Few herbal interactions are documented
Here are examples of better-known problems
When it comes to potential side affects and drug interactions of alternative medicines, much remains unknown. However, there are a few well-documented exceptions. An informal survey of botanical manufacturers, associations such as the American Botanical Council, and an Internet search of the consumer media yielded the following list of cautions:
1. Flax seed can delay the absorption of common synthetic medicines.
2. Ginseng, either the Asian or Siberian variety, should not be taken by people with high blood pressure.
3. Cascara sagrada, an herbal laxative, is secreted in breast milk and should not be taken by women who are lactating.
4. Garlic, taken as an herbal for circulation improvement, can increase the effect of anticoagulants like warfarin.
5. Echinacea should not be taken by anyone allergic to daisies.
6. Chaparral, in tea and pill form as an alleged anti-cancer herbal, can bring on hepatitis or related liver damage.
7. Teas that contain herbal blends of senna, aloe, rhubarb root, buckthorn, or cascara have been linked to the disruption of potassium levels when taken in large amounts.
8. Pennyroyal, a mint, can induce abortion in some cases.
9. Combining licorice root and laxatives can also disrupt potassium levels.
10. High doses of vitamin A, up to 25,000 International Units a day, may cause liver damage or birth defects.
11. Overdoses of vitamin D, at about 10 times the daily 10 micrograms recommended over long periods, can lead to kidney damage.
12. Overdoses of selenium, from just 5 to 50 milligrams a day, has been blamed for nerve damage.
Faced with these types of examples, botanical proponents agree that interactions are an issue but claim that they are no more troubling than the problems between the over-the-counter or prescription drugs coming to market every day. "Interactions with synthetic drugs is a valid fear," says Michael Murray, a Bothell, WA-based botanical consultant, "but if you get up to speed on the herbs, it's not. So far, we've found no adverse interactions with saw [palmetto] or ginkgo.
"Many of the products have had extensive post-market studies and have found no interactions for many of them, but some natural products do have interaction problems," Murray explains.
Rob McCaleb, president of the Herb Research Foundation in Boulder, CO, adds, "Hospital pharmacists probably know better than anyone how few drug-drug interactions are researched, usually one or two at most. The research simply doesn't exist, and we're talking about drugs they deal with every day.
"On drug-herb interactions, I'd say there are few cases to worry about, but there will be surprises. No one thought you couldn't drink grapefruit juice," he says, referring to a recent FDA warning that the allergy antihistamine Hismanal should not be taken with the juice, as well as with a lengthy list of antibiotics, antidepressants, and AIDS drugs.
[For more information, contact: Rob McCaleb, president, Herb Research Foundation, 1007 Pearl St., Boulder, CO 80302. (303) 449-2265. Greg Ris, USA VP, Indena, 1001 Fourth Ave. Plaza, Seattle, WA 98154. (206) 340-6140. Michael Murray, Professor of Botanics, Bastyr University, Bothell, WA. (425) 747-1976. Kristin Battista, Dietary Supplement Safety and Science Coalition, 410 1st St. SE, Washington, DC 20003. (202) 484-2776. Nancy Jordan, PharmD, BCPS, Holyoke Hospital, 575 Beech St., Holyoke, MA 01040. (413) 534-2549.]
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