The in vitro estrogenic activity of the crude drugs found in Japanese herbal medicines prescribed for menopausal syndrome was enhanced by combining them

Background Japanese herbal medicines can be used as alternatives to estrogen therapy and are sometimes prescribed for menopausal syndrome because they have fewer side effects and are associated with better compliance than estrogen therapy, but little is known about the pharmacological mechanisms of such treatments. This study aimed to explore the mechanisms responsible for the estrogen-like effects of five widely prescribed Japanese herbal medicines (unkeito, kamishoyosan, nyoshinsan, keishibukuryogan, and tokishakuyakusan).