Teriparatide: evidence, FDA status and research

It is a daily injection that builds new bone in people with osteoporosis. In a trial of 1,637 women, new spine breaks fell from 14% to 5%.

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Teriparatide is the bone-building osteoporosis injection, the first drug that grows new bone instead of slowing its loss.

Studies say

A large randomized trial showed fewer spine and non-spine fractures in high-risk postmenopausal women, and two decades of use have not shown the bone cancer signal seen in rats, which is why it grades A.

Why grade A. The Fracture Prevention Trial randomized 1,637 postmenopausal women with prior vertebral fractures to teriparatide or placebo and showed fewer new vertebral and nonvertebral fractures over a median of 21 months. The approved use matches the trial population, and the label has since been expanded on further human data, so the grade is A. ¹²

FDA. Teriparatide is approved by the FDA as Forteo (and as generic and follow-on products) to treat osteoporosis in postmenopausal women and men at high risk of fracture, and glucocorticoid-induced osteoporosis. Approved in 2002; the boxed warning about osteosarcoma and the two-year lifetime limit were removed from the label in November 2020. ²

Written from 2 cited sources. Fact-checked 2026-10-27: 14 claims checked, 0 corrected. Last refreshed 2026-10-27. Not physician reviewed.

What this means for you

What people take it for: Weak bones from osteoporosis
Can a US doctor prescribe it?: Yes, FDA approved for osteoporosis in women after menopause and in men at high risk of breaks.
Properly tested in people?: Yes, in a large controlled trial of 1,637 women.

Evidence checklist

Randomised controlled trial Fracture Prevention Trial, placebo-controlledyes
Human study over 100 people 1,637 postmenopausal womenyes
More than one research group Trial plus two decades of label datayes
Clinical outcomes, not surrogate markers New spine and non-spine fractures fellyes
Human safety data beyond case reports Osteosarcoma warning stayed; no human signalyes

Drawn from the cited studies below. A dash means the sources give no information.

What it is

Teriparatide is a lab-made copy of the first 34 amino acids of human parathyroid hormone. This part of the hormone carries all its activity at the receptor. Parathyroid hormone normally keeps blood calcium steady. When it stays high (as in an overactive parathyroid gland), it strips calcium out of bone. Given as a short pulse by injection under the skin, the same molecule does the opposite. It builds bone. ¹²

Eli Lilly's Forteo was approved in 2002. It was the first anabolic (bone-building) osteoporosis drug. Other osteoporosis medicines in wide use then, such as bisphosphonates, work by slowing bone breakdown. ¹²

How it works

Osteoblasts are the cells that lay down bone. They carry parathyroid hormone receptors. A brief spike of teriparatide increases osteoblast number and activity. It also lowers their rate of programmed cell death. So new bone forms faster than it is removed. Bone density in the spine rises within months. Bone-removing cells are also switched on. That is why the gain slows after about 18 to 24 months. It is also why patients usually move to a drug that blocks breakdown afterward. ¹²

What human research shows

The Fracture Prevention Trial appeared in the New England Journal of Medicine in 2001. It randomized 1,637 postmenopausal women who already had at least one spine fracture. They got one of two teriparatide doses or placebo. Researchers followed them for a median of 21 months. New spine fractures occurred in 14 percent of the placebo group. On the dose later approved, 5 percent had them. That is a 65 percent relative drop. New nonvertebral fragility fractures fell from 6 percent to 3 percent. Spine bone density rose 9 percentage points more than with placebo. ¹

The trial was stopped early. Rats given high doses for most of their lives developed osteosarcoma. So follow-up is shorter than planned. Later claims-database studies linked to cancer registries found no extra osteosarcoma in people treated with teriparatide. The FDA cited them when it revised the label in 2020. ²

Study	Model	Finding
Fracture Prevention Trial (Neer 2001)	Humans, n=1,637 postmenopausal women with prior vertebral fracture, randomized placebo-controlled, median 21 months	New vertebral fractures fell from 14 percent on placebo to 5 percent at the approved dose, with nonvertebral fragility fractures cut roughly in half. ¹
FDA label revision (2020)	Regulatory review of post-marketing cohort studies	No increase in osteosarcoma in teriparatide-treated patients versus unexposed groups; boxed warning and two-year limit removed. ²

Safety

Common side effects in the phase 3 trial were nausea, headache, dizziness and leg cramps. Calcium in the blood rose briefly a few hours after the injection. This was more frequent than with placebo and mostly mild. Blood pressure can drop briefly on standing after the first doses. ¹²

Osteosarcoma remains in the warnings section. The 2020 label change removed the boxed warning and the fixed two-year treatment limit. This allows longer use in patients who stay at high fracture risk. The label still advises against use in people with Paget's disease of bone, unexplained high alkaline phosphatase, prior skeletal radiation, or open growth plates. Hypercalcemia, kidney stones and raised urine calcium are also listed. ²

Questions for your clinician

Am I at high enough fracture risk for teriparatide over other bone drugs?
What follows teriparatide, so the bone gains are kept?
How does the osteosarcoma warning apply to my history?

Questions people ask

Is teriparatide FDA-approved?

Yes, since 2002, as Forteo and later as generic and follow-on teriparatide products. The approved uses are osteoporosis in postmenopausal women and men at high risk of fracture, and osteoporosis caused by long-term steroid treatment. ²

Does teriparatide cause bone cancer?

Rats given high doses for most of their lives developed osteosarcoma. This led to a boxed warning at approval. Human cohort studies linked to cancer registries found no extra cases. In November 2020 the FDA removed the boxed warning and the two-year lifetime limit. Osteosarcoma remains a listed warning. ²

How much does teriparatide reduce fractures?

In the 1,637-woman phase 3 trial, new spine fractures fell by about 65 percent relative to placebo (from 14 percent to 5 percent of women) over a median of 21 months. Nonvertebral fragility fractures fell by about half. ¹

Why do people switch to another drug after teriparatide?

The bone-building effect slows after 18 to 24 months as bone-removing cells catch up. Gains are lost if nothing follows. The usual plan is to follow teriparatide with a drug that blocks bone breakdown, to lock in the new bone. The 2020 label removed the hard two-year cap for patients who stay at high risk. ¹²

Citations

Neer 2001, NEJM: Effect of parathyroid hormone (1-34) on fractures and bone mineral density in postmenopausal women with osteoporosis doi.org
Eli Lilly: Forteo (teriparatide injection) prescribing information uspl.lilly.com