Triptorelin is a synthetic decapeptide and one of the most widely prescribed gonadotropin-releasing hormone (GnRH) agonists in the world. Sold as Trelstar, Triptodur, and Decapeptyl, it works by shutting down the body's own sex-hormone production, which makes it a cornerstone treatment for advanced prostate cancer, endometriosis, uterine fibroids, central precocious puberty, hormone-receptor-positive breast cancer, and certain fertility protocols. This guide explains what triptorelin is, how it works, the exact doses used for each condition, what the clinical data show, and the safety trade-offs that matter most, with a focus on its role in endometriosis and reproductive medicine.
🔑 Key Takeaways
- Triptorelin is a long-acting GnRH agonist that suppresses LH and FSH, producing a temporary, reversible "medical castration" or menopause-like state.
- It is FDA-approved in the US as Trelstar for advanced prostate cancer and as Triptodur for central precocious puberty; Decapeptyl is the global brand used for endometriosis, fibroids, IVF, and breast cancer.
- For endometriosis, monthly triptorelin 3.75 mg (3,750 mcg) cut pelvic pain in 74.4% of women and dysmenorrhea in 83.6% after conservative surgery.
- Treatment causes a brief hormone "flare" in the first 1 to 2 weeks, then deep suppression; hot flushes and bone-density loss are the main trade-offs, which add-back therapy can blunt.
- Triptorelin is contraindicated in pregnancy and is not a research peptide you self-administer; it is a prescription depot injection given by a clinician.
What Is Triptorelin?
Triptorelin is a synthetic analog of gonadotropin-releasing hormone (GnRH, also called LHRH). It is a decapeptide, meaning it is built from ten amino acids, and it differs from natural GnRH by a single substitution that makes it far more potent and longer-lasting.[8] Because it is broken down by digestive enzymes if swallowed, triptorelin is delivered as a long-acting depot injection that slowly releases drug over weeks to months.
It belongs to the same drug class as buserelin, leuprolide (Lupron), and goserelin. If you have read our guide to the GnRH agonist buserelin, the mechanism here is nearly identical, just with a different molecule and dosing schedule. Triptorelin should not be confused with gonadorelin, which is synthetic GnRH itself used in short, pulsed doses to stimulate hormone output rather than suppress it.
How Triptorelin Works: The "Flare Then Suppress" Mechanism
Natural GnRH is released by the hypothalamus in short pulses, which tells the pituitary to secrete luteinizing hormone (LH) and follicle-stimulating hormone (FSH). Those gonadotropins then drive the testes to make testosterone and the ovaries to make estrogen.
Triptorelin floods the GnRH receptor with a constant, non-pulsatile signal. At first this causes a transient surge in LH, FSH, and sex hormones, the so-called "flare." Within about 1 to 4 weeks the pituitary receptors become desensitized and downregulated, gonadotropin output collapses, and sex-hormone levels fall to castrate (in men) or postmenopausal (in women) ranges.[1]
In men treated with Trelstar 3.75 mg, castrate testosterone levels (50 ng/dL or lower) were reached by Day 29 in 91.2% of patients and maintained through roughly 8 months in over 93%.[1] In women undergoing IVF or treated for endometriosis, the same molecule drives estradiol down to menopausal levels, with over 98% of endometriosis patients chemically suppressed by week 12.[5]
Why the initial flare matters
In advanced prostate cancer, the early testosterone surge can briefly worsen symptoms (bone pain, urinary obstruction), so oncologists often co-prescribe an anti-androgen for the first few weeks to cover the flare. In endometriosis and fibroids, the flare can cause a short pre-treatment increase in symptoms or bleeding before suppression takes hold.[1]
Approved Uses and Brand Names
Triptorelin is one drug sold under several brand names, with the indication tied to the formulation and country.
| Brand | Region / approval | Primary use | Typical depot dose |
|---|---|---|---|
| Trelstar | US (FDA) | Advanced prostate cancer | 3.75 mg / 4 wk, 11.25 mg / 12 wk, 22.5 mg / 24 wk |
| Triptodur | US (FDA, 2017) | Central precocious puberty | 22.5 mg every 24 weeks |
| Decapeptyl | Europe / global | Endometriosis, fibroids, breast cancer, IVF | 3.75 mg / 4 wk (depot); 0.1 mg daily (short form) |
Advanced Prostate Cancer
This is triptorelin's flagship FDA indication. By dropping testosterone to castrate levels, it slows hormone-sensitive prostate tumors. The depot is given intramuscularly into the buttock, with three interchangeable schedules (monthly, quarterly, or twice yearly) so patients can match dosing to their treatment plan.[1]
Endometriosis and Adenomyosis
Endometriosis is estrogen-dependent, so cutting estrogen production starves the ectopic tissue and shrinks lesions. This is the use behind the high-volume "triptorelin for endometriosis" searches, and the data are strong (see the dedicated section below). Triptorelin is also used off-label and in observational studies for adenomyosis and uterine fibroids before surgery.
Central Precocious Puberty (CPP)
Triptodur was FDA-approved in July 2017 as the first twice-yearly GnRH agonist for children aged 2 and older with central precocious puberty.[3] By suppressing the premature pubertal hormone signal, it halts early sexual development and protects final adult height. In trials, Triptodur returned LH to prepubertal levels in 93% of children, with 98% maintaining suppression at 12 months.[3]
Hormone-Receptor-Positive Breast Cancer
In premenopausal women, triptorelin induces ovarian function suppression and is used alongside tamoxifen or an aromatase inhibitor as a standard-of-care adjuvant treatment for HR-positive breast cancer.[8] Separately, the PROMISE-GIM6 randomized trial showed that giving triptorelin during chemotherapy reduced chemotherapy-induced early menopause, supporting its use for ovarian (fertility) protection.[7]
Assisted Reproduction (IVF)
This is the one setting where triptorelin is used at tiny doses to trigger rather than suppress. A single subcutaneous bolus of about 0.2 mg (200 mcg) of triptorelin can replace hCG to trigger the final egg-maturation LH surge in GnRH-antagonist IVF cycles, which substantially lowers the risk of ovarian hyperstimulation syndrome (OHSS) in high responders.[6] Egg retrieval is typically performed 36 hours after the trigger. This is conceptually similar to how hCG and the master upstream hormone kisspeptin are used in fertility medicine.
Triptorelin for Endometriosis: What the Data Show
For women searching specifically for triptorelin and endometriosis, here is the evidence. The standard regimen is intramuscular triptorelin 3.75 mg (3,750 mcg) once every 28 days, usually for up to 6 doses (24 weeks), often started after conservative laparoscopic surgery to prevent recurrence.
In a multicenter prospective study of 384 women (mean age 33) with deep infiltrating endometriosis who received triptorelin 3.75 mg monthly after surgery, the 24-month cumulative improvement rates were:[4]
| Symptom | Improvement rate | Patients |
|---|---|---|
| Dysmenorrhea (painful periods) | 83.6% | 270 of 323 |
| Pelvic pain | 74.4% | 166 of 223 |
| Dyspareunia (pain with sex) | 66.9% | 109 of 163 |
The 24-month symptom-recurrence rate was 22.2%, and the regimen was well tolerated with no serious adverse events.[4] A separate Phase 3 randomized controlled trial in China comparing two triptorelin formulations confirmed both were equally effective at reducing endometriosis-associated pelvic pain, with over 98% of patients chemically suppressed by week 12.[5]
The bone-density trade-off and add-back therapy
Because triptorelin lowers estrogen, prolonged use (beyond about 6 months) accelerates bone-mineral-density loss, the same concern seen in breast-cancer ovarian suppression studies.[8] To extend treatment safely, clinicians often add "add-back therapy" (low-dose estrogen plus a progestin, or norethindrone). One add-back study cut endometriosis symptom scores from 7.4 to 2.5 at 3 months with minimal bone loss. Add-back lets patients keep the pain relief while protecting the skeleton.
Triptorelin Dosage by Indication
All doses below are prescription depot injections given by a clinician. Triptorelin is not a self-administered research peptide, and doses must not be improvised. Metric and US-equivalent units are shown where relevant.
| Condition | Dose | Schedule | Route |
|---|---|---|---|
| Advanced prostate cancer | 3.75 mg (3,750 mcg) | Every 4 weeks | Intramuscular |
| Advanced prostate cancer | 11.25 mg (11,250 mcg) | Every 12 weeks | Intramuscular |
| Advanced prostate cancer | 22.5 mg (22,500 mcg) | Every 24 weeks | Intramuscular |
| Central precocious puberty (Triptodur) | 22.5 mg (22,500 mcg) | Every 24 weeks | Intramuscular |
| Endometriosis / fibroids | 3.75 mg (3,750 mcg) | Every 4 weeks, up to 6 doses | Intramuscular |
| IVF agonist trigger | ~0.2 mg (200 mcg) | Single dose | Subcutaneous |
Side Effects and Safety
Most side effects are predictable consequences of low sex hormones, essentially a temporary menopause or andropause. In men on Trelstar, the most common adverse reactions were hot flushes (58.6% to 73%), skeletal pain (12% to 13%), erectile dysfunction or impotence (7% to 10%), headache, leg edema, and testicular atrophy.[1] In women, expect hot flushes, vaginal dryness, mood changes, reduced libido, and, with prolonged use, bone-density loss.
Across larger safety datasets, the recognized risk profile of triptorelin and the GnRH-agonist class includes injection-site reactions, mood disturbance, the initial tumor or symptom flare, and accelerated bone loss with extended use.[8] Like other agents in this category, label updates over time have flagged cardiovascular and metabolic monitoring in long-term androgen-deprivation therapy.
Who should not use triptorelin
Triptorelin is contraindicated in anyone with hypersensitivity to triptorelin, other GnRH agonists, or GnRH itself.[1] It must not be used in pregnancy, as it can harm a developing fetus, and women of reproductive age should use non-hormonal contraception during treatment. It is not appropriate for casual or cosmetic use.
How Triptorelin Compares to Other Hormone Peptides
Triptorelin sits at the suppressive end of the hormone-axis spectrum. Understanding where it fits helps clarify why it is so different from the stimulating peptides covered elsewhere on PeptideDeck.
| Peptide | Class | Net effect on sex hormones | Typical goal |
|---|---|---|---|
| Triptorelin | GnRH agonist (depot) | Suppress (after brief flare) | Shrink hormone-driven disease |
| Buserelin | GnRH agonist | Suppress (after brief flare) | Endometriosis, IVF, prostate cancer |
| Gonadorelin | GnRH (pulsatile) | Stimulate | Maintain testicular function on TRT |
| hCG | LH mimic | Stimulate | Fertility, testosterone support |
| Kisspeptin | Upstream GnRH driver | Stimulate | Fertility research, IVF trigger |
For context on the stimulating side of this axis and how clinicians keep the gonads working during testosterone therapy, see our guides to gonadorelin versus hCG and enclomiphene. If you are exploring GLP-1 medications and reproductive health (a common overlap), our GLP-1 for PCOS guide covers fertility considerations in that context.
Cost of Triptorelin
Triptorelin is an expensive specialty injection, and price varies sharply by brand, dose, and insurance. These are list-price ranges and most patients pay far less with insurance or manufacturer copay programs.
| Product / dose | Approximate cash list price | Notes |
|---|---|---|
| Trelstar 3.75 mg (monthly) | ~$945 per injection | Prostate cancer; covers ~1 month[9] |
| Trelstar 11.25 mg (quarterly) | ~$2,820 per injection | Covers ~3 months[9] |
| Triptodur 22.5 mg (twice yearly) | ~$22,400 per injection | Pediatric CPP; copay programs can cut cost to as little as $5[10] |
Because triptorelin is administered and often billed as a medical (buy-and-bill) procedure rather than a pharmacy prescription, many patients never see the full list price. Manufacturer copay assistance and oncology patient-assistance programs are widely available.[10]
Frequently Asked Questions
The Bottom Line
Triptorelin is a well-established, evidence-backed GnRH agonist that works by switching off the body's sex-hormone production. That single mechanism makes it valuable across prostate cancer, endometriosis, fibroids, precocious puberty, breast cancer, and IVF. For endometriosis specifically, monthly 3.75 mg triptorelin delivers meaningful, well-documented pain relief, with the main caveats being the initial flare and bone-density loss that add-back therapy can manage. It is a prescription depot medication, not a consumer peptide, and every use should be supervised by a physician.
References
- DailyMed. Trelstar (triptorelin pamoate) Prescribing Information, U.S. National Library of Medicine.
- U.S. FDA. Trelstar (triptorelin) Full Prescribing Information, accessdata.fda.gov.
- Healio. FDA approves extended-release triptorelin (Triptodur) for central precocious puberty, 2017.
- Efficacy and safety of triptorelin therapy following conservative surgery for deep infiltrating endometriosis: a multicenter prospective study (n=384). Medicine (Baltimore), 2022. PMC8812645.
- Assessment of Two Formulations of Triptorelin in Chinese Patients with Endometriosis: A Phase 3 Randomized Controlled Trial. Advances in Therapy, 2022.
- Use of a single bolus of GnRH agonist triptorelin to trigger ovulation in GnRH-antagonist IVF cycles. Human Reproduction, 2000. PMID 10966996.
- Lambertini M, et al. Ovarian Suppression With Triptorelin During Adjuvant Breast Cancer Chemotherapy and Long-term Ovarian Function (PROMISE-GIM6). JAMA, 2015. PMID 26242299.
- Evaluating triptorelin as a treatment option for breast cancer. Expert Opinion on Pharmacotherapy, 2019. PMID 31500470.
- GoodRx. Trelstar (triptorelin) Prices, Coupons and Savings Tips.
- Drugs.com. Triptodur (triptorelin) Prices, Coupons and Patient Assistance.