Objective: To review the evidence of herbs commonly used by women.
Data sources: Articles were located by searching Medline, Cochrane Database of Systemic Reviews, and the Combined Health Information Database and by hand searching the reference lists of recent systematic reviews. The databases were searched in January 2000 and October 2000 by using the Latin and common name of each herb.
Methods of study selection: Preference was given to randomized, placebo-controlled trials. When available, English language studies were reviewed. If not, data are presented from review articles that summarize the foreign study.
Results: Many women use herbal therapies. In the United States, herbs are considered dietary supplements. The Food and Drug Administration (FDA) cannot remove them from the market unless they are proven unsafe. The herb industry plans to improve monitoring. Many prospective randomized controlled trials are being funded. Gingko biloba seems to slow the progression of dementia but increases the risk of bleeding. St John's Wort is efficacious for treating mild to moderate depression but has many drug interactions. Ginseng seems to improve well being in perimenopausal women, but it is often impure and has side effects and drug interactions. Garlic slightly lowers blood pressure and lipids. Echinacea slightly decreases the duration of colds but does not prevent them. Valerian is beneficial for insomnia, but there is no long-term safety data. Black cohosh may help the symptoms of perimenopause, and chasteberry may improve premenstrual syndrome. More study is needed on both herbs.
Conclusion: Some herbs are medically useful, but the American public would benefit from increased regulation. Manufacturers should be able to ensure that herbs contain pure ingredients. Side effects and drug interactions should be listed. Well-designed studies are being conducted. The results will be helpful to physicians and patients when the clinical evidence becomes available.