Black cohosh is an herb traditionally used to treat menopausal symptoms (hot flashes). It is also known as black snakeroot, bugbane, and rattleweed and is native to North America. The root and underground stem of the plant are used medicinally. Traditional uses include colds, rheumatism, and gynecological disorders, among many others. Black cohosh is classified as a selective modulator of estrogen receptors. However, its mechanism of action in the treatment of hot flashes is unknown.
The American College of Obstetrics and Gynecology states that black cohosh may be helpful in the short-term management of hot flashes in women. A commonly used dose is 40 mg per day. There is no published scientific data on its long-term use. However, studies are underway to evaluate this issue. Common side effects include stomach upset and rash. There have been rare reports of hepatitis and seizures with the use of black cohosh; however, these findings are controversial. Due to its activity on estrogen receptors, black cohosh should not be used by women with a history of or a high risk for breast cancer.