Background: Menopause can be a distressing and disruptive time for many women, with many experiencing hot flushes, night sweats, vaginal atrophy and dryness. Postmenopausal women are also at increased risk of osteoporosis. Interventions that decrease the severity and frequency of these menopausal symptoms are likely to improve a woman's well-being and quality of life. Hormone therapy has been shown to be effective in controlling the symptoms of menopause; however, many potentially serious adverse effects have been associated with this treatment. Evidence from experimental studies suggests that black cohosh may be a biologically plausible alternative treatment for menopause; even so, findings from studies investigating the clinical effectiveness of black cohosh have, to date, been inconsistent.
Objectives: To evaluate the clinical effectiveness and safety of black cohosh (Cimicifuga racemosa or Actaea racemosa) for treating menopausal symptoms in perimenopausal and postmenopausal women.
Search methods: Relevant studies were identified through AARP Ageline, AMED, AMI, BioMed Central gateway, CAM on PubMed, CINAHL, CENTRAL, EMBASE, Health Source Nursing/Academic edition, International Pharmaceutical Abstracts, MEDLINE, Natural medicines comprehensive database, PsycINFO, TRIP database, clinical trial registers and the reference lists of included trials; up to March 2012. Content experts and manufacturers of black cohosh extracts were also contacted.
Selection criteria: All randomised controlled trials comparing orally administered monopreparations of black cohosh to placebo or active medication in perimenopausal and postmenopausal women.
Data collection and analysis: Two review authors independently selected trials, extracted data and completed the 'Risk of bias' assessment. Study authors were contacted for missing information.
Main results: Sixteen randomised controlled trials, recruiting a total of 2027 perimenopausal or postmenopausal women, were identified. All studies used oral monopreparations of black cohosh at a median daily dose of 40 mg, for a mean duration of 23 weeks. Comparator interventions included placebo, hormone therapy, red clover and fluoxetine. Reported outcomes included vasomotor symptoms, vulvovaginal symptoms, menopausal symptom scores and adverse effects. There was no significant difference between black cohosh and placebo in the frequency of hot flushes (mean difference (MD) 0.07 flushes per day; 95% confidence interval (CI) -0.43 to 0.56 flushes per day; P=0.79; 393 women; three trials; moderate heterogeneity: I(2) = 47%) or in menopausal symptom scores (standardised mean difference (SMD) -0.10; 95% CI -0.32 to 0.11; P = 0.34; 357 women; four trials; low heterogeneity: I(2) = 21%). Compared to black cohosh, hormone therapy significantly reduced daily hot flush frequency (three trials; data not pooled) and menopausal symptom scores (SMD 0.32; 95% CI 0.13 to 0.51; P=0.0009; 468 women; five trials; substantial heterogeneity: I(2) = 69%). These findings should be interpreted with caution given the heterogeneity between studies. Comparisons of the effectiveness of black cohosh and other interventions were either inconclusive (because of considerable heterogeneity or an insufficient number of studies) or not statistically significant. Similarly, evidence on the safety of black cohosh was inconclusive, owing to poor reporting. There were insufficient data to pool results for health-related quality of life, sexuality, bone health, vulvovaginal atrophic symptoms and night sweats. No trials reported cost-effectiveness data. The quality of included trials was generally unclear, owing to inadequate reporting.
Authors' conclusions: There is currently insufficient evidence to support the use of black cohosh for menopausal symptoms. However, there is adequate justification for conducting further studies in this area. The uncertain quality of identified trials highlights the need for improved reporting of study methods, particularly with regards to allocation concealment and the handling of incomplete outcome data. The effect of black cohosh on other important outcomes, such as health-related quality of life, sexuality, bone health, night sweats and cost-effectiveness also warrants further investigation.