Herbal Supplements and Their Interactions with Prescription Medications

Herbal supplements have a long history of use dating back to early Chinese medicine. An herb (also called a botanical) is a plant or plant part used for its scent, flavor, and/or therapeutic properties. There are more than 11,000 species of herbal plants for medicinal use and 500 species used in complementary medicine. The most frequently used herbs are ginkgo biloba, ginseng, garlic, glucosamine sulphate, Echinacea, St. John's wort, saw palmetto, and kava. Twelve to thirty-seven percent of U.S. consumers have used herbal supplements for health promotion or treatment of various chronic diseases. An estimated 40% of the older population use or have tried herbal remedies. Unfortunately, one third of current herbal users are at risk of an herb-drug interaction. Drug interactions account for 3% to 5% of preventable in hospital admissions.

It's important to know that herbal supplements do not have to meet the same high standards as medications for proof of safety, effectiveness and quality. Just because an herbal supplement is labeled "natural" does not mean it is safe or without any harmful effects. In 1994, the U.S. Congress passed the Dietary Supplement Health and Education Act (DSHEA) which classified herbal supplements as "dietary supplements" and created a $5.8 billion market. In the U.S., herbals and other dietary supplements are regulated by the U.S. Food and Drug Administration (FDA) as foods, not drugs. Herbal supplements must comply only with the Good Manufacturing Practice (GMP) regulations for foods. So, herbal manufacturers have virtually no regulatory responsibility to ensure safety of their products (not required to conduct premarketing testing for safety or efficacy). Herbal supplements that have pharmacological activity have the potential for adverse side effects and/or toxicity.

Herbal supplements and conventional drug therapy are often taken in combination. So, what's a consumer to do when deciding on herbal supplements? Here are a few tips to consider:

  1. Herbal supplements should never be a substitute for treatment
  2. Consumers and healthcare providers must evaluate the individual evidence for each herbs' beneficial claims or effects
  3. Learn as much as you can about a product before starting any herbal supplement because some herbals can interact with prescription and nonprescription medicines
  4. If you have a blood clotting disorder, diabetes, heart disease, high blood pressure, Parkinson's disease, an enlarged prostate gland, a psychiatric problem, an autoimmune disease or other serious medical conditions, you should avoid taking herbal products unless under the supervision of a physician
  5. Price is not necessarily an indication of the products quality or effectiveness
  6. Look on the label for the words "meets USP standards," which is increasingly seen as a sign that the product has been tested for quality and purity
  7. Herbals and other "natural" medicine should be considered drugs that can cause side effects
  8. Do not use herbal supplements during pregnancy and lactation unless directed by a physician
  9. Do not give herbal supplements to infants or young children
  10. If side effects develop, stop taking the herbal supplement and call a physician

Did you know?

Ginkgo biloba
- taken with a diuretic (water pill) will likely raise blood pressure
- taken with an anti-clotting medicine may increase bleeding tendencies
- may interfere with oral diabetic agents lowering blood sugar levels and increasing heart rates
- may increase bleeding tendencies in menopausal women
St. John's wort
- mixed with anti-depressants, may increase the medications' effects
- interacts with anesthesia, prolonging effect
- may decrease levels of digoxin
- decrease effectiveness of HIV fighting drugs
- taken on a regular basis can:
Increase strength of aspirin
Increase the drug Coumadin (increase bleeding)
- may decrease effectiveness of immunosuppressant agents
- may cause inflammation of the liver if used with certain steroids, methotrexate and others

Be consumer wise when deciding on herbal supplement usage.

The following are reliable sources for further information: