Teriparatide is a lab-made copy of the first 34 amino acids of human parathyroid hormone (PTH), the active end of the natural 84-amino-acid hormone. Eli Lilly sells it as Forteo, a once-daily injection pen approved by the FDA in 2002 for osteoporosis in people at high risk of fracture. Unlike most osteoporosis drugs, which slow bone breakdown, teriparatide stimulates new bone formation. That is why it is called a “bone anabolic” drug.
The most important regulatory facts changed in November 2020. FDA removed the boxed warning about osteosarcoma (a bone cancer seen in rats) and relaxed the old 2-year lifetime limit. The current label still describes the rat tumor finding as a warning and keeps a 2-year reference point, but allows longer use when fracture risk stays high. An August 2026 update added a new warning on severe allergic (hypersensitivity) reactions.
This page summarizes what the FDA label, the pivotal trials and FDA’s regulatory record report. It is for education only and is not medical advice.
| Property | Detail |
|---|---|
| Drug class | Parathyroid hormone analog, PTH(1-34); bone-forming osteoporosis drug |
| Brands / approval | Forteo (Eli Lilly), NDA 021318, approved November 26, 2002; Bonsity (2019) and generic teriparatide also approved |
| Route | Subcutaneous injection into the thigh or abdomen |
| Strength | 560 mcg/2.24 mL pen (250 mcg/mL), 28 daily doses of 20 mcg |
| Labeled dose | 20 mcg once daily |
| Half-life (label) | About 1 hour after subcutaneous injection |
| Treatment duration | Beyond 2 years in a lifetime only if fracture risk remains or again becomes high (since November 2020) |
| Boxed warning | None since November 2020 (osteosarcoma boxed warning removed) |
| US status | Prescription drug; not on the DEA Schedule III anabolic steroid list |
| WADA status | Not named on the 2026 Prohibited List |
What it is
Teriparatide has the same sequence as the 34 N-terminal amino acids of human PTH, the region that carries the hormone’s biological activity. Its formula is C₁₈₁H₂₉₁N₅₅O₅₁S₂ and its molecular weight is 4117.8 daltons. Forteo is made in a genetically modified strain of E. coli (FDA label).
Natural PTH is the body’s main regulator of calcium and phosphate. It acts on bone, on the kidney (calcium and phosphate reabsorption) and, indirectly, on calcium absorption from the gut. Teriparatide binds the same PTH receptors with the same affinity as the native hormone.
The key to how it works is the dosing pattern. The label describes two opposite effects of the same hormone:
| Exposure pattern | Effect on bone |
|---|---|
| Brief daily pulse (once-daily injection) | Stimulates osteoblasts (bone-building cells) more than osteoclasts (bone-removing cells). New bone forms on trabecular and cortical surfaces. |
| Continuous excess (as in hyperparathyroidism) | Resorption can outpace formation, which may harm the skeleton. |
“Anabolic” here means bone, not muscle. Teriparatide is sometimes discussed alongside anabolic steroids and recovery peptides. Its approved effects, and every outcome in its pivotal trials, concern bone density and fractures. We found no controlled trials showing that it builds muscle mass or improves athletic performance.
Teriparatide products in the US
| Product | Application | FDA approval |
|---|---|---|
| Forteo (Eli Lilly) | NDA 021318 | November 26, 2002 |
| Bonsity (Alvogen) | NDA 211939 | October 4, 2019 |
| Teriparatide (Amphastar) | ANDA 213641 | December 12, 2025 |
Approval dates are from Drugs@FDA (Forteo; Bonsity; Amphastar). Other teriparatide injections are also listed on DailyMed. The clinical data on this page come from Forteo.
Pharmacokinetics
Teriparatide is a short-lived peptide. A single daily injection produces a brief spike, not a steady level, which matches the “pulse” pattern that favors bone formation. From the FDA label:
| Parameter | Value |
|---|---|
| Absolute bioavailability (subcutaneous) | About 95% |
| Time to peak | About 30 minutes after a 20 mcg dose |
| Time until no longer measurable | Within 3 hours |
| Serum half-life | About 1 hour |
| Volume of distribution (IV) | About 0.12 L/kg |
| Systemic clearance | About 62 L/h in women, 94 L/h in men |
| Exposure in men vs women | 20–30% lower in men (same labeled dose) |
| Severe renal impairment (CrCl under 30 mL/min, n = 5) | AUC up 73%, half-life up 77%; peak not increased |
No formal metabolism studies were done. PTH fragments are thought to be cleaved by non-specific enzymes in the liver and cleared mainly by the kidneys.
The drug’s effect on calcium lasts longer than the drug itself. After a 20 mcg dose, serum calcium starts to rise at about 2 hours, peaks at 4–6 hours (median rise 0.4 mg/dL) and returns to baseline by 16–24 hours.
Approved medical use
The current label approves Forteo for three groups (FDA label):
- postmenopausal women with osteoporosis at high risk for fracture, or who have failed or cannot tolerate other osteoporosis therapy;
- men with primary or hypogonadal osteoporosis, to increase bone mass, under the same high-risk conditions;
- men and women with osteoporosis linked to long-term glucocorticoid use (5 mg/day or more of prednisone or equivalent), under the same high-risk conditions.
The labeled dose is 20 mcg under the skin once daily. The label advises supplemental calcium and vitamin D if dietary intake is inadequate. Because of the risk of a drop in blood pressure on standing, it says the first doses should be given where the patient can sit or lie down. Each pen is discarded 28 days after first use. Teriparatide is not approved for children.
How the duration limit changed
| Label version | Treatment duration wording |
|---|---|
| Before November 2020 | “Use of the drug for more than 2 years during a patient’s lifetime is not recommended” |
| November 2020 to now | Use for more than 2 years in a lifetime “should only be considered” if the patient remains at, or has returned to, high fracture risk |
Sources: FDA label, April 2020; FDA approval letter S-054, November 2020.
What the research shows
Fractures in postmenopausal women
The pivotal Fracture Prevention Trial randomized 1637 postmenopausal women who already had vertebral fractures to daily teriparatide 20 mcg, 40 mcg or placebo (Neer et al., NEJM 2001). Median observation was 21 months. Like the other phase 3 trials, it was stopped early because of the rat osteosarcoma finding (Krege et al., JBMR Plus 2022). All women took calcium and vitamin D.
| Outcome | Placebo | 20 mcg | 40 mcg |
|---|---|---|---|
| New vertebral fracture | 14% | 5% | 4% |
| Relative risk of vertebral fracture | — | 0.35 (95% CI 0.22–0.55) | 0.31 (95% CI 0.19–0.50) |
| New nonvertebral fragility fracture | 6% | 3% | 3% |
| Lumbar spine BMD vs placebo | — | +9 points | +13 points |
| Femoral neck BMD vs placebo | — | +3 points | +6 points |
The 40 mcg dose raised bone density more but did not reduce fractures further, and it caused more side effects. Only 20 mcg was approved.
The label’s analysis of the 20 mcg arm reports an absolute reduction in vertebral fracture of 9.3% (95% CI 5.5–13.1) and a relative reduction of 65% (95% CI 45–78). Lumbar spine BMD (bone mineral density) rose 9.7% vs 1.1% on placebo. Bone biopsies in 35 women showed normal mineralization and normal-quality new bone (FDA label).
Head-to-head with a bisphosphonate (VERO)
The VERO trial was the first to compare two osteoporosis drugs with fractures as the primary outcome. It randomized 1360 postmenopausal women with severe osteoporosis (at least two moderate or one severe vertebral fracture) to teriparatide 20 mcg daily or oral risedronate 35 mg weekly for 24 months, double-blind (Kendler et al., Lancet 2018):
| Outcome at 24 months | Teriparatide | Risedronate | Effect (95% CI) |
|---|---|---|---|
| New vertebral fracture | 5.4% | 12.0% | RR 0.44 (0.29–0.68) |
| Clinical fracture | 4.8% | 9.8% | HR 0.48 (0.32–0.74) |
| Nonvertebral fragility fracture | 4.0% | 6.1% | HR 0.66 (0.39–1.10), not significant |
The trial was funded by Lilly.
Men with osteoporosis
A trial of 437 men with low spine or hip BMD compared daily teriparatide 20 mcg, 40 mcg and placebo (Orwoll et al., JBMR 2003). It was also stopped early, after a median of 11 months, because of the rat finding. At 20 mcg:
- spine BMD rose 5.9% and femoral neck BMD 1.5% above baseline;
- responses were similar regardless of testosterone status, age or baseline BMD;
- fracture outcomes were not studied, which is why the male indication is worded as “to increase bone mass.”
Glucocorticoid-induced osteoporosis
An 18-month double-blind trial randomized 428 adults on long-term glucocorticoids to teriparatide 20 mcg daily or alendronate 10 mg daily (Saag et al., NEJM 2007):
| Outcome | Teriparatide | Alendronate |
|---|---|---|
| Lumbar spine BMD change | +7.2% | +3.4% |
| New vertebral fracture | 0.6% | 6.1% (p = 0.004) |
| Nonvertebral fracture | 5.6% | 3.7% (p = 0.36) |
More patients on teriparatide had at least one high serum calcium reading.
What happens after stopping, and sequencing
BMD gains from teriparatide are not permanent on their own. In the DATA-Switch extension, postmenopausal women who switched from 2 years of teriparatide to denosumab kept gaining bone: spine BMD was up 18.3% at 4 years. Women who switched the other way, from denosumab to teriparatide, had progressive or transient bone loss, especially at the hip and wrist (Leder et al., Lancet 2015). The trial was small (77 women in the analysis). The authors concluded that these results should be considered when choosing the first and the follow-on treatment.
Fracture healing (off-label)
Teriparatide is often discussed online as an injury-recovery drug. The controlled human data on healing fresh fractures are mixed:
| Trial | Design | Result |
|---|---|---|
| Distal radius fracture (Aspenberg et al., JBMR 2010) | 102 postmenopausal women, placebo vs 20 or 40 mcg for 8 weeks | Primary comparison (40 mcg vs placebo) not significant. In a post hoc analysis, 20 mcg shortened median time to healing (7.4 vs 9.1 weeks). |
| Femoral neck fracture (Bhandari et al., Clin Orthop 2016) | 159 patients, 20 mcg vs placebo for 6 months; stopped early for slow enrollment | No difference in revision surgery, radiographic healing or pain. |
| Pelvic fracture (Nieves et al., Osteoporos Int 2022) | 35 older adults, 20 mcg vs placebo for 3 months | No difference in CT healing or pain; physical performance improved only in the teriparatide group. |
A 2021 meta-analysis of randomized trials found that PTH analogues improved functional outcomes but did not change fracture healing rate or pain (Eastman et al., Osteoporos Int 2021). It noted that most trials enrolled older people with osteoporosis and that the evidence is weaker for younger patients without it. Fracture healing is not an approved use.
For soft tissue, a small triple-blind trial randomized 50 adults aged 50–80 to teriparatide 20 mcg daily or placebo for 3 months after arthroscopic rotator cuff repair (Guity et al., JBJS Open Access 2025). At 1 year there was no difference in shoulder function scores or pain, and MRI retear rates were similar (8.7% vs 10%). We found no controlled human trials in muscle or ligament injury.
Side effects and risks
Osteosarcoma: from boxed warning to standard warning
In two-year rat studies, teriparatide caused a dose- and duration-dependent rise in osteosarcoma. The rate reached 40–50% in the high-dose groups, at exposures 3–60 times the human exposure. No bone tumors were seen in an 18-month study of ovariectomized monkeys followed for 3 more years (FDA label).
Because of this, Forteo launched with a boxed warning, a 2-year lifetime limit and required postmarketing cancer surveillance (Krege et al., JBMR Plus 2022). The April 2020 label still carried “WARNING: POTENTIAL RISK OF OSTEOSARCOMA,” which told prescribers to use it only when benefits outweighed this potential risk (FDA label, April 2020).
On November 16, 2020, FDA approved a supplement that removed the boxed warning, relaxed the duration limit, added cutaneous calcification to the warnings and added the surveillance results to the label (FDA approval letter S-054). The human data behind that change:
| Study | Population | Finding |
|---|---|---|
| Osteosarcoma Surveillance Study, 2003–2016 (Gilsenan et al., JBMR 2021) | US cancer registry cases, interviews with 1173 patients | 3 prior teriparatide users vs 4.17 expected; standardized incidence ratio 0.72 (90% CI 0.20–1.86) |
| Forteo Patient Registry, 2009–2019 (Gilsenan et al., Osteoporos Int 2021) | 75,247 patients, 361,763 person-years | 0 cases; authors note follow-up was shorter than expected |
| Two US claims-based studies (FDA label) | 379,283 and 153,316 users | 3 and 0 cases; risk similar to comparators, with limits on confounder control |
For context, the background rate of osteosarcoma in US adults aged 40 or older is about 2.5 cases per million per year (Gilsenan et al., JBMR 2021).
The current label still lists osteosarcoma as a warning. It notes postmarketing case reports, no increased risk in observational studies, and limited data beyond 2 years of use. It says to avoid teriparatide in people at higher baseline risk:
- open growth plates (children and young adults);
- metabolic bone diseases other than osteoporosis, including Paget’s disease;
- bone metastases or a history of skeletal cancer;
- prior radiation therapy involving the skeleton;
- hereditary conditions that predispose to osteosarcoma.
Hypersensitivity (August 2026 update)
In April 2026, FDA notified Lilly of new safety information on hypersensitivity reactions that it determined should be included in the labeling of parathyroid hormone products. The resulting Forteo label update was approved on August 3, 2026 (FDA approval letter S-059). The current label:
- lists anaphylaxis, angioedema and urticaria (hives) reported with PTH analogs, including Forteo;
- says to stop the drug if a reaction occurs, and to stop permanently after a severe one;
- lists a history of severe hypersensitivity to teriparatide or its inactive ingredients as the only contraindication (earlier labels contraindicated any hypersensitivity to teriparatide or its excipients).
Calcium, kidney stones and calciphylaxis
Teriparatide raises blood calcium for several hours after each dose. In the trials, transient hypercalcemia 4–6 hours after dosing occurred at least once in 11% of women and 6% of men, vs 2% and 0% on placebo. It was confirmed on repeat testing in 3% of women and 1% of men. Hypercalcemia above 13 mg/dL has been reported after approval (FDA label).
The label also notes:
- avoid in people with an underlying hypercalcemic disorder such as primary hyperparathyroidism;
- serious calciphylaxis (calcium deposits in small skin vessels) has been reported; risk factors include autoimmune disease, kidney failure, and warfarin or systemic corticosteroid use;
- kidney stone rates were similar to placebo, but people with active or recent stones were not studied;
- serum uric acid rose above normal in 3% vs 1% on placebo, without more gout.
Orthostatic hypotension and other common effects
In short clinical pharmacology studies, 5% of healthy volunteers had brief symptomatic orthostatic hypotension (a drop in blood pressure on standing), usually within 4 hours of one of the first doses. The most common adverse reactions (over 10%) were joint pain, pain and nausea.
| Event (pooled trials, n = 691 per group) | Teriparatide | Placebo |
|---|---|---|
| Arthralgia | 10.1% | 8.4% |
| Nausea | 8.5% | 6.7% |
| Dizziness | 8.0% | 5.4% |
| Leg cramps | 2.6% | 1.3% |
| Syncope | 2.6% | 1.4% |
| Serious adverse events | 16% | 19% |
In the glucocorticoid trial, nausea (14% vs 7%), pneumonia (6% vs 3%) and herpes zoster (3% vs 1%) were more common with teriparatide than with alendronate (FDA label).
Interactions and special populations
- Digoxin. The calcium rise may predispose to digitalis toxicity, so the label flags this combination.
- Diuretics. Hydrochlorothiazide and IV furosemide caused only small, not clinically important changes in calcium in label studies.
- Pregnancy and breastfeeding. There are no human data. The label says to consider stopping when pregnancy is recognized and not to breastfeed.
- Overdose. Medication errors of up to 800 mcg (a whole pen) have caused nausea, weakness and low blood pressure, with no reported deaths.
- Antibodies. Antibodies to teriparatide appeared in 3% of women in the pivotal trial, without effects on calcium or BMD response.
Legal status and use outside medicine
In the US, teriparatide is a prescription drug. It is not a scheduled anabolic steroid (21 CFR 1308.13). It is not named on the WADA 2026 Prohibited List. The list’s growth-factor class (S2.3) is open-ended: it covers named examples plus other growth factors or modulators affecting muscle, tendon or ligament protein synthesis, vascularisation or regenerative capacity. PTH analogs are not among the named examples.
Teriparatide sold as a “research peptide” outside pharmacies is not an FDA-approved product, and its identity, dose and sterility are not verified. The approved pen also needs refrigeration at all times except during use.
Key takeaways
- A bone-building hormone fragment. Teriparatide is the active 1-34 piece of parathyroid hormone. Brief daily exposure builds bone, while continuous PTH excess can weaken it.
- Proven fracture reduction. At 20 mcg/day it cut new vertebral fractures by about two-thirds vs placebo and outperformed risedronate in severe osteoporosis.
- The boxed warning is gone. FDA removed the osteosarcoma boxed warning in November 2020 after large surveillance studies found no increase in human osteosarcoma. The rat finding remains a standard warning.
- The 2-year limit is now conditional. Use beyond 2 years in a lifetime may be considered if fracture risk remains or returns to high, though long-term data are limited.
- Watch calcium and allergy. Transient high calcium, calciphylaxis and, since August 2026, severe hypersensitivity are the main labeled risks.
- Not a muscle or injury drug. There are no controlled data showing muscle or performance effects, and fracture- and tendon-healing trials show mixed or null results.
Sources
- Eli Lilly and Company. Forteo (teriparatide injection), prescribing information, revised 08/2026. DailyMed; Drugs@FDA, NDA 021318.
- Eli Lilly and Company. Forteo (teriparatide injection), prescribing information, 04/2020 (with osteosarcoma boxed warning). FDA.
- US Food and Drug Administration. NDA 021318/S-054 supplement approval letter. November 16, 2020. FDA.
- US Food and Drug Administration. NDA 021318/S-059 supplement approval letter. August 3, 2026. FDA.
- US Food and Drug Administration. Drugs@FDA: Bonsity (teriparatide), NDA 211939; Teriparatide (Amphastar), ANDA 213641. Drugs@FDA, NDA 211939; Drugs@FDA, ANDA 213641.
- Neer RM, Arnaud CD, Zanchetta JR, et al. Effect of parathyroid hormone (1-34) on fractures and bone mineral density in postmenopausal women with osteoporosis. N Engl J Med. 2001;344(19):1434–1441. PubMed.
- Kendler DL, Marin F, Zerbini CAF, et al. Effects of teriparatide and risedronate on new fractures in post-menopausal women with severe osteoporosis (VERO): a multicentre, double-blind, double-dummy, randomised controlled trial. Lancet. 2018;391(10117):230–240. PubMed.
- Orwoll ES, Scheele WH, Paul S, et al. The effect of teriparatide [human parathyroid hormone (1-34)] therapy on bone density in men with osteoporosis. J Bone Miner Res. 2003;18(1):9–17. PubMed.
- Saag KG, Shane E, Boonen S, et al. Teriparatide or alendronate in glucocorticoid-induced osteoporosis. N Engl J Med. 2007;357(20):2028–2039. PubMed.
- Leder BZ, Tsai JN, Uihlein AV, et al. Denosumab and teriparatide transitions in postmenopausal osteoporosis (the DATA-Switch study): extension of a randomised controlled trial. Lancet. 2015;386(9999):1147–1155. PubMed.
- Aspenberg P, Genant HK, Johansson T, et al. Teriparatide for acceleration of fracture repair in humans: a prospective, randomized, double-blind study of 102 postmenopausal women with distal radial fractures. J Bone Miner Res. 2010;25(2):404–414. PubMed.
- Bhandari M, Jin L, See K, et al. Does Teriparatide Improve Femoral Neck Fracture Healing: Results From A Randomized Placebo-controlled Trial. Clin Orthop Relat Res. 2016;474(5):1234–1244. PubMed.
- Nieves JW, Cosman F, McMahon D, et al. Teriparatide and pelvic fracture healing: a phase 2 randomized controlled trial. Osteoporos Int. 2022;33(1):239–250. PubMed.
- Eastman K, Gerlach M, Piec I, et al. Effectiveness of parathyroid hormone (PTH) analogues on fracture healing: a meta-analysis. Osteoporos Int. 2021;32(8):1531–1546. PubMed.
- Krege JH, Gilsenan AW, Komacko JL, Kellier-Steele N. Teriparatide and Osteosarcoma Risk: History, Science, Elimination of Boxed Warning, and Other Label Updates. JBMR Plus. 2022;6(9):e10665. PubMed.
- Gilsenan A, Midkiff K, Harris D, et al. Teriparatide Did Not Increase Adult Osteosarcoma Incidence in a 15-Year US Postmarketing Surveillance Study. J Bone Miner Res. 2021;36(2):244–251. PubMed.
- Gilsenan A, Harris D, Reynolds M, et al. Long-term cancer surveillance: results from the Forteo Patient Registry Surveillance Study. Osteoporos Int. 2021;32(4):645–651. PubMed.
- Guity MR, Hoveidaei AH, Farsani AS, et al. Effectiveness of Teriparatide (rhPTH) in Enhancing Functional Recovery After Arthroscopic Rotator Cuff Repair: A Triple-Blind Randomized Clinical Trial. JB JS Open Access. 2025;10(3):e25.00035. PubMed.
- US Drug Enforcement Administration. Schedules of controlled substances: Schedule III. 21 CFR 1308.13. eCFR.
- World Anti-Doping Agency. World Anti-Doping Code International Standard: Prohibited List 2026. WADA 2026 Prohibited List.