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Peptide drug (FDA approved)Human trialsFDA approved

Triptorelin

Triptorelin

Last reviewed October 27, 2026 · 13 sources · Written for general readers · Compare with another compound →

The bottom line

Triptorelin is an FDA approved drug sold as Trelstar for advanced prostate cancer and Triptodur for puberty that starts too early in children.[1][2] It causes a short surge in sex hormones and then shuts them down, which is the point of both uses.[1] Some people try it to restart their own testosterone after steroids, but we found no trial showing this works.[3][4]

Where the evidence stands

What it is

Triptorelin is a lab made version of GnRH, the brain hormone that controls sex hormones. One of its 10 amino acids is swapped for a mirror image form of tryptophan (D tryptophan).[1][5]

Trelstar, approved in 2000, is a prescription injection for advanced prostate cancer.[6][1]

Triptodur, approved in 2017, treats central precocious puberty, meaning puberty that starts too early because the brain switches it on too soon, in children 2 and older.[7][2]

In research trials, triptorelin shots have also been used to switch off the ovaries in women with breast cancer, either to protect them during chemotherapy or as part of hormone treatment.[8][9]

Online, it is promoted to people coming off steroids as a way to restart natural testosterone.[3] The claims section below checks this against the evidence.

Name
Triptorelin (Triptorelin)
Other names
Trelstar, Triptodur, triptorelin pamoate, triptorelin acetate
Type
Peptide drug (FDA approved)
Sequence
pGlu-His-Trp-Ser-Tyr-D-Trp-Leu-Arg-Pro-Gly-NH2
CAS number
57773-63-4
Formula
C64H82N18O13
Molecular weight
About 1311 g/mol

How it works

Triptorelin acts on the same pituitary switch as natural GnRH, but it keeps the switch pressed.[1]

  • After the first dose, LH, FSH, testosterone and estrogen rise for a short time.[1]
  • With continued exposure, LH and FSH fall and the testes make far less testosterone, usually within 2 to 4 weeks.[1]
  • In most men with prostate cancer, testosterone drops to castration levels within four weeks. These effects usually reverse after the drug is stopped.[1]
  • In children with early puberty, the same shutdown lowers puberty hormones back to childhood levels.[2]

This surge then shutdown pattern is well established and is described on the FDA labels.

What the research shows

We keep animal and human evidence apart. A result in animals is a reason to study something in people, not proof that it works in people.

Animal and lab studies

Animal data matter mainly for pregnancy safety

  • In animal studies, triptorelin harmed developing young and caused pregnancy loss, which is why the label warns it can harm a fetus.[1]

Limit: The key evidence for this drug comes from human trials, not animals.

Human studies

Strong evidence that it shuts hormones down, none for restarting them

  • In prostate cancer trials with several hundred men, about 91% to 98% reached castration level testosterone by day 29, and most stayed there for months.[1]
  • Men in those trials most often reported hot flushes, in about 59% to 73%. Bone pain, headache, erectile problems and testicle shrinkage were also reported.[1]
  • In a 12 month study of 44 children with early puberty, 93% had LH lowered to prepuberty levels at month 6. Pain at the shot site occurred in 45%, and colds, headache and some early vaginal bleeding were also reported.[2]
  • PROMISE-GIM6 trial: 281 women before menopause with early breast cancer got chemotherapy alone or chemotherapy plus triptorelin shots. One year after chemotherapy, 8.9% versus 25.9% had gone into early menopause.[8]
  • Long term follow up of the same women: after 5 years, periods had returned in 72.6% with triptorelin versus 64.0% without, a difference that was not clearly real. After 12 years, survival free of cancer (65.7% versus 69.2%) and overall survival (81.2% versus 81.3%) were similar, so the shots did not appear to harm cancer outcomes.[10][11]
  • SOFT and TEXT trials: 4,690 women before menopause with hormone sensitive breast cancer had their ovaries switched off by triptorelin, surgery or radiation, plus one of two hormone pills. After 5 years, 91.1% on exemestane versus 87.3% on tamoxifen were free of cancer. Severe side effects occurred in about 30% in both groups.[9]
  • Some people hope the first hormone surge can restart their own testosterone after steroid use.[3] We found no controlled trial testing triptorelin for this, and a 2023 review of steroid recovery found that controlled data on recovery are scarce.[4]

Limit: Evidence for approved uses is strong, but use as a hormone restart rests on theory, not trials.

Claims check

The most common claims about this compound, and what studies actually found. Verdicts rate the evidence, not whether you should use it.

Restarts natural testosterone after a steroid cycle

Not tested

Some people hope the first hormone surge can restart their own testosterone after steroid use.[3] We found no controlled trial testing triptorelin for this, and a 2023 review of recovery after anabolic steroids found controlled data on recovery treatments are scarce.[4]

Boosts testosterone

No benefit in trials so far

Testosterone rises only briefly after the first dose. In prostate cancer trials with several hundred men, about 91% to 98% had testosterone pushed down to castration levels by day 29.[1]

Treats advanced prostate cancer

Shown in people

FDA approved Trelstar for advanced prostate cancer after trials showed that about 91% to 98% of men reached castration level testosterone by day 29, and most stayed there for months. Lowering testosterone slows this hormone fed cancer.[1]

Protects the ovaries during chemotherapy

Shown in people

In a randomized trial of 281 women with early breast cancer, early menopause one year after chemotherapy occurred in 8.9% of those also given triptorelin shots versus 25.9% with chemotherapy alone.[8] Whether this leads to more pregnancies is less clear: there were 8 versus 3 pregnancies, too few to be sure.[10]

Halts puberty that starts too early

Shown in people

In a 12 month study of 44 children with central precocious puberty, 93% had LH pushed down to prepuberty levels by month 6.[2]

Known risks and side effects

  • Can lower testosterone instead. Continued exposure shuts down LH, FSH and testosterone, which is the opposite of a restart. Hot flushes affected about 59% to 73% of men in prostate cancer trials.[1]
  • Metabolic and heart risks. Drugs in this class can raise blood sugar and blood fats. Heart attack, sudden cardiac death, stroke and heart rhythm changes have been reported.[1]
  • Seizures and mood changes. Seizures have been reported in adults and children. Children have had crying, irritability and aggression, and raised pressure around the brain.[1][2]
  • Allergic and skin reactions. Severe allergic reactions, swelling under the skin and serious skin reactions have been reported. Shot site pain affected 45% of children in the puberty study.[1][2]
  • Banned in sport. WADA bans GnRH analogs, including triptorelin, in male athletes. A 2023 study found a breakdown product in urine up to a month after a dose in some patients.[12][3]

Regulatory status

Today: Triptorelin is FDA approved and sold by prescription as Trelstar and Triptodur.[6][7] It does not appear on FDA's compounding category lists, and WADA prohibits it in male athletes.[13][12]

  1. FDA approved Trelstar for advanced prostate cancer.[6]
  2. WADA began listing GnRH analogs such as triptorelin as prohibited.[3]
  3. FDA approved Triptodur for central precocious puberty in children.[7]
  4. The Trelstar label was revised and lists warnings including tumor flare, high blood sugar, heart risks, seizures and serious skin reactions.[1]

Sources

  1. Verity Pharmaceuticals. TRELSTAR (triptorelin pamoate) prescribing information, revised June 2026. DailyMed. DailyMed
  2. Azurity Pharmaceuticals. TRIPTODUR (triptorelin) prescribing information, revised September 2025. DailyMed. DailyMed
  3. Saardpun N, Songsaeng R, Tanratana P, Kusamran T, Pinthong D. The Finding of New In Vivo Metabolite Triptorelin (5-10) in Human Urine Using Liquid Chromatography Coupled with Ion Trap/Time-of-Flight Mass Spectrometry with Dimethyl Sulfoxide Additives in the Mobile Phase. Molecules. 2023;28(12):4572. PMID 37375127
  4. Solanki P, Eu B, Smith J, Allan C, Lee K. Physical, psychological and biochemical recovery from anabolic steroid-induced hypogonadism: a scoping review. Endocr Connect. 2023;12(12):e230358. PMID 37855241
  5. FDA Global Substance Registration System. Triptorelin, UNII 9081Y98W2V. FDA GSRS
  6. US Food and Drug Administration. Drugs@FDA: TRELSTAR (triptorelin pamoate), NDA 020715. Drugs@FDA
  7. US Food and Drug Administration. Drugs@FDA: TRIPTODUR (triptorelin pamoate), NDA 208956. Drugs@FDA
  8. Del Mastro L, Boni L, Michelotti A, Gamucci T, Olmeo N, Gori S, et al. Effect of the gonadotropin-releasing hormone analogue triptorelin on the occurrence of chemotherapy-induced early menopause in premenopausal women with breast cancer: a randomized trial. JAMA. 2011;306(3):269-76. PMID 21771987
  9. Pagani O, Regan MM, Walley BA, Fleming GF, Colleoni M, Lang I, et al. Adjuvant exemestane with ovarian suppression in premenopausal breast cancer. N Engl J Med. 2014;371(2):107-18. PMID 24881463
  10. Lambertini M, Boni L, Michelotti A, Gamucci T, Scotto T, Gori S, et al. Ovarian Suppression With Triptorelin During Adjuvant Breast Cancer Chemotherapy and Long-term Ovarian Function, Pregnancies, and Disease-Free Survival: A Randomized Clinical Trial. JAMA. 2015;314(24):2632-40. PMID 26720025
  11. Lambertini M, Boni L, Michelotti A, Magnolfi E, Cogoni AA, Mosconi AM, et al. Long-Term Outcomes With Pharmacological Ovarian Suppression During Chemotherapy in Premenopausal Early Breast Cancer Patients. J Natl Cancer Inst. 2022;114(3):400-408. PMID 34850043
  12. World Anti-Doping Agency. The 2026 Prohibited List. WADA
  13. US Food and Drug Administration. Bulk Drug Substances Nominated for Use in Compounding Under Section 503A of the FD&C Act (category lists). Updated May 14, 2026. FDA category list
Medical disclaimer

This page is educational information only. It is not medical advice and does not replace care from a licensed medical provider. Do not use this page to decide whether to take any substance. Talk to a licensed medical provider first.

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