Potential Herb-Drug Interactions

While herbs and vitamins are vastly more safe than pharmaceutical drugs, there are some potential adverse reactions from taking both together.  This page will go over some of the more common drugs used and caveats regarding the use of certain herbal and nutritional products at the same time.  Taking these medications with other drugs is frequently contraindicated, and one should request the package insert with one's medication to assure they are not taking two incompatible drugs.

EDITORS NOTE:  Since some vitamins and foods may enhance the effect of a drug, it is important to be CONSISTENT in taking your supplements on a daily basis to reduce the likelihood of adverse reactions and poor control.  We suggest working with your doctor to see if you can adjust medication levels rather than discontinuing supplements which may enhance the drugs' effects, and CONSISTENTLY taking a balanced formula which will not result in imbalances of other nutrients.  (You are much more likely to be deficient in nutrients, rather than in the drug!)

Regarding herbals, while interactions with drugs are rare, St John's Wort, an herb used for mild depression, has recently been found to speed the metabolization of several drugs in the stomach and digestive tract, reducing their effectiveness.  Drugs which have been affected are HIV drugs, anti-rejection drugs, and Coumadin (warfarin), a blood thinner.  One should be cautious when taking it and consult a physician.  Ginkgo biloba, another common herbal, is known to thin blood, and should be taken with caution in those taking blood thinners, as well as aspirin, or medication levels adjusted down.

This page is intended to be a quick reference for possible interactions.  For a more complete and thorough herbal database, we suggest going to HerbMed, a much more comprehensive source of information on virtually every medicinal herb.

Anti-hypertensives  NIACIN, MAGNESIUM and CALCIUM may enhance the effect of anti-hypertensive drugs, causing low blood pressure and lightheadedness.  They should be taken consistently and blood pressure medications adjusted accordingly.  GRAPEFRUIT JUICE may also enhance many drugs' effects by reducing their breakdown.
Anti-inflammatories (NSAIDS) Avoid herbal medicinals with known adverse gastrointestinal effects such as GOSSYPOL, COFFEE ARABICA, COLA, and UVA-URSI. (ESP. AVOID ALCOHOL!)
Using with immunostimulating herbal remedies such as ASTRAGALUS, ECHINACEA, LICORICE ROOT, ALFALFA SPROUTS, and ZINC LOZENGES may offset the immunosuppressive effects.
GRAPEFRUIT JUICE may cause increased cyclosporine levels.  ST. JOHN'S WORT may decrease levels.
Avoid internal consumption of ALOE VERA, which may irritate the large intestine and exert a strong purgative effect, leading to a decrease in serum potassium levels and potentiation of cardiac glycosides)

Avoid herbs with digoxin-like substances, e.g. YELLOW FOXGLOVE, ELEUTHEROCOCCUS SENTICOSUS, and SIBERIAN GINSENG.

Avoid use with Quinine, which may increase digoxin levels.  (Quinine is found in tonic water.)

Avoid use with the herb LICORICE (not usually found in the candy), as its diuretic effect can result in low potassium levels and toxicity.

Avoid taking PSYLLIUM fiber, which decreases digoxin absorption, within two hours of taking medication.

Avoid HAWTHORN BERRY, which can potentiate digoxin action, since it acts synergistically.  (Of course, it may decrease the necessity to take digoxin in the first place.)

Avoid SIBERIAN GINSENG, as it increases digoxin levels or may interfere with digoxin assay.

Avoid herbs with a diuretic effect such as ARTICHOKE, GOLDENSEAL, CELERY SEEDS, and DANDELION.
Hypoglycemic Agents
Avoid BUTCHER'S BROOM, BUCHU, DANDELION, and JUNIPER, which are diuretics which may compromise hypoglycemic effects.

Herbs containing hyper or hypoglycemic components may compromise or enhance hypoglycemic effects.  (CHROMIUM, VANADIUM, MAGNESIUM, GYMNEMA SYLVESTRI, MSM and the herb KARELA may actually improve glucose tolerance, so they may reduce the need for medication.)

     Luminal Sodium
Avoid herbals containing THUJONES and VITAMIN B6, which may lower seizure threshold.

Avoid WORMWOOD, an appetite stimulant, which may potentiate phenobarbital effects.

EVENING PRIMROSE OIL contains GLA, which may lower seizure threshold.

Lithium Avoid BUTCHER'S BROOM, BOCHU, DANDELION and JUNIPER, which are diuretics which may enhance the effect of lithium and cause possible toxicity.
Avoid the Ayurvedic preparation SHANKAPULSHPI, which diminishes anti-epileptic effect.

Avoid PRIMROSE OIL, which may lower seizure threshold.

Thyroid Medication
HORSERADISH may depress thyroid function.  KELP contains iodine, which may result in excess thyroid levels when taken with thyroid replacement medications.
Avoid herbs which decrease platelet aggregation (thin blood), since they may cause hemorrhage.  They include CAYENNE, FEVERFEW, GARLIC, WHITE WILLOW BARK (and ASPIRIN) and St. JOHN'S WORT, and GINKGO BILOBA.  (If you take them regularly, however, perhaps your doctor can reduce your medication dosage.)

Avoid high doses of herbs such as DARK GREEN LEAFY VEGETABLES, ALFALFA,  DONG QUAI, DEVIL'S CLAW, DANSHEN and GREEN TEA, as they may cause decreased anticoagulant activity. 

(If you take these nutrients consistently, medication requirements may be reduced or increased.)

Avoid QUININE, as it may cause increased anticoagulant activity.

Taking high doses of VITAMIN C may result in lessened anticoagulant effect, as will high doses of VITAMIN A and K; and taking over 1000 IU of VITAMIN E or the papaya enzyme PAPAIN may result in increased bleeding.

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