evista is a prescription medication used totreat or prevent osteoporosis in postmenopausal women. it is also used to reduce the riskof invasive breast cancer in postmenopausal women who have osteoporosis or who are atrisk of invasive breast cancer. evista belongs to a group of drugs called selective estrogenreceptor modulators (serms). it works by mimicking the effects of estrogen to increase the densityof bone. this medication comes in tablet form.it is taken once a day with or without food. common side effects of evista include hotflashes, leg cramps, swelling, and flu-like symptoms.