Black Cohosh Efficacy for Reducing Menopausal Symptom Severity Menopause occurs when women transition into late middle age, around the age of 51 years (reviewed by Leach and Moore, 2012). During this transition many women will experience a significant decline in quality of life due to the emergence of menopausal symptoms. This decline can be caused by the natural aging process or a medical procedure, but the symptoms are generally the same regardless of the cause. Menopausal symptoms arise when the ovaries gradually become unresponsive to follicle-stimulating hormone (FSH) and luteinizing hormone (LH), thereby producing less circulating progesterone and estrogen. The symptoms include hot flashes and sweating (vasomotor), vaginal atrophy and dryness, and loss of libido.

Most women (? 85%) can expect the duration of menopausal symptoms to last between 5 months and 10 years, with an average of about 3.5 years (reviewed by Leach and Moore, 2012). Given the duration of these symptoms and the sometimes significant impact on quality of life, there is a need for effective ways to manage symptom severity. Historically, the approach offered by physicians was to compensate for reduced levels of circulating estrogen and progesterone using hormone therapy (reviewed by Borrelli and Ernst, 2008a). Hormone replacement therapy (HRT) was widely used until several randomized clinical trials revealed that the health risks associated with prolonged HRT treatment outweighed the benefits for women experiencing mild to moderate symptoms.

Exogenous estrogen has primarily been used to reduce vasomotor symptoms and urogenital atrophy, but its efficacy is highly variable between women and hot flash episodes (Notelovitz, 2006). Close to 20% and 10% of women experiencing hot flashes due to natural or surgically-induced menopause, respectively, experience estrogen unresponsive hot flashes. In addition, although HRT has been shown to be effective for reducing the severity and frequency of hot flashes for most women, there is no consistent evidence suggesting that a women's quality of life will necessarily improve (Luoto, 2009). Given these limitations and the discovery that HRT significantly increases the risk of breast cancer, total cancer, venous thromboembolism, and stroke (Prentice, Manson, and Rossouw, 2009), it should come as no surprise that HRT is no longer recommended for treating menopausal symptoms for most women.

Since HRT has fallen out of favor there is a need to discover other treatments that can reduce symptom severity. Native Americans have historically relied on black cohosh (Cimicifuga racemosa) to treat menstrual irregularity and some contemporary physicians have been recommending the herb to patients unable or unwilling to risk HRT therapy (reviewed...

Opinions about the pharmacological effects of the herb have changed over the years. Current theory proposes that the herb acts on the central nervous system rather than the ovaries, thereby reducing circulating LH levels and symptom severity. Libido has been reported to improve, probably due to the herbs dopaminergic-2 (D2) receptor antagonist activity and the resulting reduction in prolactin levels. The reduced D2 receptor activity has also been associated with increased osteoblast activity, increased bone mineral density, and decreased bone loss.
This report will examine the evidence supporting the use of black cohosh to treat menopausal symptoms. PubMed, the online portal for the National Library of Medicine, will be used to search for recent publications. Preference will be given to strong study designs, including meta-analyses, systematic reviews, and randomized controlled-studies. The quality of the publication will also be taken into consideration; for example, the Cochrane Database of Systematic Reviews and the Journal of the American Medical Association would be preferred over lesser known publications.

The Evidence

The ethical principle of nonmaleficence, or 'first do no harm,' requires medical professionals to first consider the health risks associated with a treatment approach. Borrelli and Ernst (2008b) used a systematic review of the research literature to examine whether black cohosh can be ingested safely by women experiencing menopause. Randomized controlled studies (RCTs), clinical trials, and case studies were included in the analysis, encompassing 4,232 women. Generally speaking, the herb appears to be fairly benign, with gastrointestinal distress and skin rashes being the most common adverse effects. Black cohosh did not increase the risk for breast or endometrial cancer, or coronary artery disease, in the few studies that examined this question. Instead, a retrospective case-controlled study found evidence that black cohosh may protect against breast cancer in patients using HRT (adjusted odds ratio, 0.39; 95% CI, 0.27-0.82). A large retrospective cohort study of breast cancer patients also revealed protection against recurrence (hazards ratio, 0.83; 95% CI, 0.69-0.99). Black cohosh therefore appears to be relatively benign when ingested and does not have estrogenic effects, although Borrelli and Ernst caution that long-term studies have not been done.

Since black cohosh appears to be safe, at least for relatively short treatment periods (