Forteo (Teriparatide): How It Builds Bone in Osteoporosis
Forteo builds bone by copying the working front end of parathyroid hormone (PTH), the body's main calcium boss. Its drug, teriparatide, is the first 34 of the hormone's 84 amino acids. Kept high all the time, PTH can wear bone down. Given as a brief pulse that fades within hours, the same signal makes the bone-building cells get ahead.
Eli Lilly makes Forteo, and US doctors can prescribe it for osteoporosis at high fracture risk. When the FDA approved it in 2002, it became the first osteoporosis drug that builds new bone. Its story has a twist: its big fracture trial stopped early because of a finding in rats.
Key facts
What it is: The FDA label calls it teriparatide, PTH 1-34, a 34 amino acid copy of the active front end of human parathyroid hormone.
Status, checked 8 November 2026: Drugs@FDA lists it as prescription only in the US, for osteoporosis at high fracture risk, with generic versions approved since 2023.
What it targets: The PTH1 receptor on bone cells. The label says it binds there just like your own PTH.
The twist: Constant PTH can break bone down, but a pulse that is half gone within about an hour favors the builder cells.
How it is made: By Escherichia coli bacteria that carry the human recipe through recombinant DNA.
Main trial result: The label reports new spine fractures in 5.0% of women on Forteo against 14.3% on placebo.
Sources: Forteo prescribing information, FDA, August 2026; Drugs@FDA, NDA 021318 (Forteo); openFDA records for every listed teriparatide product
What is teriparatide made of?
Teriparatide is a short protein chain: the first 34 amino acids of human parathyroid hormone. The full hormone is 84 amino acids long. The FDA label calls the first 34 the biologically active region, and teriparatide matches them exactly. Its formula is C181H291N55O51S2, and it weighs 4,117.8 daltons.
A bacterial factory. Lilly makes the chain with a strain of E. coli bacteria that carries the human recipe. This method is called recombinant DNA. FDA's 2002 approval letter names the product "teriparatide (rDNA origin)" for that reason. Not every teriparatide is made the same way. Bonsity, approved in 2019, is grown in a different bacterium, Pseudomonas fluorescens, according to FDA's review.
Ready made. The label describes Forteo as a clear, colorless liquid. Many research peptides arrive as a dry powder instead. That is why our peptide reconstitution calculator works out the water math for those. Forteo needs none of that.
An odd date on the label. The top of the current label says "Initial U.S. Approval: 1987." Forteo itself was approved on 26 November 2002. The label does not explain the earlier year, so we do not guess which product it refers to.
Sources: Forteo prescribing information, FDA, August 2026; FDA approval letter for Forteo, 26 November 2002; FDA review of Bonsity (PF708), 2019; Drugs@FDA, NDA 021318 (Forteo)
Which receptor does teriparatide fit?
Teriparatide fits the PTH1 receptor, the same lock that your own parathyroid hormone turns. The label says teriparatide binds this receptor just as strongly as the first 34 amino acids of PTH. It also has the same effects on bone and kidney. In the body, PTH is the main boss of calcium and phosphate. It acts on bone and on the kidneys. It also changes how much calcium the gut takes in.
What kind of lock. A 2015 review describes PTH1 as a family B G-protein-coupled receptor. It sits in the cell surface and passes a message inside when a key lands on it. It answers to two natural keys: PTH and a cousin hormone, PTHrP. A 2002 review places it on several kinds of bone cell. These are the builders (osteoblasts), the young cells that will become builders, osteocytes buried in bone, and the thin cells that line resting bone.
A related drug. Abaloparatide, sold as Tymlos, is built on the cousin key, PTHrP, and its label says it also switches on PTH1. Our Tymlos article takes that drug apart in turn.
Sources: Forteo prescribing information, FDA, August 2026; PTH1 receptor review, Nature Reviews Endocrinology 2015; PTH drugs for osteoporosis, review 2002; Tymlos (abaloparatide) label, openFDA
How does teriparatide build bone?
Teriparatide builds bone by tipping a cycle your skeleton runs all the time. It is called remodeling. First, breaker cells called osteoclasts dig out a patch of old bone. Then builder cells called osteoblasts fill the hole with new bone. Whichever crew does more decides whether bone is gained or lost.
Timing decides who wins. The FDA label says teriparatide's effect on the skeleton depends on the pattern of exposure. A short exposure favors the builders over the breakers. Constant excess PTH, as in hyperparathyroidism, may harm the skeleton because breaking can run ahead of building. Teriparatide fits the short pattern: half of it is gone from the blood in about an hour.
| Question | Brief pulse | Constantly high |
|---|---|---|
| How long PTH stays high | About an hour: half of the drug is gone from the blood in that time | All the time |
| Real-world example | Teriparatide (Forteo) | Hyperparathyroidism, an overactive parathyroid gland |
| Which crew gets ahead | The builders (osteoblasts) | The breakers (osteoclasts) can outpace the builders |
| Effect on the skeleton | More bone mass and stronger bone in people | The label says it may harm the skeleton |
| How well understood | Much of the cell detail comes from mice and lab dishes | Known from the disease itself |
Why the builders get ahead. A 2007 review explains that pulsed PTH raises the number of builder cells. There end up being more than each hole needs, so every patch gets a little extra bone. One big reason is that the builder cells live longer, because PTH delays their planned death. That part was shown at least in mice. The same review says the full mechanism is still not completely understood. Most of the fine detail comes from animal and cell studies.
What shows up in people. The label lists three effects in humans. Markers of both bone building and bone breaking go up, yet skeletal mass and bone strength still increase. So both crews speed up, and the builders win.
Sources: Forteo prescribing information, FDA, August 2026; How pulsed PTH builds bone, Bone 2007
Why is a short-lived drug the point?
Teriparatide is useful because it does not last. That makes it the odd one out in this series. Semaglutide, covered in our oral semaglutide episode, was redesigned to stay around. The Wegovy label gives it a half-life of about a week. Cagrilintide, from our amylin episode, carries a fatty tail for the same reason.
For those drugs a long stay is the goal. The vial math for the shot form of semaglutide sits in our semaglutide reconstitution calculator. For teriparatide, a long stay would look more like hyperparathyroidism. Its job is to switch the receptor on, then get out of the way.
Sources: Forteo prescribing information, FDA, August 2026; Wegovy (semaglutide) label, openFDA
Where did Forteo come from?
Forteo came out of a long hunt for a drug that could add bone, not just save it. Before it, the main osteoporosis drugs were bisphosphonates, calcitonin, estrogens and SERMs. A 2002 review explains that all of them target the breaker cells to slow bone loss. None of them can directly build new bone.
An early hint, 1980. A study in the BMJ gave PTH 1-34 to 21 people with osteoporosis. Spongy bone volume in the hip bone grew by about 70% on average. The new bone looked normal under the microscope. The authors thought it might help spine fractures, since spine bones are mostly spongy bone. There was no comparison group, so it was a hint, not proof.
| When | What happened |
|---|---|
| 1980 | A 21-patient study gives PTH 1-34 to people with osteoporosis. Spongy bone in the hip bone grows about 70% on average, with no comparison group. |
| Nov 2000 | Lilly files its new drug application with the FDA. |
| 2001 | The fracture trial is published in May. An FDA advisory committee recommends approval. |
| 26 Nov 2002 | FDA approves Forteo, with a boxed warning about rat bone cancer, a 2-year limit, and a promise to watch for that cancer in people. |
| 10 Jun 2003 | The EU authorises the same drug as Forsteo. |
| 2003 | The US osteosarcoma surveillance study begins collecting cases. |
| 22 Jul 2009 | Osteoporosis linked to long-term steroid treatment is added. A formal safety program (REMS) is approved the same day. |
| 28 Apr 2017 | FDA releases Forteo from the REMS requirement. |
| 4 Oct 2019 | Bonsity, a separate teriparatide made in a different bacterium, is approved. |
| 16 Nov 2020 | FDA approves a label change that removes the boxed warning and drops the flat 2-year cap. |
| 16 Nov 2023 | The first generic teriparatide products, from Teva and Apotex, are approved. |
| 3 Aug 2026 | The newest label adds a warning about serious allergic reactions. |
The first of its kind. A 2017 review calls teriparatide the first anabolic agent approved to treat osteoporosis, in 2002. The 2002 approval covered women past menopause at high fracture risk. It also covered building bone mass in high-risk men with primary or low-testosterone osteoporosis.
Sources: PTH drugs for osteoporosis, review 2002; First PTH 1-34 bone study, BMJ 1980; FDA approval letter for Forteo, 26 November 2002; Drugs@FDA, NDA 021318 (Forteo); EMA page for Forsteo; 15-year osteosarcoma surveillance, JBMR 2021; FDA letter ending the Forteo REMS, 2017; FDA review of Bonsity (PF708), 2019; FDA letter approving the 2020 label change; openFDA records for every listed teriparatide product; FDA letter for the 2026 label update; Anabolic osteoporosis drugs, review 2017
What did the Forteo fracture trial find?
The Forteo fracture trial found far fewer new spine fractures than placebo. Published in 2001, it enrolled 1,637 women past menopause who already had spine fractures. They were randomly put in one of two PTH 1-34 groups or on placebo, a dummy treatment. The FDA label reports the group that matches Forteo. At least one new spine fracture showed up in 14.3% of women on placebo and 5.0% on Forteo.
That is a 65% relative drop, or about 9 fewer women with a new spine fracture per 100. Fractures elsewhere in the body fell from 5.5% to 2.6%, a 53% relative drop. The trial paper adds that side effects were minor, mostly occasional nausea and headache.
| Trial | Who | Compared with | Main result |
|---|---|---|---|
| Women past menopause | 1,637 women, most with spine fractures already | Placebo | New spine fractures 14.3% on placebo and 5.0% on Forteo. Other fractures 5.5% and 2.6%. Spine bone density up 9.7% against 1.1%. |
| Men | 437 men with primary or low-testosterone osteoporosis | Placebo | Spine bone density up 5.9% against 0.5%. This trial measured density, not fractures. |
| Steroid-linked osteoporosis | 428 men and women on long-term steroids | Another osteoporosis drug | Spine bone density up 7.2% over 18 months. The label does not print the comparison drug's results. |
These are trial averages, not promises. Many of the spine fractures counted were found on X-rays and caused no symptoms, which the label points out.
Sources: Fracture trial, New England Journal of Medicine 2001; Forteo prescribing information, FDA, August 2026
Why did rats stop the Forteo trial?
Rats stopped the Forteo trial because a lifetime rat study turned up bone cancer. A 2022 review by Lilly scientists says the fracture trial was planned for 3 years. It stopped after a median of about 19 months of treatment. That was when the rat study showed osteosarcoma, a cancer that starts in bone. The authors work for the maker. So we note that the FDA label tells the same rat story in its own words.
What the rats showed. According to the label, Fischer 344 rats got teriparatide for 24 months, starting at 2 months old. Their exposure was 3, 20 and 60 times what people get. Osteosarcoma rose with exposure and appeared in every treated group. In the highest groups it reached 40% to 50%. Untreated rats had none. The label adds that the tumors came with a large increase in bone mass and patches of overgrown builder cells.
Age and time. A second rat study found that tumors depended on both the amount and the length of exposure. Mature rats were no less likely to get them than young ones. Monkeys told a different story. In a long-term study, 30 monkeys were treated for 18 months and watched for 3 more years. No bone tumors were found.
The 2002 compromise. FDA approved Forteo with a boxed warning about the rat finding. The first label also said use for more than 2 years was not recommended. The FDA approval letter also recorded a promise from Lilly. It would run a 10-year surveillance program to check whether Forteo is linked to osteosarcoma in people.
Sources: Lilly review of the osteosarcoma history, JBMR Plus 2022; Forteo prescribing information, FDA, August 2026; First Forteo label, 2002; FDA approval letter for Forteo, 26 November 2002
What did 15 years of human data show?
Fifteen years of US data did not detect a rise in osteosarcoma among people who had used teriparatide. The surveillance study began in 2003 and gathered cases from US cancer registries through 2016. From the normal background rate, researchers expected about 4.17 cases among teriparatide users. They found 3. That gives a ratio of 0.72, where 1 would mean the usual rate.
The fine print. The study could interview only 24% of the people with osteosarcoma. Its 90% range for the ratio runs from 0.20 to 1.86, wide enough to include 1. Its authors came from RTI Health Solutions and Lilly. So the honest summary is that no increase was seen, which is not the same as proof of zero risk.
Two more checks. The label adds two US claims-database studies. They found 3 and 0 osteosarcoma cases among 379,283 and 153,316 Forteo users. The label says the risk looked similar to comparison groups. It also says to read the results with caution, because some other factors could not be measured.
Sources: 15-year osteosarcoma surveillance, JBMR 2021; Forteo prescribing information, FDA, August 2026
What changed on the Forteo label in 2020?
In 2020 the Forteo label lost its boxed warning. Lilly filed the change on 16 January 2020, and the FDA approved it on 16 November 2020. The approval letter lists four changes to the prescribing information:
- The osteosarcoma boxed warning was removed.
- The treatment length section was changed. The flat 2-year cap was replaced. The label now says longer use should only be considered if fracture risk stays high or comes back.
- Skin calcium deposits, including a serious form called calciphylaxis, were added to the high calcium warning.
- The long-term surveillance findings were added to the side effects section.
What stayed. The current label still says osteosarcoma has been reported in patients after marketing, though studies in people have not shown a higher risk. It also says data beyond 2 years are limited. And it still asks prescribers to avoid Forteo in people with a higher baseline risk of this cancer, listed in the next section.
Sources: FDA letter approving the 2020 label change; Forteo label after the 2020 change; Forteo prescribing information, FDA, August 2026
What are the side effects of Forteo?
The most common side effects of Forteo are joint pain, pain and nausea, which the label summary lists above 10%. The rates depend on the trial. In the two main placebo trials, with 1,382 women and men, nausea was 8.5% on Forteo. In the steroid-linked osteoporosis trial it was 14%, against 7% on the comparison drug. In those two main trials, these effects were reported more often on Forteo than on placebo:
| Effect | Forteo | Placebo |
|---|---|---|
| Joint pain | 10.1% | 8.4% |
| Nausea | 8.5% | 6.7% |
| Dizziness | 8.0% | 5.4% |
| Headache | 7.5% | 7.4% |
| Depression | 4.1% | 2.7% |
| Leg cramps | 2.6% | 1.3% |
| Fainting | 2.6% | 1.4% |
Calcium and blood pressure. Forteo can push blood calcium up for a few hours. In the trials, 11% of women and 6% of men on Forteo had at least one brief high reading. On placebo it was 2% and 0%. In short studies of healthy volunteers, 5% had a brief blood pressure drop on standing. It cleared on its own.
Warnings on the label:
- Serious allergic reactions, including anaphylaxis and swelling, added in August 2026 for all parathyroid hormone products. Anyone who has had a severe reaction to teriparatide must not use it.
- Osteosarcoma, covered in the rat and surveillance sections above.
- High calcium, and skin calcium deposits including calciphylaxis. It is to be avoided in people with a known high calcium disorder.
- Kidney stones: rates matched placebo, but it has not been studied in people with active stones.
- A brief blood pressure drop on standing, as above.
- Digoxin: higher calcium may raise the risk of digoxin side effects.
Who should avoid Forteo?
The label names these groups:
- Anyone who has had a severe allergic reaction to teriparatide or the other ingredients. This is the one firm contraindication.
- Children and young adults whose growth plates are still open. Forteo is not approved for children.
- People with Paget's disease of bone or other metabolic bone diseases besides osteoporosis.
- People whose cancer has spread to bone, or who have had a skeletal cancer.
- People who have had radiation treatment involving the skeleton.
- People with inherited conditions that raise the chance of osteosarcoma.
- People with a known high calcium disorder, such as primary hyperparathyroidism.
The label also says breastfeeding is not recommended. How these risks weigh up for one patient is a question for the people treating them.
Sources: Forteo prescribing information, FDA, August 2026; FDA letter for the 2026 label update
Who is Forteo approved for?
Forteo is approved in the US for three groups with osteoporosis. Each must be at high risk of fracture, or have tried other osteoporosis drugs that failed or caused problems:
- Women past menopause with osteoporosis. For them the label says it lowers the risk of spine and other fractures.
- Men with primary or low-testosterone (hypogonadal) osteoporosis, to increase bone mass.
- Men and women whose osteoporosis is linked to long-term steroid (glucocorticoid) treatment. This use was added on 22 July 2009.
The label defines high risk as a past osteoporosis fracture or several risk factors for one. Forteo is not approved for children.
Sources: Forteo prescribing information, FDA, August 2026; Drugs@FDA, NDA 021318 (Forteo)
Is Forteo still approved, and is there a generic?
Yes on both. As of 8 November 2026, Drugs@FDA lists Forteo as a prescription drug under Lilly's application, NDA 021318. Its newest label change was approved on 3 August 2026. FDA now lists several other teriparatide products. Five are rated AP, which means FDA treats them as equivalent to Forteo.
| Product | Company and application | Approved | Note |
|---|---|---|---|
| Forteo | Eli Lilly, NDA 021318 | 26 November 2002 | The original. Prescription. |
| Bonsity | Alvogen, NDA 211939 | 4 October 2019 | Made in Pseudomonas fluorescens bacteria. No equivalence code. |
| Teriparatide (generic) | Teva, ANDA 208569 | 16 November 2023 | Rated AP, equivalent to Forteo. |
| Teriparatide (generic) | Apotex, ANDA 211097 | 16 November 2023 | Rated AP. |
| Teriparatide | Almaject, NDA 218771 | 4 June 2024 | Rated AP. |
| Teriparatide (generic) | Amphastar, ANDA 213641 | 12 December 2025 | Rated AP. |
| Teriparatide (generic) | Dr. Reddy's, ANDA 214412 | 23 October 2026 | Rated AP. The newest. |
In the EU the same drug is called Forsteo, authorised since 10 June 2003 and still listed as authorised. Most of the US copies were approved through generic drug applications, called ANDAs. Being listed by FDA does not show that a product is on pharmacy shelves today. Our medical review policy explains how we check approval facts before they go live.
Sources: Drugs@FDA, NDA 021318 (Forteo); openFDA records for every listed teriparatide product; FDA review of Bonsity (PF708), 2019; EMA page for Forsteo
What else do people ask about Forteo?
What is Forteo?+
Forteo is the brand name for teriparatide, a prescription osteoporosis drug from Eli Lilly. The FDA approved it on 26 November 2002. It is a lab-made copy of the first 34 building blocks of parathyroid hormone, the part that does the work. It was the first osteoporosis drug that builds new bone instead of only slowing bone loss.
What are the worst side effects of Forteo?+
The most serious problems in the label are rare. They include severe allergic reactions such as anaphylaxis, which mean stopping the drug for good. They also include very high blood calcium, and calciphylaxis, a painful buildup of calcium in the skin. Osteosarcoma has been reported in patients after marketing, though studies in people have not shown a higher risk. Most people in the trials had milder effects, such as joint pain, nausea or dizziness.
Which is better, Forteo or Prolia?+
Neither is better for everyone, because they work in opposite ways. Prolia (denosumab) is an antibody that blocks RANKL, a signal the breaker cells need, so bone breakdown falls. Forteo pushes the builder cells instead. Both labels cover osteoporosis at high fracture risk in women past menopause, in men, and when it is linked to steroids. This page does not compare them head to head, and the choice belongs to a patient and their doctor.
Is weight gain a side effect of Forteo?+
Weight gain is not on the label. Its main side effect table lists every event that hit at least 2% of Forteo users and was more common than on placebo. Weight change is not one of them. Nor is it among the reports collected after the drug went on sale. Anyone who notices a change on any medicine can raise it with their doctor.
What is teriparatide?+
Teriparatide is the drug inside Forteo, and also inside Bonsity and several generic products. The FDA label calls it a recombinant human parathyroid hormone analog, or PTH 1-34. Recombinant means it is made by microbes given the human gene. In Forteo those microbes are E. coli bacteria.
What is the difference between Forteo and teriparatide?+
Teriparatide is the drug, and Forteo is the Eli Lilly brand of it. Other products contain teriparatide too. Generic versions from several companies are rated by the FDA as equivalent to Forteo. Bonsity is another teriparatide product, grown in a different bacterium, and it has no equivalence rating. All of them are prescription only in the US.
Who should not take teriparatide?+
The label lists one firm rule: no one who has had a severe allergic reaction to teriparatide or its other ingredients. It also asks prescribers to avoid it in people with a higher baseline risk of bone cancer. That covers open growth plates, Paget's disease of bone, cancer in the bone, past radiation to the skeleton and some inherited conditions. People with a high calcium disorder, such as primary hyperparathyroidism, are on the avoid list too.
How long has Forteo been on the market?+
The FDA approved Forteo on 26 November 2002, so by November 2026 it has been approved in the US for almost 24 years. The European Union authorised it as Forsteo on 10 June 2003. These dates come from FDA and EMA records. Those records give approval dates, not the day the first box was sold.
What is the classification of Forteo?+
Forteo is a parathyroid hormone analog. Its label lists it as PTH 1-34. By how it works it is an anabolic, or bone-building, osteoporosis drug. That sets it apart from antiresorptive drugs such as bisphosphonates, which slow the cells that break bone down. It is a prescription drug in the US.
What is PTH 1-34?+
PTH 1-34 means the first 34 amino acids of parathyroid hormone, out of 84 in the full hormone. The FDA label calls those first 34 the biologically active region. Teriparatide has exactly that sequence. It binds the same receptor as the full hormone, with the same strength.
What is the mechanism of action of Forteo?+
Forteo acts on the PTH1 receptor, the same receptor the body's own parathyroid hormone uses. The label says the result depends on the pattern of exposure. A short exposure stimulates the bone-building osteoblasts more than the bone-removing osteoclasts, so new bone forms on both spongy and dense bone surfaces. The label adds that teriparatide is not expected to build up in bone or other tissues.
How does Forteo work?+
Forteo works by switching on the PTH1 receptor on bone cells for a short time, then fading. Half of it is gone from the blood in about an hour. That brief on and off pattern favors the cells that build bone over the cells that remove it. So new bone forms. When natural PTH stays high all the time, as in hyperparathyroidism, the label says it may harm the skeleton instead.
Is Forteo effective for osteoporosis?+
In its main trial, yes. Among women past menopause with osteoporosis, 14.3% on placebo had a new spine fracture against 5.0% on Forteo. That is a 65% relative drop. Other fractures fell from 5.5% to 2.6%. Those numbers are group averages from a single trial, and no single patient is promised the same result. Whether it fits a given patient is a question for their doctor.
What is the success rate of Forteo?+
There is no single success rate, so it helps to look at what the trials measured. In the women's trial, spine bone density went up from its starting point in 96% of women on Forteo, and 72% gained at least 5%. New spine fractures showed up in 5.0% on Forteo and 14.3% on placebo. In the men's trial, spine bone density rose in 94% of men.
How long does it take Forteo to start working?+
In the label's trials, spine bone density was clearly higher than at the start by 3 months, in women and in men. It kept rising for the rest of the treatment period. The fracture results were counted over the whole women's trial, which ran a median of about 19 months on the drug. The label does not predict when any one person will see a change.
What are the side effects of Forteo?+
The label summary names joint pain, pain and nausea as the most common, above 10%. Nausea was 8.5% against 6.7% on placebo in the two main trials, and 14% against 7% in the steroid trial. Dizziness and leg cramps were also more common than on placebo. Blood calcium can run high for a few hours. A few healthy volunteers had a brief blood pressure drop on standing. The warnings also cover serious allergic reactions, skin calcium deposits, kidney stones and the rat bone cancer finding.
Does Forteo cause osteosarcoma?+
In rats, yes: osteosarcoma rose with exposure in a lifetime study. In people, no increase has been seen so far. A 15-year US study expected about 4 cases among patients who had used teriparatide and found 3. Two claims-database studies found 3 and 0 cases among more than 530,000 users combined. The label still notes rare reports in patients and asks prescribers to avoid it in people at higher baseline risk.
Why was the Forteo boxed warning removed?+
Because the human data did not show the rat signal. In 2020 Lilly sent the FDA the long-term surveillance results. On 16 November 2020 the FDA approved a label change that removed the boxed warning. The same change dropped the flat 2-year limit. In its place is a narrower statement for patients whose fracture risk stays high or comes back.
Is there a generic teriparatide?+
Yes. As of 8 November 2026 the FDA lists generic teriparatide from Teva and Apotex, both approved on 16 November 2023. Later ones came from Amphastar and from Dr. Reddy's. An Almaject version is also rated equivalent to Forteo. Bonsity is a separate teriparatide product approved in 2019, made in a different bacterium. All are prescription only.
Is Forteo the same as Tymlos?+
No. Tymlos is abaloparatide, a copy of a related hormone called PTHrP, and it works on the same PTH1 receptor. It has been a US prescription drug since 28 April 2017. Our Tymlos article sets out how the two differ.
Sources: Forteo prescribing information, FDA, August 2026; FDA approval letter for Forteo, 26 November 2002; Anabolic osteoporosis drugs, review 2017; Fracture trial, New England Journal of Medicine 2001; 15-year osteosarcoma surveillance, JBMR 2021; Lilly review of the osteosarcoma history, JBMR Plus 2022; FDA letter approving the 2020 label change; Drugs@FDA, NDA 021318 (Forteo); openFDA records for every listed teriparatide product; FDA review of Bonsity (PF708), 2019; EMA page for Forsteo; Tymlos (abaloparatide) label, openFDA; Prolia (denosumab) label, openFDA
What did we learn about Forteo?
Forteo is a 34-link copy of the front end of PTH. It turns the bone receptor on briefly and then fades, so the builder cells get ahead of the breakers. That made it the first osteoporosis drug to build bone. Its rat finding shaped its label for 18 years. Then 15 years of cancer registry data, plus claims records on more than half a million users, did not detect a rise. The boxed warning came off in 2020.
Molecule Mechanics animates the labels and trial papers behind peptide medicines, one drug per episode. Nothing in the series is personal medical advice. An ElevenLabs AI voice reads the script over original animation, and each video description carries its full source list. The series began with how tirzepatide works and then stayed mostly with weight and blood sugar drugs.
How abaloparatide differs from Forteo is laid out on the Tymlos page. Among the experimental drugs readers ask about most is retatrutide, which our retatrutide calculator covers. Found a mistake here? Our corrections policy shows how to flag it.
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Sources: The Molecule Mechanics channel; 15-year osteosarcoma surveillance, JBMR 2021; Forteo prescribing information, FDA, August 2026
Peptides Vietnam wrote this page to teach, and it is not medical advice. It restates what the Forteo label, FDA records and published studies report. Decisions about a prescription drug belong to a patient and the clinician who treats them.