When you hear the term black cohosh, you most likely think of menopause. Indeed, this buttercup-family plant, known as either Actaea racemosa or Cimicifuga racemosa, shows great promise in relieving the many uncomfortable side effects of menopause, making it one of the most well-known herbal remedies even among mainstream health circles.

But black cohosh hasn’t always been so widely celebrated. Until 2002, hormone therapy had been the go-to fix for millions of women seeking relief from hot flashes, night sweats, vaginal dryness and low libido associated with menopause. Many found that taking estrogen or a combo of estrogen and progestin (a synthetic version of progesterone) to make up for the body’s slowed hormone production offered marked relief.

Then hormone therapy suddenly tumbled from grace when researchers abruptly pulled the plug on a Women’s Health Initiative study of 16,000 healthy postmenopausal women because they realized the regimen increased risk of breast cancer, stroke, blood clots and heart disease. These findings made major waves in medical circles and the media, prompting healthcare providers and middle-aged women to seek out alternative therapies for a smooth menopause.

Enter black cohosh. Native Americans had long used the herb, indigenous to the eastern United States and Canada, to relieve menopause symptoms and myriad other health issues, and Germans jumped on it in the mid-20th century for the same purposes. Suddenly, mainstream medical doctors in the United States realized this “alternative” remedy might have some muscle behind it.

Scores of studies have looked into black coshosh’s menopausal benefits, including many conducted in the past decade, following hormone replacement’s fallout. Although research results are somewhat inconsistent, with some suggesting the herb has no or limited effect on menopause symptoms, a huge swath of studies demonstrate its effectiveness. 

For instance, according to a study of 304 women published in the journal Obstetrics and Gynecology in May 2005, black cohosh significantly improved menopause symptoms, most notably hot flashes, compared to placebo, with women in the early stages of the transition seeing the greatest benefit. A meta-analysis published in the January-February 2010 issue of Alternative Therapies in Health and Medicine found that six out of nine trials showed black cohosh worked better than placebo, and seven of the studies suggested that black cohosh relieved symptoms by an average of 26 percent.

As for the research that suggests black cohosh isn’t effective, such as a trial of 300 women published in the Annals of Internal Medicine in December 2006, natural medicine proponents point out several serious study limitations. In fact, in April 2012, the American Botanical Council even decried an entire systematic review of 12 trials published online by the journal Gynecological Endocrinology that found black cohosh wasn’t effective, saying the study groups were too small and parameters too varied to be lumped together and compared.

Exactly how black cohosh may alleviate hot flashes, sweats and lethargy remains murky. Until very recently, experts thought the herb contained phytoestrogens, estrogen-mimicking plant chemicals that act on the body’s hormone receptors to tame symptoms. This theory often precluded breast cancer patients and survivors, as well as women at risk of the disease, from taking black cohosh, since additional estrogen can cause cancer cells to proliferate. However, studies have since turned this notion on its head, finding that the herb does not have estrogenic effects. Instead, experts ascribe its effectiveness to active constituents called triterpene glycosides. Some hypothesize that these compounds spark the brain’s serotonin receptors, which are linked to the hypothalamus, the body’s temperature-control center. Therefore, more and more doctors are saying black cohosh is safe even for women living with or concerned about breast cancer.

Concerns had been raised over the past decade that black cohosh may pose problems for the liver. To investigate, the U.S. Pharmacopeia (USP) conducted a thorough review of 30 black cohosh-related adverse event reports and determined that none of these cases of liver troubles could be directly linked to use of the herb. A meta-analysis published in the journal Menopause in April 2011 further backed black cohosh’s safety: Upon review of five studies of more than 1,100 women, researchers determined that black cohosh has no negative effects on liver function.

Beyond easing menopause symptoms, black cohosh is also thought to help regulate menstrual cycles, soothe breast and uterine pain and even manage arthritis, although far less research has been done for these applications.