CONJUGATED ESTROGENS (Premarin) is used for treating certain symptoms of menopause (eg, hot flashes, vaginal dryness or itching). It is used to prevent osteoporosis (weak bones) after menopause in certain patients. It is used in certain patients to treat low estrogen levels, breast cancer or prostate cancer. Premarin is a mixture of female estrogen hormones. It works by replacing natural estrogens in a woman who can no longer produce enough estrogen. It works for advanced prostate cancer by antagonizing male hormones.