Selective estrogen receptor modulators (SERMs) are a type of medication that can both mimic and block the effects of estrogen in different tissues. They do this by interacting with estrogen receptors in various cells. SERMs are often used to treat conditions related to estrogen, such as osteoporosis, infertility, and some types of breast cancer. Common SERMs include tamoxifen and raloxifene. Raloxifene is commonly used to treat osteoporosis because it can mimic estrogen's beneficial effects on bone density, increasing bone density in the lower spine and hips and reducing the risk of vertebral fractures. Each SERM works differently, so your doctor will help determine which one is best for you. Be sure to understand the potential side effects and discuss them with your doctor before starting new SERM treatment.