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Black Cohosh
- Black cohosh is an herb sold as a dietary supplement in the United States.
- Black cohosh is used for hot flashes and other menopausal symptoms.
- Although preliminary evidence is encouraging, the currently available data are not sufficient to support a recommendation on the use of black cohosh for menopausal symptoms.
- In 2001, the American College of Obstetricians and Gynecologists stated, primarily on the basis of consensus and expert opinion, that black cohosh may be helpful in the short term (6 months or less) for women with vasomotor symptoms of menopause.
- Although few adverse events have been reported, long-term safety data are not available.
What is black cohosh?
Black cohosh (known as both Actaea racemosa and Cimicifuga racemosa ), a member of the buttercup family, is a perennial plant that is native to North America. Other common names include black snakeroot, bugbane, bugwort, rattleroot, rattletop, rattleweed, and macrotys. Insects avoid it, which accounts for some of these common names.
What are the historical uses of black cohosh?
Black cohosh was used in North American Indian medicine for malaise, gynecological disorders, kidney disorders, malaria, rheumatism, and sore throat [3]. It was also used for colds, cough, constipation, hives, and backache and to induce lactation [4]. In 19th-century America, black cohosh was a home remedy used for rheumatism and fever, as a diuretic, and to bring on menstruation. It was extremely popular among a group of alternative practitioners who called black cohosh "macrotys" and prescribed it for rheumatism, lung conditions, neurological conditions, and conditions that affected women's reproductive organs (including menstrual problems, inflammation of the uterus or ovaries, infertility, threatened miscarriage, and relief of labor pains) [4].
What clinical studies have been done on black cohosh and its effect on menopausal symptoms?
Black cohosh is used primarily for hot flashes and other menopausal symptoms. A number of studies using various designs have been conducted to determine whether black cohosh affects menopausal symptoms [5]. Few were placebo-controlled studies, and most assessed symptoms by using the Kupperman index, a scale that combines measures of hot flashes, insomnia, and depression but not vaginal dryness. Those with the best study designs are described below.
A randomized, double-blind, placebo-controlled trial was done in breast cancer survivors because most of these women experience hot flashes and many use complementary or alternative remedies [6]. The women were over age 18 and had completed breast cancer treatment at least 2 months before the trial; 85 women (69 of whom completed the trial) took one tablet of placebo or 40 mg/day of black cohosh (as 20 mg twice daily) for 2 months to determine the effect on hot flashes, excessive sweating, palpitations, headaches, poor sleep, depression, and irritability [J.S. Jacobson, Columbia University, written communication, 2002]. Fifty-nine subjects were using tamoxifen (an antiestrogen treatment for breast cancer); tamoxifen users were distributed almost equally between the treatment and control groups. The frequency and intensity of hot flashes decreased in both groups, with no statistical difference between the groups; excessive sweating decreased significantly more in the treatment group than the placebo group. Other symptoms improved equally in both groups, and scores on a health and well-being scale did not change significantly in either group.
A 24-week study in 60 women who had undergone hysterectomy but retained at least one ovary compared the effects of 8 mg/day of a black cohosh extract (as four 2-mg tablets daily; isopropanol extract version of Remifemin) with three estrogen regimens: estriol (1 mg/day), conjugated estrogens (1.25 mg/day), and estrogen-progestin therapy (one daily Trisequens tablet containing 2 mg estradiol and 1 mg norethisterone acetate) [7]. In all groups a modified Kupperman index measuring additional physical symptoms was significantly lower at 4, 8, 12, and 24 weeks after treatment began. Black cohosh decreased symptoms similarly to the other treatments, but this study was not placebo controlled.
A randomized, double-blind, placebo-controlled trial in 80 menopausal women compared 8 mg/day of a black cohosh extract (as two 2-mg tablets of Remifemin twice daily) with placebo or conjugated estrogens (0.625 mg/day). At 12 weeks, scores on the Kupperman index and the Hamilton anxiety scale were significantly lower in the treated groups than in the placebo group; the scores of participants using black cohosh were somewhat better than the scores of those receiving the estrogen treatment. This is one of the few studies in which hot flashes were scored separately from other symptoms. Daily hot flashes decreased from 4.9 to 0.7 in the black cohosh group, 5.2 to 3.2 in the estrogen group, and 5.1 to 3.1 in the placebo group.
A randomized, 12-week study of 55 menopausal women compared an ethanolic extract of black cohosh (40 drops twice daily) with conjugated estrogens (0.6 mg/day) or diazepam (2 mg/day). Regardless of the treatment, all symptoms improved as measured by the Kupperman index, a depression scale, and an anxiety scale. However, this was not a blinded, placebo-controlled trial and diazepam is not a usual treatment for menopausal symptoms.
Although some study results suggest that black cohosh may help relieve menopausal symptoms, other study results do not. Studies of black cohosh have yielded conflicting data, in part because of lack of rigor in study design and short study duration (6 months or less). In addition, interpretation of these studies is complicated by the fact that different amounts of black cohosh from different sources were used in the various studies and their outcome measures were different. To provide more definitive evidence on the effects of black cohosh on menopausal symptoms, NCCAM is funding a 12-month, randomized, placebo-controlled study to determine whether treatment with black cohosh is effective in reducing the frequency and intensity of menopausal hot flashes. The study will also assess whether black cohosh reduces the frequency of other menopausal symptoms and improves quality of life.
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