Short answer: Prolia (denosumab) is a 60 mg shot every 6 months, given by a healthcare provider, that slows bone breakdown. Forteo (teriparatide) is a 20 mcg shot you give yourself once a day that builds bone; use past 2 years is only for people still at high risk.12 Their fracture trials were separate; small trials compared bone density only.
| Prolia (denosumab) | Forteo (teriparatide) | |
|---|---|---|
| What it is | RANK ligand (RANKL) inhibitor, which slows bone breakdown1 | Parathyroid hormone analog, PTH(1-34)2 |
| Approved for | Postmenopausal women and men with osteoporosis at high fracture risk; steroid-induced osteoporosis; bone loss on hormone therapy for prostate or breast cancer1 | Postmenopausal women with osteoporosis at high fracture risk; men with primary or hypogonadal osteoporosis; steroid-induced osteoporosis2 |
| Label dose | 60 mg under the skin every 6 months, given by a healthcare provider1 | 20 mcg under the skin once a day, in the thigh or abdomen2 |
| How long | No set limit; stopping raises fracture risk, so move to another bone drug if stopped1 | More than 2 years in a lifetime only if fracture risk stays or becomes high again2 |
| Boxed warning | Severe low calcium in advanced kidney disease (eGFR under 30)1 | None; osteosarcoma in rats is listed as a warning2 |
| New spine fractures, main placebo trial | 2.3% vs 7.2% over 3 years1 | 5.0% vs 14.3%, median 19 months2 |
| Other fractures, same trial | Nonvertebral 6.5% vs 8.0%; hip 0.7% vs 1.2%1 | Nonvertebral 2.6% vs 5.5%2 |
| Half-life | Mean 25.4 days; levels fall over 4 to 5 months1 | About 1 hour2 |
| Storage | Refrigerated; once out, keep at or below 77°F and use within 30 days1 | Refrigerated at all times except when injecting; pen discarded 28 days after first use2 |
Each label reports its own placebo-controlled trial in postmenopausal women. In Prolia's 3-year trial (7,808 women), new spine fractures occurred in 2.3% vs 7.2% on placebo.1 In Forteo's trial (1,637 women, median 19 months), new spine fractures occurred in 5.0% vs 14.3%.2
These numbers come from separate placebo-controlled trials with different people, lengths and methods, so they are not a head-to-head comparison. The women in the Forteo trial were higher risk at the start: 90% already had a spine fracture, vs 23% in the Prolia trial.21
Only for bone density, not fractures. In the DATA trial, 94 postmenopausal women were randomized to teriparatide 20 mcg daily, denosumab 60 mg every 6 months, or both. After 12 months, spine bone density rose 6.2% on teriparatide, 5.5% on denosumab and 9.1% on both; total hip rose 0.7%, 2.5% and 4.9%.3 The published comparisons were of the combination against each drug alone, and using both at once is not an approved regimen in either label.12
In DATA-Switch, the same women swapped drugs for 2 more years. Women who went from teriparatide to denosumab kept gaining bone density, while those who went from denosumab to teriparatide had progressive or temporary bone loss at the hip and wrist. Total hip density at 4 years rose 6.6% in the teriparatide-first group vs 2.8% in the denosumab-first group.4 This was a small trial of bone density, not fractures.
The Prolia label separately warns that stopping Prolia raises fracture risk, including multiple spine fractures, and says to move to another bone-loss drug if it is stopped.1 Any switch is a decision for your prescriber.
More detail: Prolia side effects, Forteo side effects, the Prolia and Forteo dosing schedules, what to do if you miss a Prolia shot or miss a Forteo dose, how to store Forteo, and the Teriparatide guide.