Black cohosh (Actaea racemose) is a woodland herb native to North America. The root is used as medicine and is often used for estrogen-related conditions. In some parts of the body, black cohosh might increase the effects of estrogen. In other parts of the body, black cohosh might decrease the effects of estrogen. Black cohosh should not be thought of as an “herbal estrogen” or a substitute for estrogen. People commonly use black cohosh for symptoms of menopause, premenstrual syndrome (PMS), painful menstruation, weak and brittle bones, and many other conditions, there is no good scientific evidence to support most of these uses. Don’t confuse black cohosh with blue cohosh or white cohosh. These are unrelated plants.