Forteo (teriparatide) is a prescription drug used to treat osteoporosis in adults. The medication comes as a liquid solution in a prefilled pen. It is typically injected under the skin once per day. Each pen contains 2.4 mL of solution, amounting to 600 mcg of Forteo. The strength of Forteo is 250 mcg/mL. The dosage is 20 mcg per injection, usually administered to the thigh or lower abdomen. Forteo may be used for long-term treatment, but it is generally recommended to limit the treatment to 2 years. If there is still a high risk of fractures, your doctor may recommend continuing Forteo. When using Forteo, rotate the injection sites to avoid injecting into the same area every day. If you miss a dose, skip it and take the next dose at the usual scheduled time. Do not inject more than once a day. Overdosing on Forteo can lead to serious side effects like abnormal levels of calcium and phosphorus. If you suspect an overdose, contact your doctor immediately.