PeptidePeptideGnRH agonistOncology / reproductive pharmaceutical

Triptorelin

Also known as Trelstar · Decapeptyl · Triptodur

Written by enwyReviewed 15 Jul 20261 sources0 comments

Triptorelin is a long-acting GnRH agonist and an approved pharmaceutical used for prostate cancer, endometriosis, precocious puberty and other conditions. After an initial flare, continuous receptor stimulation profoundly suppresses LH, FSH and sex-hormone production (medical castration). In bodybuilding it is sometimes used off-label as a single-dose attempt to restart the axis after a cycle, a use with far less evidence than its licensed indications.

01 Overview

Triptorelin is a synthetic decapeptide GnRH agonist engineered for potency and durability. Clinically it is dosed as a depot to give sustained receptor occupation, which after a transient hormone surge (the flare) leads to downregulation and deep suppression of gonadotropins and sex steroids — the mechanism behind its use in hormone-sensitive prostate cancer and endometriosis.

The off-label bodybuilding rationale is essentially the opposite of chronic use: a single low subcutaneous dose is used to provoke a one-off LH/FSH surge to help restart a suppressed axis after anabolic steroid use. Evidence for this specific single-dose restart application is thin and largely anecdotal, in contrast to the strong clinical evidence for its licensed suppressive indications.

02 Mechanism

Potent GnRH agonist: an initial dose transiently stimulates LH/FSH (flare), while sustained exposure downregulates pituitary GnRH receptors and suppresses gonadotropin and sex-steroid output.

03 Dosing

Tier	Dose	Route	Notes
Off-label restart	100 mcg	SubQ	Off-label single-dose axis-restart use (~100 mcg one-off). Licensed oncology use is depot dosing in mg every 1-6 months.

04 Effects

Effect	Magnitude	Evidence
Transient LH/FSH surge (flare)A single dose produces an initial gonadotropin and testosterone surge before suppression, the basis of off-label restart use.	Sharp initial rise	Clinical
Sustained sex-hormone suppression (chronic use)Continuous dosing suppresses LH/FSH and sex steroids — therapeutic in cancer but the opposite of the bodybuilding goal.	Castrate-level suppression	Clinical

05 Side effects

Effect	Severity	Frequency	Evidence	Countermeasures
Hormone flare on initiationInitial testosterone/oestrogen surge can transiently worsen hormone-sensitive conditions.	Moderate	Expected	Clinical
Hypogonadal symptoms with continued useHot flushes, low libido, bone loss and mood effects from suppressed sex hormones.	Moderate	With chronic dosing	Clinical

06 Legal status

United States

FDA-approved prescription drug

Approved for prostate cancer and other indications; off-label axis-restart use is unlicensed. · as of Jan 2026

07 References

Triptorelin: pharmacology and clinical use as a GnRH agonistDrugs / oncology reviews

08 Discussion0 comments

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This page is reference information, not medical advice. Doses and protocols are documented as they appear in the clinical literature and in practice — describing them is not a recommendation to use them. Countermeasures listed here are not a substitute for a physician. Legal status varies by jurisdiction and changes.