Triptorelin
GnRH AgonistapprovedAlso known as: Trelstar, Decapeptyl, Gonapeptyl, GnRH Agonist
A synthetic GnRH agonist decapeptide used medically for prostate cancer, endometriosis, and off-label for PCT (post-cycle therapy) to restart the hypothalamic-pituitary-gonadal axis after anabolic steroid use.
Overview
Triptorelin is a synthetic analogue of gonadotropin-releasing hormone (GnRH) that is approximately 100 times more potent than natural GnRH. It is a decapeptide with a substitution at position 6 (D-Trp) that increases its resistance to enzymatic degradation. In medical settings, triptorelin is used as a sustained-release formulation for prostate cancer, precocious puberty, endometriosis, and uterine fibroids. In the bodybuilding and performance enhancement community, a single low-dose injection of triptorelin has gained popularity as a 'PCT reset' — a way to rapidly restart natural testosterone production after prolonged suppression from anabolic steroids. The initial surge of LH and FSH it produces can jumpstart the HPG axis, though this use remains controversial and carries significant risks if dosed incorrectly.
Mechanism of Action
Triptorelin binds to GnRH receptors in the anterior pituitary with high affinity. Initially, it causes a dramatic surge ('flare') of LH and FSH release, which in turn stimulates testosterone (or estrogen) production. With continuous administration, it paradoxically downregulates and desensitizes GnRH receptors, leading to a profound suppression of gonadotropins and sex hormones (chemical castration). This biphasic response is key: a single dose produces the stimulatory flare (useful for PCT), while sustained dosing produces suppression (useful for hormone-sensitive cancers). The D-Trp6 substitution prevents rapid degradation by endopeptidases, extending its half-life significantly compared to native GnRH.
Molecular Formula
C64H82N18O13
Molecular Weight
1311.5 g/mol
Sequence
pGlu-His-Trp-Ser-Tyr-D-Trp-Leu-Arg-Pro-Gly-NH2
Dosage Protocols
Dose Range
50mcg – 100mcg
Frequency
Single injection
Route
intramuscular
Cycle Length
One-time use
A single low-dose injection to trigger LH/FSH flare and restart natural testosterone production. DO NOT repeat — additional doses risk chemical castration through receptor downregulation. Wait 1-2 weeks after last steroid injection before administering.
Source: Community PCT protocols
🧮 Personalized Dosage Calculator
💰 Estimated Pricing
Typical Supply
3.75mg or 11.25mg depot
Last Updated
2026-02
Brand Trelstar. GnRH agonist for prostate cancer, endometriosis, precocious puberty. Monthly or 3-month depot. Insurance usually covers.
⚠️ Prices are estimates based on publicly available data and may vary significantly by vendor, location, and prescription status. This is not medical or financial advice.
Side Effects
| Effect | Severity |
|---|---|
| Hot flashes | mild |
| Temporary testosterone suppression | severe |
| Injection site pain | mild |
| Mood changes | moderate |
| Headache | mild |
Pros & Cons
Can rapidly restart HPG axis with a single injection, making it one of the fastest PCT options available
FDA-approved drug with well-characterized pharmacology and decades of clinical use
Only requires one dose for PCT purposes — no multi-week protocol needed
Extremely narrow dosing window — overdosing causes the opposite of the desired effect (chemical castration)
Not intended or studied for PCT use; this application is entirely off-label
Risk of prolonged hypogonadism if used incorrectly
Initial flare can temporarily worsen hormone-sensitive conditions
Research Studies
🩸 Blood Work
Total Testosterone
GnRH agonist — causes initial surge then suppression of testosterone
Free Testosterone
Monitor testosterone changes through flare and suppression
LH (Luteinizing Hormone)
Monitor gonadotropin axis response
FSH (Follicle-Stimulating Hormone)
Assess HPG axis status
Estradiol (E2)
Estrogen monitoring during hormonal changes
PSA (if male, >40)
Prostate monitoring with testosterone changes
Potent GnRH agonist — single dose used for PCT (post-cycle therapy) to restart HPTA. Causes initial testosterone flare before suppression (with continuous use). Hormone panel essential to assess recovery.
Legal Status
FDA-approved as Trelstar for prostate cancer. Prescription-only medication. Available as a research chemical. Banned by WADA.
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