The phytoestrogens in dong quai work with the body's natural estrogen, optimizing female hormones. This action enhances sexual responsiveness, and has a tonic effect on a whole range of menstrual problems including menopause, painful menses, hot flashes, night sweats and mood swings. Dong quai's other qualities include, liver protection, pain relief, and strong antibacterial actions. Dong quai increases production of white blood cells strengthening the immune system, which may play a role in cancer prevention.