Raloxifene is used to prevent and treat osteoporosis (condition in which the bones become thin and weak and break easily) in postmenopausal (women who have experienced a change of life; end of menstrual periods) women. Raloxifene is also used to decrease the risk of developing invasive breast cancer (breast cancer that has spread outside of the milk ducts or lobules into the surrounding breast tissue) in postmenopausal women who are at high risk of developing this type of cancer or who have osteoporosis. Raloxifene cannot be used to treat invasive breast cancer or to prevent invasive breast cancer from coming back in women who have already had the condition. Raloxifene also cannot be used to decrease the risk of developing noninvasive breast cancer. Raloxifene should not be used in women who have not yet experienced menopause. Raloxifene is in a class of medications called selective estrogen receptor modulators (SERMs). Raloxifene prevents and treats osteoporosis by mimicking the effects of estrogen (a female hormone produced by the body) to increase the density (thickness) of bone. Raloxifene decreases the risk of developing invasive breast cancer by blocking the effects of estrogen on breast tissue. This may stop the development of tumors that need estrogen to grow.