Black Cohosh Evidence Inconclusive

Lara C. Pullen, PhD

September 17, 2012

September 17, 2012 — Although there is currently insufficient evidence to support the use of black cohosh for menopausal symptoms, the data do support the need for additional research, according to a new review by Matthew J. Leach, PhD, from the School of Nursing & Midwifery, University of South Australia, and Vivienne Moore, from the Department of Public Health, University of South Australia, North Terrace, Adelaide. Future trials with black cohosh should focus on important outcomes such as quality of life, bone health, and night sweats.

The review was published online September 12 in the Cochrane Database of Systematic Reviews and included 16 randomized controlled trials with a total of 2027 perimenopausal and menopausal women. No foreign language limits were placed on the review.

The new review represents the most comprehensive systematic review investigating the effects of black cohosh for menopausal symptoms. Although the compiled evidence did not support the use of black cohosh, it also did not refute it.

The doses of black cohosh in the reviewed studies ranged from 8 to 160 mg/day. The mean daily dose was 40 mg, and the mean duration of treatment was 23.4 weeks. The reviewers note that most of the studies did an inadequate job reporting study methods.

With regard to hot flushes, there was no significant difference between black cohosh and placebo (mean difference, 0.07 flushes/day; 95% confidence interval [CI], −0.43 to 0.56 flushes/day; P = 0.79).

In contrast, when compared with black cohosh, hormone therapy significantly reduced daily hot flush frequency and menopausal symptom scores (standardized mean difference, −0.32; 95% CI, 0.13 - 0.51; P = .0009).

Although most of the trials assessed the effect of black cohosh on vasomotor symptoms, the outcomes measured were diverse and not suitable for pooling. Thus, any combined findings should be interpreted with caution.

The studies also used many different standardized menopausal symptom scores/scales/indices. Most of the studies, however, examined the frequency and intensity of vasomotor symptoms, vulvovaginal symptoms, and sexuality.

It was also difficult to form conclusions about the safety of black cohosh because of poor reporting of adverse events, according to the review. Ten of the trials reported adverse events including breast pain/enlargement, infection, and vaginal bleeding/spotting. The reviewers emphasize that future studies of black cohosh should include detailed information on participant withdrawal.

None of the trials reported cost-effectiveness data.

The authors have disclosed no relevant financial relationships.

Cochrane Database Syst Rev. Published online September 12, 2012. Abstract