Teriparatide injection is used to treat osteoporosis (a condition in which the bones become thin and weak and break easily) in women who have undergone menopause ('change in life,' end of menstrual periods), who are at high risk of fractures (broken bones), and cannot use other osteoporosis treatments. It is also used to increase bone mass in men with certain types of osteoporosis who are at high risk for having broken bones (fractures), and who cannot use other osteoporosis treatments. Teriparatide injection is also used to treat osteoporosis in men and women who are taking corticosteroids (a type of medication that may cause osteoporosis in some patients) who are at high risk of fractures (broken bones), and cannot use other osteoporosis treatments. Teriparatide injection contains a synthetic form of natural human hormone called parathyroid hormone (PTH). It works by causing the body to build new bone and by increasing bone strength and density (thickness).