Black cohosh: state of the science and art

Townsend Letter for Doctors and Patients,  May, 2006  by Tori Hudson

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The medicinal use of black cohosh (Actaea racemosa or Cimicifuga racemosa) has a long herbal tradition in North America and Europe. A member of the buttercup family, black cohosh is native to the eastern part of North America and found as far west as Arkansas. Black cohosh was used by Native Americans for a range of disorders, including menstrual cramps, labor pains, general malaise, malaria, kidney ailments, and rheumatism. Additional uses by early settlers in the US colonies included amenorrhea, bronchitis, fevers, back pains, nervous disorders, yellow fever, and diverse problems of the uterus. The Eclectic physicians of the 1800s used Cimicifuga for similar problems such as rheumatism, influenza, labor pains, headaches, nervous disorders, and even smallpox. The root of black cohosh has been approved by the German Commission E to treat premenstrual syndrome, dysmenorrheal, and a variety of menopausal symptoms, including hot flashes, heart palpitations, nervousness, irritability, vertigo, insomnia, and depression. For the last 50-plus years, numerous clinical trials have been conducted on black cohosh for women's disorders in particular, largely in the area of menopause issues. Much of the research on Cimicifuga racemosa indicating use for menopausal symptoms was conducted in Germany in the 1980s and 1990s. New research in the last several years and new studies in the last two years highlight the role of black cohosh in menopause and make it the single most studied botanical for perimenopause and menopause symptoms.

Up until 2003, there had been five placebo-controlled trials studying black cohosh. (1-5) These studies used different black cohosh preparations and different doses, which has made it difficult to come to some clear conclusion about what form and dose of black cohosh is best to utilize. Some of these studies indicate that black cohosh can reduce some important symptoms associated with perimenopause and menopause. The Stoll study (2) reports a statistically significant reduction in the Kupperman Index and the Hamilton Anxiety scores in women taking black cohosh. The Wuttke study (5) demonstrated a statistically significant reduction in the Menopause Rating Scale in women taking black cohosh and taking black cohosh with conjugated equine estrogens. The Jacobsen study found a decrease in sweats, but not in the frequency and severity of hot flashes in women taking black cohosh. (4) The results of this study was tempered by its use of a lower dose of black cohosh and the fact that a large number of women in the study were taking tamoxifen, known to induce hot flashes. Lehmann-Willenbrock and colleagues (3) found no significant differences in the Kupperman Index scores in women taking black cohosh, compared to women taking hormone therapy.

Four new studies on black cohosh and menopause symptoms, three in 2005 and one in 2006, demonstrated positive results in two studies, mixed results in one, and no effect in one. A randomized, multicenter, double-blind clinical trial compared the efficacy of black cohosh extract with placebo in 304 postmenopausal women. (6) Participants were given 40 mg of a standardized extract or placebo for 12 weeks. Clinical efficacy was measured using the Menopause Rating Scale (MRS). The standardized extract of black cohosh was more effective than placebo (P<.001), but was more pronounced during the early menopause years. Hot flushes were the most significant symptom affected by black cohosh, but atrophic changes and moods also decreased statistically significantly in the black cohosh group compared with the placebo group.

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In a Swiss study, researchers compared the efficacy and safety of the black cohosh root with placebo in women with menopause symptoms. (7) This multicenter, 12-week, clinical trial was conducted in 122 menopausal women with three or more hot flashes a day. Measures included weekly scores of hot flashes, the Kupperman Index, and the Menopause Rating Scale. In the primary analysis using the hot flash scores and the Kupperman Index, black cohosh showed no superiority over placebo. There was also no benefit of black cohosh in the Menopause Rating Scale. However, in a subgroup of patients with a high Kupperman Index (more symptoms), there was a significantly superior benefit of the black cohosh (P<0.018). A decrease of 47% was observed in the black cohosh group vs. 21% in the placebo group.

In the highly anticipated Herbal Alternatives for Menopause (HALT) Study, results were disappointing for black cohosh. (8) This randomized, double-blind, controlled trial set out to test the efficacy of three herbal regimens for menopause symptoms, compared to placebo and compared to hormone therapy. Women were given either 1) black cohosh standardized extract 160 mg daily; or 2) a combination herbal product (black cohosh, alfalfa, chaste tree, dong quai, false unicorn, licorice, oats, pomegranate, Siberian ginseng, boron) four capsules daily; or 3) .625 conjugated equine estrogen + 2.5 mg medroxyprogesterone acetate; or 4) placebo. Participants were 351 women, ages 45-55, who experienced two or more vasomotor symptoms daily. After one year, there was no difference in frequency or intensity of vasomotor symptoms between those in the herb groups and those taking the placebo. At three months, the mean number of night sweats was 12% lower in the black cohosh group and 83% lower with hormone therapy vs. placebo. At three months, the overall Wiklund score was 22% lower, and the mean vasomotory symptoms score was 22% lower with black cohosh vs. placebo. Hormone therapy was 61% and 73% lower than placebo. Black cohosh vs. placebo differences were not seen after six months or 12 months. (The Wiklund Menopause Symptoms Index is an instrument validated to evaluate the most common complaints in peri- and early post-menopausal women: hot flashes, sweats, vaginal dryness, sleep, fatigue, depression, headache, irritability, arthralgia, nervousness, palpitations, and vertigo.)