Black cohosh, with the Latin name name Cimicifuga racemosa, grows wild in North America. Native Americans used the rootstock, or underground part of the stem, to make teas, tinctures and extracts for medicine. Herbalists use black cohosh to treat symptoms associated with the reproductive cycle. Black cohosh acts against muscle spasms to relieve menstrual cramps and supports hormonal function to improve fertility.
The brain controls the release of hormones to regulate ovulation. Estrogen provides feedback to the brain regarding how much other reproductive hormones to release. Luteinizing hormone and follicle-stimulating hormone act on the ovaries to release eggs. According to Amanda McQuade Crawford in “The Herbal Menopause Book,” phytoestrogens in black cohosh may compete with estrogen at the estrogen receptors for regulating hormones.
Native Americans used black cohosh to promote menstruation, stop muscle cramping and provide pain relief, as well as using black cohosh for heart and lung ailments and pain associated with swollen joints. Taking black cohosh from menstruation to ovulation may increase the release of hormones to assist with ovulation. According to the National Institutes of Health, black cohosh gained popularity in treating menopausal symptoms, including hot flashes and vaginal dryness.
Because black cohosh is frequently taken for menopause symptoms, the majority of scientific research focuses on the effects of black cohosh related to treating menopausal symptoms. The National Center for Complementary and Alternative Medicine reports on the "Black Cohosh Fact Sheet" mixed results from research, and one study showed no difference in results between placebo and black cohosh. One study reported in Alternative Medicine Review compared hormone replacement therapy with black cohosh in 62 post-menopausal women, and results showed black cohosh produced a weak estrogen-like effect.
Under medical supervision, black cohosh, along with other herbs, has been used to induce labor and assist in delivery. Because of the estrogen-like activity, black cohosh should be avoided during early pregnancy to prevent miscarriage.
Black cohosh may cause upset stomach or vomiting. Other common side effects include breast tenderness, weight gain, headaches and lightheadedness. Allergic reactions may produce rash. The “Black Cohosh Fact Sheet” from the National Institutes of Health warns of possible liver inflammation or damage from black cohosh and to seek medical help for abdominal pain or yellowing of the skin or whites of the eyes, though black cohosh has not been implicated as the cause. One Italian case study reported in Phytomedicine showed muscle damage with the use of an over-the-counter formulation of black cohosh for symptoms of menopause.