might (based on the activity of other flavonoids) potentiate anticoagulant and antiplatelet agents. (BG)
Oxerutins theoretically might potentiate anticoagulants. (BG)
Papain might potentiate anticoagulant and antiplatelet agents. (BG)
Passionflower
v Passionflower might potentiate sedative medications. (BG)
v Passionflower may cause increased sedation when used with CNS depressants; avoid concurrent use (theoretical). (LSR)
v Passionflower may cause increased MAOI activity when used with MAOIs; avoid concurrent use (theoretical). (LSR)
Pau d’Arco
v Pau d’Arco theoretically may interfere with conventional chemotherapeutic agents. (BG)
v Pau d’Arco may result in an increased risk of bleeding if used with anticoagulants; avoid concurrent use (theoretical). (LSR)
PC SPES might be expected to present all the same risks of drug interactions as estrogen, warfarin and indomethacin. (BG)
Pectin decreases absorption of all drugs, vitamins and minerals if taken concurrently. (LSR)
Peppermint None known. (BG)
Perilla may augment the effect of corticosteroids; avoid concurrent use. (LSR)
Phenylalanine (D or DL) might increase the risk of developing tardive dyskinesia when combined with antipsychotic drugs. (BG)
Phosphatidylcholine None known. (BG)
Phosphatidylserine In vitro studies report that fatty acid esters of phosphatidylserine and phosphatidylethanolamine can synergistically stimulate the anticoagulant effect of heparin. (BG)
Policosanol
v Policosanol appears to potentiate the antiplatelet effects of aspirin. For this reason, caution should be exercised when combining policosanol with any antiplatelet or anticoagulant agent. It is also possible that it could potentiate the anticoagulant properties of garlic, ginkgo, and high-dose vitamin E. (BG)
v According to one report, policosanol might potentiate the action of levodopa, causing increased dyskinesias. (BG)
Pomegranate None known. (LSR)
Potassium
v Potassium supplements taken along with potassium-sparing diuretics could raise your potassium levels too high resulting in nausea, vomiting, irritability, diarrhea and changes in heart function. (HB)
v Potassium may interact with ACE inhibitors by causing irregular heart rhythm, muscle weakness, nausea, vomiting, irritability and diarrhea by increasing potassium levels in the blood even higher. (ACE inhibitors cause the body to retain more potassium than usual.) (HB)
v Potassium citrate may lead to decreased blood levels and therapeutic effects of methotrexate. Avoid use altogether except under medical supervision. (HB)
Propolis None known. (LSR)
Progesterone cream A potential exists for CYP enzyme system interactions. (BG) (CYP is the abbreviation for cytochrome P450 enzymes. The CYP is usually followed by an Arabic numeral, a letter and another Arabic numeral e.g. CYP 2D6. These enzymes are found in and on the smooth endoplasmic reticulum of liver and other cells and are responsible for a large number of drug biotransformation reactions.)
Pycnogenol None known. (LSR)
Pygeum None known (BG & LSR)
Quercetin None known, however, because of quercetin’s effects on platelet aggregation, interactions with antiplatelet and anticoagulant drugs could occur. (BG)
Red yeast rice
v Red yeast rice interacts with cyclosporine increasing the risk of CK elevation and rhabdomyolysis. (Prasad et al 2002) (FA)
v Red yeast rice has drug interactions which are presumably similar to those of other statin drugs, therefore it is reasonable to assume that the incidence of myopathy or rhabdomyolysis may increase in patients also receiving cyclosporine, erythromycin, azole antifungals, high doses of niacin and fibric acid derivatives. In addition using warfarin at the same time may increase the risk of bleeding. (BG)
v Grapefruit juice reduces the activity of cytochrome P-450 3A4 enzymes, resulting in increased levels of lovastatin. Presumably, because of this effect, consumption of grapefruit juice along with red yeast rice could increase the risk of side effects. (BG) (Cytochrome P450 enzymes are found in and on the smooth endoplasmic reticulum of liver and other cells and are responsible for a large number of drug biotransformation reactions.)
v Combining red yeast rice with standard statin drugs would not make sense. (BG)
v Red yeast rice contains a mixture of statins. Based on the similarity of red yeast rice to statin drugs, the two should not be combined without medical supervision. (HB)
Rhubarb (Chinese rhubarb)
v Rhubarb (Chinese rhubarb) used chronically can cause hypokalemia (lowered blood potassium levels) and enhance the effects of thiazide diuretics and corticosteroids. (LSR)
v Chinese rhubarb used chronically can cause hypokalemia and enhance the effects of cardiac glycosides (SD) and anti-arrhythmic drugs. (SD & LSR)
Rose hips None known. (LSR)
Salvia interacts with warfarin to cause bleeding. (SD)
SAMe
v SAMe can increase the metabolism of certain drugs by facilitating their conjugation. However, the clinical significance of this observation is unknown. (BG)
v SAMe may lead to serotonin syndrome* if combined with antidepressants; do not use concurrently. (LSR) * (Serotonin syndrome is a toxic reaction requiring immediate medical attention and is associated with too much serotonin. Symptoms may include anxiety, restlessness, confusion, weakness, tremor, muscle twitching or spasm, high fever, profuse sweating and rapid heart beat.)
Saw Palmetto
v Saw Palmetto may increase the anticoagulant effects of anticoagulants, antiplatelets and NSAIDs leading to increased bleeding time; avoid concurrent use. (LSR)
v Saw Palmetto may antagonize hormone therapy; avoid concurrent use (theoretical). (LSR)
v Saw Palmetto may increase or decrease the effect of immunostimulants; avoid concurrent use (theoretical). (LSR)
Schisandra may decrease the effectiveness of immunosuppressants; avoid use before, during or after transplant surgery. (LSR)
Scrophularia nodosa (Figwort)
v Scrophularia nodosa may increase the effects of antiarrhythmics and beta-blockers; do not use concurrently. (LSR)
v The action of figwort may be increased by cardiac glycosides; do not use concurrently. (LSR)
v Scrophularia nodosa is contraindicated in ventricular tachycardia due to its content of cardiac glycosides. (Brinker p. 96)
Scutellaria baicalensis
v Scutellaria baicalensis may increase sedation of CNS depressants; avoid concurrent use. (LSR)
v Scutellaria baicalensis may decrease the effects of immunosuppressants; avoid concurrent use. (LSR)
Selenium deficiency may result from treatment with corticosteroids, proton pump inhibitors and H2 blockers. (BG)
Siberian Ginseng: see Eleutherococcus
Silibinin see Milk thistle
Slippery elm may decrease the absorption of iron salts; separate by 2 hours. (LSR)
Soy isoflavones may impair thyroid function or reduce absorption of thyroid medication. (BG & LSR)
St. John’s wort
v St. John’s wort interacts with SSRIs causing lethargy, tremors, nervousness, restlessness, agitation, nausea and headache by excessively raising serotonin levels in the brain. (RR)
v St. John’s wort, which is thought to raise serotonin levels, might cause problems if taken along with zolpidem. (HB)
v St. John’s wort can interact with cyclosporine causing transplant rejection (Ernst 2002) so absolutely avoid taking St. John’s wort with cyclosporine. (RR & BG)
v St. John’s wort intake increases the expression of intestinal P-glycoprotein and the expression of CYP3A4 in the liver and intestine. The combined up-regulation in intestinal P-glycoprotein and hepatic and intestinal CYP3A4 impairs the absorption and stimulates the metabolism of cyclosporine, leading to subtherapeutic plasma levels. [xxxiv] (CYP is the abbreviation for cytochrome P450 enzymes. The CYP is usually followed by an Arabic numeral, a letter and another Arabic numeral e.g. CYP 2D6. These enzymes are found in and on the smooth endoplasmic reticulum of liver and other cells and are responsible for a large number of drug biotransformation reactions.)
v St. John’s wort has clinically relevant activity by its effect on multiple cytochromes as well as the transport protein p-glycoprotein. (BG)v St. John’s wort may interact with estrogen causing breakthrough bleeding. (RR)
v St. John’s wort interacts with digoxin-based drugs and can theoretically lead to a worsening of heart failure and irregular heartbeats. (RR)
v St. John’s wort may interact with Indinavir causing decreased drug effectiveness and worsening of HIV infection by lowering blood levels of the drug. (SD)
v St. John’s wort interacts with amitriptyline (and theoretically other tricyclic anti-depressants) causing a worsening of depression. (RR)
v St. John’s wort interacts with phenylpiperazine antidepressants such as nefazodone and trazodone causing lethargy, tremors, nervousness, restlessness, agitation, nausea and headache by excessively raising serotonin levels in the brain. (RR)
v St. John’s wort may interact with warfarin causing increased risk of blood clots by lowering blood levels of warfarin. (RR)
v St. John’s wort lowers blood levels of theophylline causing a worsening of asthma symptoms. Therefore you should not combine St. John’s wort and theophylline. (RR & HB)
v St. John’s wort can reduce serum concentrations of protease inhibitors, nonnucleoside reverse transcriptase inhibitors such as nevirapine, cyclosporine, digoxin, warfarin, tricyclic antidepressants, simvastatin and theophylline. (BG)
v St. John’s wort decreases the effectiveness of oral contraceptives and has caused unwanted pregnancies. (BG)
v St. John’s wort is suspected to interact with etoposide, teniposide, mitoxantrone, doxorubicin, clozapine and olanzapine. (BG)
v St. John’s wort may potentiate the effects of photosensitizing agents. (BG)
v St. John’s wort may lead to severe photosensitivity when combined with ACE inhibitors, loop diuretics, thiazide diuretics, NSAIDs oral contraceptives, sulfonamides, sulfonylureas and tetracyclines; avoid concurrent use. (LSR)
v St. John’s wort may cause serotonin syndrome* when used with antidepressants, tricyclics, amphetamines, SSRIs and trazodone. Do not use concurrently. (LSR) * (Serotonin syndrome is a toxic reaction requiring immediate medical attention and is associated with too much serotonin. Symptoms may include anxiety, restlessness, confusion, weakness, tremor, muscle twitching or spasm, high fever, profuse sweating and rapid heart beat.)
v St. John’s wort may increase MAO inhibition; do not use alcohol and St. John’s wort or MAOIs and St. John’s wort. (LSR)
Tea Tree Oil None known. (BG)
Trichosanthes kirilowii (Chinese cucumber) None known. (LSR)
Tylophora indica None known. (BG)
Tyrosine None known. (BG)
Una de gato: see Cat’s claw
Valerian
v Valerian may interact with alprazolam and diazepam interfering with cognitive motor function by enhancing the effects of these drugs. (RR)
v Valerian may interact with sedatives prolonging sedation by enhancing the effects of these drugs. (RR)
v Valerian may enhance the effects of alcohol. (RR)
v Valerian may, according to animal studies, potentiate pentobarbital, hexobarbital and thiopental. (BG)
v Valerian may increase the effects of CNS depressants; avoid concurrent use. (LSR)
Vinpocetine may impair the effectiveness of warfarin. (BG)
Vitamin A might interact with Accutane by increasing each other’s toxicity due to their structural similarities. (HB)
v Vitamin A may increase the anticoagulant effects of warfarin. (BG)
v Pregnant women taking valproic acid may be at increased risk of adverse effects from vitamin A. (BG)
v Vitamin A taken along with isotretinoin might increase vitamin A toxicity. (BG)
Vitamin B3 (Niacin) might increase serum levels of anticonvulsant medications including carbamazepine and primidone, possibly requiring reduction in drug dosage. (BG)
Vitamin B6 (Pyridoxine) in higher doses can reduce the therapeutic effects of levodopa. Fortunately, however, since most people with Parkinson’s disease use a combination of levodopa and carbidopa rather than levodopa alone, carbidopa neutralizes the effect of vitamin B6 on levodopa making the interaction with B6 unlikely in practice. (HB & BG)
Vitamin C
v Vitamin C might reduce the effects of warfarin and heparin according to weak evidence. (BG)v Vitamin C, according to one study, at very high doses (3 g daily) might increase serum levels of acetaminophen. (BG)
Vitamin D
v Vitamin D when combined with calcium supplements might interfere with calcium channel blockers. (BG)
v Vitamin D when combined with calcium and thiazide diuretics can lead to hypercalcemia. (BG)
Vitamin E
v Vitamin E might potentiate anticoagulant or antiplatelet medications based on its anticoagulant properties. (BG)
v Vitamin E could theoretically interact with herbs and supplements that possess anticoagulant or antiplatelet effects such as garlic, policosanol and ginkgo. (BG)
v Vitamin E might enhance insulin sensitivity in individuals with type 2 diabetes. This could lead to a risk of hypoglycemia and may warrant adjustment of oral hypoglycemic medications. (BG)
Vitamin K antagonizes the action of warfarin. (BG)
White willow
v White willow, also known as willow bark, contains a substance that is converted by the body into a salicylate similar to aspirin. Since combining aspirin with heparin increases the risk of abnormal bleeding, it would be advisable not to combine white willow with heparin. (HB)
v White willow may adversely interact with alcohol, anticoagulants, antiplatelet agents, anti-inflammatory agents, sulfonamide drugs, methotrexate, metoclopramide, phenytoin, probenecid, spironolactone and other potassium-sparing diuretics and valproate. (BG)
v White willow can increase methotrexate blood levels and toxicity. Avoid combining white willow and methotrexate. (HB)
Yohimbe
v Yohimbe should not be combined with tricyclic antidepressants, phenothiazines, antihypertensive agents or central nervous system stimulants. (BG)
v Yohimbe may result in increased toxicity if used with alpha-adrenergic blockers; avoid concurrent use. (LSR)
v Yohimbe may cause increased central nervous stimulation if used with SSRIs, CNS stimulants and caffeine; do not use together. (LSR)
v Yohimbe may result in increased hypertension if used with tricyclic antidepressants; dose may need to be lowered (Fugh-Berman, 2000) (LSR)
v Yohimbe may result in increased toxicity if used with phenothiazines; avoid concurrent use. (LSR)
Zinc supplements can interfere with the absorption of tetracyclines, fluoroquinolones and penicillamine. (BG).
7. TOWARDS A BETTER UNDERSTANDING OF HERBS AND DRUGS
Where to find out more about Herb-Drug InteractionsThere are many herbs for which no drug interactions have been documented; and as new drugs are made available there is always the potential for interactions of herbs with these new drugs. Besides contacting your medical doctor or health care provider who has extensive knowledge of herb-drug interactions there are some good web sites where you can go to for accurate and fairly up to date information on herb-drug interactions, herbal safety and efficacy.
For information on herbal safety and quality Steven Foster, the lead editorial adviser of Herbs for Health, recommends several websites including the American Botanical Council website at www.herbalgram.org and the American Herbal Products Association website at www.ahpa.org. [xxxv]
For information and studies on Chinese herbal safety we recommend consulting the website of the Institute of Traditional Medicine at www.itmonline.org/safety.htm. Subhuti Dharmananda has published an excellent article on this website entitled “Checking for Possible Herbs-Drugs Interactions” which we recommend highly.
For information on the latest published reviews and studies on herb-drug interactions we recommend consulting the vast database of Medline athttp://www.ncbi.nlm.nih.gov/PubMed/.
What The Future Looks Like The WHO has published guidelines in order to define basic criteria for evaluating the quality, safety and efficacy of herbal medicines. The WHO has also prepared pharmacopeic monographs on herbal medicines and the basis of guidelines for the assessment of herbal drugs. [xxxvi]
The United States Pharmacopeia plans to fill the information gap by preparing monographs on many popular botanicals that should be useful to both consumers and health professionals. [xxxvii]
8. CHEMICAL COMPONENTS OF HERBS
A. Alkaloids
Examples of herbs that contain alkaloids are coptis, phellodendron, corydalis, Sophora (root), areca seed, Uncaria and lotus seed.
Alkaloids inhibit bacteria, they have sedative actions (except in the cases of ephedrine in ma-huang and caffeine in tea which are stimulants) and they are antispasmodic.
B. Glycosides
1. Flavonoid glycosides
Herbs with flavonoid constituents include eclipta, licorice, pueraria, sanguisorba and scute. Flavonoids act by reducing inflammation, promoting circulation and stopping bleeding.
2. Anthraquinone glycosides
Quinones are found in the salvia, rhubarb, hu-chang and peony. They act to promote microcirculation and reduce inflammation.
3. Saponin glycosidesv
Saponin glycosides are found in ginseng, licorice, dioscorea, jujube, platycodon and bupleurum. They act by tonifying deficiencies, regulating blood sugar and favorably influencing adrenal hormones.
4. Cardioactive glycosides
5. Coumarin glycosidesv
Coumarins are found in angelica, chiang-huo, tu-huo, cnidium fruit and psoralea.
Coumarins relive pain, reduce inflammation and dispel chills.
6. Other Glycosides.
Cyanogenic glycosidesb.
Phenol glycosidesc.
Thioglycoside glycosidesd.
Alkaloid glycosides
C. Essential Oils
D. Organic Acids
E. Tannins
F. Amino Acids
G. Protein and Enzymes
H. Sugars
Sugars include the class of compounds known as polysaccharides, which are found in ganoderma, cordyceps, coriolus, astragalus and lycium. Polysaccharides enhance bone marrow function, promote macrophage activity and have anti-ulcer effects
I. Wax and Lipids
J. Resins
K. Inorganic Components These include such minerals as potassium, calcium, magnesium and iodine.
L. Pigments Aromatic terpenes are found in citrus, menthe, schizonepeta, perilla leaf, cardamom and cyperus. They act by relieving pain, relieving inflammation, and calming digestive system spasms.
a. Chlorophylls
b. Carotenoids
c. Flavinoids
d. Betalains [xxxviii] [xxxix]
Proper Chinese Medicine Herbal Usage
Use caution when applying strong dispersing formulas in persons who suffer from notable yin or blood deficiency.Formulas that invigorate the yang may produce an agitation response in those who suffer from a kidney or liver yin deficiency.
Formulas that tonify the qi and blood may cause tiredness, flatulence, bloating or other negative symptoms in persons who suffer from qi stagnation.
Some very bitter herbs, such as gentiana and coptis, are known to cause nausea and loss of appetite soon after ingestion.
Persons with hypoacidity of the stomach may experience further reduction in stomach acid when consuming calcium-containing materials such as oyster shell.[xl]
REFERENCES
Abebe, W, “Herbal medication: a potential for adverse interactions with analgesic drugs” J Clin Pharm Ther 2002 Dec;27(6):391-401
Awang DV & A Fugh-Berman, “Herbal interactions with cardiovascular drugs” J Cardiovasc Nurs 2002 Jul;16(4):64-70
Barnes, J, “Pharmacovigilance of herbal medicines: a UK perspective.” Drug Saf. 2003;26(12):829-51
Barnes, P.M. & Eve Powell-Griner, “Complementary and Alternative Medicine Use Among Adults: United States, 2002” CDC Advance Data Report /#343, May 27, 2004www.nccam.nih.gov/news/camsurvey.htm
Bensky, Dan & Randall Barolet, Chinese Herbal Medicine Formulas & Strategies, Seattle: Eastland Press, 1990
Bensky, Dan & Andrew Gamble, Chinese Herbal Medicine: Materia Medica, Seattle: Eastland Press, 1986
Boix, John, Cancer & Natural Medicine, Princeton, MN: Oregon Medical Press 1996
Bratman, Steven, MD & Andrea M. Girman, MD MPH, Mosby’s Handbook of Herbs and Supplements and their Therapeutic Uses, St Louis: Mosby, 2003
Brazier NC & MA Levine, “Drug-herb interaction among commonly used conventional medicines: a compendium for health care professionals” Am J Ther 2003 May-Jun;10(3):163-9
Brinker, Francis, N.D. Herb Contraindications & Drug Interactions, Sandy, OR: Eclectic Medical Publications, 2001
Calixto, J.B. “Efficacy, safety, quality control, marketing and regulatory guidelines for herbal medicines (phytotherapeutic agents), Brazilian Journal of Medical and Biological Research, (2000) 33:179-189
Caron, M.F. & C.M. White, “Evaluation of the antihyperlipidemic properties of dietary supplements” Pharmacotherapy 2001 Apr;21(4):281-7
Coon, JT & E Ernst, “Panax ginseng: a systematic review of adverse effects and drug interactions” Drug Saf 2002;25(5):323-44
Cupp, MJ, “Herbal remedies: adverse effects and drug interactions” Am Fam Physician 1999 Mar 1;59(5):1239-45
Dharmananda, Subhuti, Ph.D., “A Bag of Pearls” Portland, OR: Institute for Traditional Medicine, 2002
Dharmananda, Subhuti, Ph.D., “Checking for Possible Herb-Drug Interactions” Portland, OR: Institute for Traditional Medicine, Sept. 2003
Dharmananda, Subhuti, Ph.D., “Controlled Clinical Trials of Chinese Herbal Medicines: A Review” Portland, OR: Institute for Traditional Medicine, Dec.1997
Dharmananda, Subhuti, Ph.D., “Did the Herbs Cause That” Portland, OR: Institute for Traditional Medicine, May 2001
Dharmananda, Subhuti, Ph.D., “Do Herbs, Vitamins and Antioxidants Adversely Affect Cancer Therapies?” Portland, OR: Inst for Traditional Med., Dec. 2002
Dharmananda, Subhuti, Ph.D., “Drugs in Imported Chinese Herb Products” Portland, OR: Institute for Traditional Medicine, Nov. 1996
Dharmananda, Subhuti, Ph.D., “How Clean and Pure are Chinese Herbs?” Portland, OR: Institute for Traditional Medicine, March 2002
Dharmananda, Subhuti, Ph.D., “Responding to Concerns about Herb-Drug Interactions” A Bag of Pearls: 2001 Update, Portland, OR: Inst. for Trad. Med.
Dharmananda, Subhuti, Ph.D., “Safety Issues Affecting Chinese Herbs: (7 articles) “Magnolia alkaloids” (2000); “The Case of Asarum” (Aug. 2000); “The Case of Ma-huang” (Dec. 2000); “The Case of Kava” (March 2002); “The Case of Xanthium” (Dec. 2002); “The Case of Dictamnus and Herbs for Skin Diseases” (April 2003); “Herbs That May Increase Blood Pressure” (Sept. 2003)
Dharmananda, Subhuti, Ph.D., “Safety Issues Affecting Herbs: (3 articles) “Pyrrolizidine Alkaloids” (Nov. 2001); “How Long can Stimulant Laxatives be Used?” (March 2002); “Herbs That May Increase Blood Pressure” (Sept. 2003)
Dharmananda, Subhuti, Ph.D., “The Interactions of Herbs and Drugs” Portland, OR: Institute for Traditional Medicine, Dec. 2000
Dharmananda, Subhuti, Ph.D., “The Methods of Preparation of Herb Formulas: Decoctions, Dried Decoctions, Powders, Pills, Tablets and Tinctures” Portland, OR: Institute for Traditional Medicine, May 1997
Entrez-PubMed website: http://www.ncbi.nlm.nih.gov/PubMed/
Ernst, E, “St. John’s Wort supplements endanger the success of organ transplantation” Arch Surg 2002 Mar; 137(3):316-9
Ernst, E & MH Pittler, “The efficacy and safety of feverfew (Tanacetum parthenium L.): an update of a systematic review” Public Health Nutr 2000 Dec;3(4A):509-14
Fetrow, Charles W., Pharm D. & Juan R. Avila, Pharm D, The Complete Guide to Herbal Medicine, New York: Simon & Schuster, 2000
Fetrow, Charles W., Pharm D. & Juan R. Avila, Pharm D, Professional’s Handbook of Complementary & Alternative Medicines, Philadelphia: Lippincott Williams & Wilkins, 2004
Foster, Steven, “It’s ‘Official’ – If It’s in the USP”, Herbs for Health, July/Aug. 2003: 56-58
Fugh-Berman, A, “Herb-drug interactions” Lancet 2000 Jan 8;355(9198):134-8
Goldman, Peter, MD, “Herbal Medicines Today and the Roots of Modern Pharmacology” Ann Intern Med 2001 Oct.;135(8 Pt 1):594-600
Harkey, MR et al, “Variability in commercial ginseng products: an analysis of 25 preparations” Am J Clin Nutr 2001 Jun;73(6):1101-6
Harkness, Richard, Pharm., FASCP & Steven Bratman, M.D. Drug-Herb Interactions Bible, Prima Publishing, 2000
Harvey, Richard A. and Pamela C. Champe (Editors) Lippincott’s Illustrated Reviews: Pharmacology, Philadelphia: J. B. Lippincott Co., 1992
Henderson, L et al, “St. John’s wort (Hypericum perforatum): drug interactions and clinical outcomes” Br J Clin Pharmacol 2002 Oct;54(4):349-56
Huntley, A & E Ernst, “A systematic review of the safety of black cohosh” Menopause, 2003 Jan-Feb;10(1):58-64
Ioannides, C., “Pharmacokinetic interactions between herbal remedies and medicinal drugs.” Xenobiotica 2002 Jun;32(6):451-78
Izzo AA, “Drug interactions with St. John’s Wort (Hypericum perforatum): a review of the clinical evidence” Int J Clin Pharmacol Ther 2004 Mar;42(3):139-48
Izzo, A.A. and E. Ernst, “Interactions between herbal medicines and prescribed drugs: a systematic review” Drugs, 2001;61(15):2163-75
Lust, John, N.D., D.B.M., The Herb Book, Simi Valley, CA: Benedict Lust Publications, 1974
Maciocia, Giovanni, The Practice of Chinese Medicine, Edinburgh: Churchill Livingstone, 1994
Markowitz JS & CL DeVane, “The emerging recognition of herb-drug interactions with a focus on ST. John’s wort (Hypericum perforatum, Psychopharmacol Bull. 2001 Winter,35(1):53-64
Martin, J. & J. Dusek, “The Baikal skullcap (Scutellaria baicalensis Georgi) – a potential source of new drugs” (Article in Czech) Ceska Slov Farm. 2002 Nov;51(6):277-83
McCullough, Lynda, “Find the best herbal research” Herbs for Health, May/June 2000, p. 12
Miller, LG, “Herbal medicinals: selected clinical considerations focusing on known or potential drug-herb interactions.” Arch Intern Med. 1998 Nov 9;158(20):2200-11
Mindell, Earl, R.Ph, Ph.D., & Virginia Hopkins, Prescription Alternatives, New Canaan, CT: Keats Publ, 1998
Murray, Lori (Sr. Ed.), Physicians’ Desk Reference 58th Edition, Montvale, NJ: Thomson PDR 2004
Naeser, Margaret A, Ph.D., Outline Guide to Chinese Herbal Patent Medicines in Pill Form, Boston: Boston Chinese Medicine, 1992
Nakagawa A et al, “Five cases of drug-induced pneumonitis due to Sho-saiko-to or interferon-alpha or both” Nihon Kyobu Shikkan Gakkai Zasshi. 1995 Dec;33(12):13361-1366
Pierce, Andrea The American Pharmaceutical Association Practical Guide to Natural Medicines, New York: Wm. Morrow & Co., 1999
Rountree, Robert, M.D., “Herb-drug mix” Herbs for Health, Jan/Feb 2001 pp. 26-27
Rountree, Robert, M.D., “Potential Herb-drug Interactions” Herbs for Health, Jan/Feb 2001 pp.40-41
Skidmore-Roth, Linda, Mosby’s Handbook of Herbs & Natural Supplements, 2nd edition, St. Louis: Mosby, Inc., 2004
Sparreboom A et al, “Herbal remedies in the United States: potential adverse interactions with anticancer agents” j Clin Oncol 2004 Jun 15;22(12):2489-503
Spinella, Marcello Ph.D., “The Importance of Pharmacological Synergy in Psychoactive Herbal Medicines” Alternative Medicine Review, Vol. 7, No. 2, 2002 130-137
Smolinske, SC, “Dietary supplement-drug interactions”, J Am Med Women’s Assoc. 1999 Fall;54(4):191-2,195
Stedman’s Medical Dictionary, 27th Edition. Philadelphia: Lippincott Williams & Wilkins, 2000
Stux, G and R. Hammerschlag (Eds.) Clinical Acupuncture: Scientific Basis, Berlin: Springer-Verlag, 2001
Tesch, BJ, “Herbs commonly used by women: an evidence-based review” Dis Mon 2002 Oct;48(10):671-96
Thompson-Coon JS & E Ernst, “Herbs for serum cholesterol reduction: a systematic review” J Fam Pract. 2003 Jun;52(6):468-78
Tierra, Michael, C.A., N.D., The Way of Herbs, New York: Simon & Schuster, 1990
Vuksan, V. et al, “American ginseng (Panax quinquefolius L.) attenuates postprandial glycemia in a time-dependent but not dose-dependent manner in healthy individuals”, Am J Clin Nutr2001;73:753-8
Vuksan, V. et al “American Ginseng Improves Glycemia in Individuals with Normal Glucose Tolerance; Effect of Dose and Time Escalation” J Am Coll Nutr 2000 Nov-Dec;19(6):738-44
Weil, Andrew, M.D., “When Herbs and Drugs Don’t Mix” Self Healing, Premier Issue, 2004: 8
Weil, Andrew, M.D., “Coping with Chemotherapy and Radiation” Self Healing, July 2004: 5
Weil, Andrew, M.D., “Got Milk Thistle?” Self Healing, August 2004: 3
Williamson, E.M., “Drug interactions between herbal and prescription medicines.” Drug Saf 2003;26(15):1075-92
Yance, Donald R, Jr., C.N., M.H., A.H.G., Herbal Medicine, Healing & Cancer, Chicago: Keats Publishing, 1999
Yeh, Gloria et al, “Systematic Review of Herbs and Dietary Supplements for Glycemic Control in Diabetes” Diabetes Care, Vol 26, No 4, Apr 2003 1277-1294
Yeung, Him-che, O.M.D., Ph.D., Handbook of Chinese Herbal Formulas, Rosemead: Institute of Chinese Medicine, 1995
Yeung, Him-che, O.M.D., Ph.D., Handbook of Chinese Herbs, Rosemead: Institute of Chinese Medicine, 1996
Yuan, Chun-Su et al, “Brief Communication: American Ginseng Reduces Warfarin’s Effect in Healthy Patients”, Ann Intern Med 6 July 2004, Vol 141, Issue 1, pages 23-27
TEXT CITATIONS
[i] Skidmore-Roth, Linda, Mosby’s Handbook of Herbs & Natural Supplements, 2nd edition, St. Louis: Mosby, Inc., 2004
[ii] Calixto, J.B. “Efficacy, safety, quality control, marketing and regulatory guidelines for herbal medicines (phytotherapeutic agents), Brazilian Journal of Medical and Biological Research, (2000) 33:179-189
[iii] Smolinske, SC, “Dietary supplement-drug interactions”, J Am Med Women’s Assoc. 1999 Fall;54(4):191-2,195
[iv] Goldman, Peter, MD, “Herbal Medicines Today and the Roots of Modern Pharmacology” Ann Intern Med 2001 Oct.;135(8 Pt 1):594-600
[v] Bensky, Dan & Andrew Gamble, Chinese Herbal Medicine: Materia Medica, Seattle: Eastland Press, 1986
[vi] Bensky, Dan & Andrew Gamble, Chinese Herbal Medicine: Materia Medica, Seattle: Eastland Press, 1986
[vii] Calixto, J.B. “Efficacy, safety, quality control, marketing and regulatory guidelines for herbal medicines (phytotherapeutic agents), Brazilian Journal of Medical and Biological Research, (2000) 33:179-189
[viii] Skidmore-Roth, Linda, Mosby’s Handbook of Herbs & Natural Supplements, 2nd edition, St. Louis: Mosby, Inc., 2004
[ix] Yeh, Gloria Y et al, “Systematic Review of Herbs and Dietary Supplements for Glycemic Control in Diabetes” Diabetes Care, Vol 26, No. 4, April 2003 1277-1294
[x] Stux, G and R. Hammerschlag (Eds.) Clinical Acupuncture: Scientific Basis, Berlin: Springer-Verlag, 2001
[xi] Coon, JT & E Ernst, “Panax ginseng: a systematic review of adverse effects and drug interactions” Drug Saf 2002;25(5):323-44
[xii] Dharmananda, Subhuti, Ph.D., “Checking for Possible Herb-Drug Interactions” Portland, OR: Institute for Traditional Medicine, Sept. 2003
[xiii] Dharmananda, Subhuti, Ph.D., “A Bag of Pearls” Portland, OR: Inst. for Traditional Medicine, 2002: 63-64
[xiv] Weil, Andrew, M.D., “When Herbs and Drugs Don’t Mix” Self Healing, Premier Issue, 2004: 8
[xv] Bratman, Steven, MD & Andrea M. Girman, MD MPH, Mosby’s Handbook of Herbs and Supplements and their Therapeutic Uses, St Louis: Mosby, 2003
[xvi] Fetrow, Charles W., Pharm D. & Juan R. Avila, Pharm D, Professional’s Handbook of Complementary & Alternative Medicines, Philadelphia: Lippincott Williams & Wilkins, 2004
[xvii] Harkness, Richard, Pharm., FASCP & Steven Bratman, M.D. Drug-Herb Interactions Bible, Prima Publishing, 2000
[xviii] Skidmore-Roth, Linda, Mosby’s Handbook of Herbs & Natural Supplements, 2nd edition, St. Louis: Mosby, Inc., 2004
[xix] Rountree, Robert, M.D., “Potential Herb-drug Interactions” Herbs for Health, Jan/Feb 2001: 40-41
[xx] Dharmananda, Subhuti, Ph.D., “Responding to Concerns about Herb-Drug Interactions” A Bag of Pearls: 2001 Update, Portland, OR: Institute for Traditional Medicine
[xxi] Dharmananda, Subhuti, Ph.D., “Checking for Possible Herb-Drug Interactions” Portland, OR: Institute for Traditional Medicine, Sept. 2003
[xxii] Abebe, W, “Herbal medication: a potential for adverse interactions with analgesic drugs” J Clin Pharm Ther 2002 Dec;27(6):391-401
[xxiii] Abebe, W, “Herbal medication: a potential for adverse interactions with analgesic drugs” J Clin Pharm Ther 2002 Dec;27(6):391-401
[xxiv] Abebe, W, “Herbal medication: a potential for adverse interactions with analgesic drugs” J Clin Pharm Ther 2002 Dec;27(6):391-401
[xxv] Miller, LG, “Herbal medicinals: selected clinical considerations focusing on known or potential drug-herb interactions.” Arch Intern Med. 1998 Nov 9;158(20):2200-11
[xxvi] Weil, Andrew, M.D., “Coping with Chemotherapy and Radiation” Self Healing, July 2004: 5
[xxvii] Miller, LG, “Herbal medicinals: selected clinical considerations focusing on known or potential drug-herb interactions.” Arch Intern Med. 1998 Nov 9;158(20):2200-11
[xxviii] Abebe, W, “Herbal medication: a potential for adverse interactions with analgesic drugs” J Clin Pharm Ther 2002 Dec;27(6):391-401
[xxix] Miller, LG, “Herbal medicinals: selected clinical considerations focusing on known or potential drug-herb interactions.” Arch Intern Med. 1998 Nov 9;158(20):2200-11
[xxx] Abebe, W, “Herbal medication: a potential for adverse interactions with analgesic drugs” J Clin Pharm Ther 2002 Dec;27(6):391-401
[xxxi] Abebe, W, “Herbal medication: a potential for adverse interactions with analgesic drugs” J Clin Pharm Ther 2002 Dec;27(6):391-401
[xxxii] Weil, Andrew, M.D., “Got Milk Thistle?” Self Healing, August 2004: 3
[xxxiii] Nakagawa A et al, “Five cases of drug-induced pneumonitis due to Sho-saiko-to or interferon-alpha or both” Nihon Kyobu Shikkan Gakkai Zasshi. 1995 Dec;33(12):13361-1366
[xxxiv] Ioannides, C., “Pharmacokinetic interactions between herbal remedies and medicinal drugs.” Xenobiotica 2002 Jun;32(6):451-78
[xxxv] McCullough, Lynda, “Find the best herbal research” Herbs for Health, May/June 2000: 12
[xxxvi] Calixto, J.B. “Efficacy, safety, quality control, marketing and regulatory guidelines for herbal medicines (phytotherapeutic agents), Brazilian Journal of Medical and Biological Research, (2000) 33:179-189
[xxxvii] Goldman, Peter, MD, “Herbal Medicines Today and the Roots of Modern Pharmacology” Ann Intern Med 2001 Oct.;135(8 Pt 1):594-600
[xxxviii] Yeung, Him-che, O.M.D., Ph.D., Handbook of Chinese Herbs, Rosemead: Institute of Chinese Medicine, 1996: 26-30
[xxxix] Dharmananda, Subhuti, Ph.D., “A Bag of Pearls” Portland, OR: Inst. for Traditional Medicine, 2002: 19
[xl] Dharmananda, Subhuti, Ph.D., “A Bag of Pearls” Portland, OR: Inst. for Traditional Medicine, 2002: 60-61
Disclaimer
The information in this article is being given for educational purposes only and should not be used as a substitute for obtaining the most up-to-date information from your health care provider. It is not intended to replace any treatment you are currently receiving from your health care provider. Readers should not use any of the products discussed in this book without the advice of a medical professional. Readers are advised to check the most current product information provided by the manufacturer of each product to be administered to verify the recommended dose, the method and duration of administration and contraindications. It is the responsibility of the licensed practitioner, relying on experience and knowledge of the patient, to determine dosages and the best treatment for each individual patient. Neither the author nor the publisher is responsible for your specific health needs that may require medical supervision. Nor shall we be liable or responsible for any loss, injury or damage allegedly arising from any information or suggestion in this article.The Food and Drug Administration has not approved the use of any of the natural treatments discussed in this article. This article and the information contained herein on herbs and supplements has not been approved by the Food and Drug Administration. The herbs or supplements discussed in this article are not intended to be used to diagnose or treat any medical condition.
NONE of the herbs or supplements mentioned in this article should be used internally by persons who are pregnant or lactating and should NOT be given to children.
* * *
I want to thank you for this post. This information was very helpful.Please keep up the good work and I look forward to more of your great posts! lidocaine
This article is absolutely awesome and exhaustive. This is an epic accomplishment and you’ve made a tremendous contribution to human health and general well being!
Thank you very much for this informative, concise and comprehensive article about herbs and drugs interactions. This should be posted in every health store to bring awareness of the potency of herbs and its side effects, specially when combined with other supplements or drugs.
This is an amazing compilation of information that everyone who takes pharmaceutical drugs and wants to use herbs and supplements as well should read. Thank you for this.
Great post! Have nice day ! 🙂 oncrt
This has been very helpful; thank you.
It must have taken you a ton of time to publish this. I’ve looked for years at sites but none as huge as this one. Great Job, and thanks!!