From the Mayo Clinic at http://www.mayohealth.org/mayo/0003/htm/herbdrug.htm

HERB-DRUG INTERACTIONS

Natural not always safe 03.06.00

It's common to think of herbs as "natural" and, therefore, harmless. However, many herbal remedies can interact with prescription medication. Some herbs become toxic if taken with certain drugs, and fatal herb-drug interactions can occur.

Herbal freedom and popularity

Unlike prescription medicines, herbal products are not regulated by the Food and Drug Administration (FDA). In 1994, Congress passed the Dietary Supplement and Health Education Act (DSHEA), which allows companies to market their herbal products without first demonstrating effectiveness or safety to the FDA. Congress acknowledged that many consumers believe herbs provide health benefits and that they want more freedom in deciding if herbal medicine will help them.

"Herbs are not regulated the same as other dietary supplements," says Donald D. Hensrud, M.D., a consultant in preventive medicine and endocrinology at Mayo Clinic in Rochester, Minn. "This means they can be misidentified, contaminated or contain multiple ingredients. There is no quality control for herbs."

Herbal usage in the United States has increased dramatically since the passage of the DSHEA. In 1997, 60 million Americans spent $3.24 billion on herbs for reasons such as migraines, hypertension, depression, weight loss, and sexual stamina. An estimated 15 million adults are at risk for potential herb-drug interactions.

"Patients electing to use herbal supplements for a serious disease in place of proven therapy are truly taking their lives in their own hands," says Thomas P. Moyer, Ph.D., director of the toxicology laboratory at Mayo Clinic, Rochester. "The growing trend of self-therapy is very concerning."

Herbal remedies - There's no magic

Dangerous duos

Hundreds of herbs have been used to complement or replace conventional medicine. Here are some of the most commonly known herb-drug interactions:

Ginkgo biloba - Studies suggest ginkgo may improve circulation, memory and mental function. Side effects include headache and indigestion.

Drug interactions - Ginkgo contributes to the anticoagulant effect of the following drugs and may cause spontaneous and/or excessive bleeding: Aspirin

Clopidogrel (Plavix)

Dipyridamole (Persantine)

Ticlopodine (Ticlid)

Warfarin (Coumadin)

Alzheimer's - Jury still out on ginkgo

Ginseng - Some people believe ginseng boosts energy, improves sexual performance and reduces stress and the effects of aging. It also has been used to provide relief from menopausal symptoms such as depression.

Drug interactions - Ginseng can cause a number of interactions when used with these drugs:

Warfarin - Can increase the anticoagulant effect and lead to bleeding

Phenelzine (Nardil) - Headache, trembling and manic behavior may occur

Digoxin (Lanoxin) - Monitoring drug response may be difficult

Feverfew, garlic and ginger - Feverfew's most common use is for migraines. Garlic is believed to lower cholesterol and reduce blood clot formation in narrowed arteries. Ginger is used to relieve nausea associated with seasickness, motion sickness and anesthesia. Side effects include nervousness, insomnia and tiredness (feverfew), intestinal problems and upset stomach (garlic) and heartburn (ginger).

Drug interactions - Feverfew, garlic and ginger lead to excessive thinning of the blood when used with warfarin.

Ephedra - Commonly found in many weight-loss medications, ephedra has been used as a stimulant and for treatment of asthma. This herb is considered toxic and requires strict medical supervision if used for more than a week. Excessively high doses of ephedra can lead to asphyxiation and heart failure.

Drug interactions - Considered by the FDA to be a risky supplement when used alone and even more so when combined with other medication, ephedra may cause sedation, heart attack, seizure or death when used with these drugs:

Decongestants (such as Actifed, Dristan, Sinutab, Sudafed)

Stimulants (such as caffeine)

Kava - This herb is a sedative used for treating anxiety. Possible side effects of Kava include gastrointestinal problems, liver problems, allergic skin reaction, and yellow discoloration of skin, hair and nails.

Drug interactions - Kava can produce deep sedation and even coma when used with alprazolam. These drugs should not be taken with kava: Sedatives

Sleeping pills

Antipsychotics

Alcohol

Alprazolam (Xanax), an antidepressant

Drugs to treat Parkinson's disease

Anesthetics used during general anesthesia

Echinacea - Sold as an immunostimulant, echinacea is touted as a treatment of upper respiratory tract infections (URIs) and is being studied as a treatment that shortens the duration of the common cold and influenza. Possible side effects are diarrhea, heartburn, intestinal upset, liver problems and skin rash.

Drug interactions - Because it stimulates the immune system, echinacea may alter the effects of these drugs:

Anabolic steroids

Amiodarone (Cordarone)

Methotrexate (Rheumatrex)

Ketoconazole (Nizoral)

Cyclosporine (Sandimmune)

St. John's wort - This herb is used by many to treat mild-to-moderate depression. Studies indicate it causes fewer side effects than prescription antidepressants. Dizziness, dry mouth, fatigue, digestive problems and sensitivity to light are possible side effects.

Drug interactions - If taken with other photosensitizers (such as tetracyclines) individuals may burn faster when exposed to the sun. Those with fair skin should avoid direct sunlight when taking St. John's wort. Other drugs can interact with this herb, including:

Digoxin

Cyclosporine

Oral contraceptives

Recent studies link the use of St. John's wort with serotonin syndrome (a serious condition involving fever, sweating, dizziness and other symptoms) when taken with sertraline (Zoloft), an antidepressant.

Can St. John's wort relieve depression?

Laxatives can speed up the absorption of an herb or drug, and may substantially increase the effectiveness and potential interactions of an herb-drug combination.

Proceed with caution

According to a Mayo Clinic study, 60 percent of those who take herbal supplements do not tell their health care provider. A doctor's ability to correctly diagnose and treat an illness or disease is limited when he or she is unaware of a patient's use of herbs.

Certain precautions should be taken before using herbs or any nontraditional treatment. Here are some tips for herbal remedy users:

Educate yourself - Before starting to take an herb, learn all you can about it. Check for known side effects, drug and food interactions and potential risks associated with your health history.

Tell your doctor - Always inform your doctor about all medications, herbs and supplements you're taking. Discuss the possibility of herb-drug interactions with him or her before starting to take an herb.

Prepare for surgery - Stop taking herbs at least 2 to 3 weeks before surgery. Tell your anesthesiologist before surgery about the herbs you take.

Stop taking it - If you experience any unusual reactions, stop taking the herb immediately and contact your doctor.