Black cohosh is a famous Native American gynecological herb, used chiefly to alleviate premenstrual tension and alleviate hot flashes associated with menopause. In clinical trials, black cohosh outperformed both estrogen and placebos in reducing hot flashes from 4.9 to 0.7 per day compared to 3.2 and 3.1 in the estrogen and placebo groups. The most common use is as an alternative to hormone replacement therapy.