Prolia (denosumab) is a prescription medication for the treatment of osteoporosis in postmenopausal women, men at high risk of fractures, and patients receiving certain cancer treatments that weaken bones. It is a monoclonal antibody that targets RANKL, a protein responsible for activating osteoclasts, the cells that break down bone. By inhibiting RANKL, Prolia slows bone loss, increases bone density, and helps reduce the risk of fractures. It is administered as a subcutaneous injection once every six months.