Trelstar / Triptodur (triptorelin)

An FDA-approved shot for advanced prostate cancer (Trelstar) and puberty that starts too early in kids (Triptodur). A "testosterone restart" is not an approved use.

AI illustration of a vial labeled Triptorelin — AI illustration

FDA statusFDA approved

Approved in the US for advanced prostate cancer (Trelstar) and early puberty in children (Triptodur).

Proof it works in people for its approved uses (prostate cancer, early puberty)Strong

Several large trials for its approved uses.

Safety data in peopleWell studied

Years of use. Risks are on the FDA label.

Three separate grades: the law (approved for 2 uses), proof (strong for those uses), and safety data (well known). None of it covers a "testosterone restart."

By the Peptide Science Desk Editorial TeamFact-checked against FDA and official sources · Oct 28, 2026Not yet reviewed by a licensed clinician. How we check facts

What is it?

Triptorelin is a lab-made copy of GnRH, with one building block swapped so it lasts much longer. That is the trick: GnRH normally comes in pulses. A steady, long-lasting signal makes the pituitary stop answering, so sex hormones drop. The brands are Trelstar and Triptodur.

Why do people use it?

Trelstar lowers testosterone to slow advanced prostate cancer. Triptodur pauses puberty that starts too early in children 2 and older. Online, some men take one shot hoping to "restart" testosterone after steroids. That is not an approved use.

Does it really work?

Yes, for prostate cancer and early puberty. In a 284-man trial, it kept testosterone down as well as leuprolide. In children, puberty hormones stayed down for a year in nearly all. A breast cancer trial found fewer cases of early menopause, but that is not a US-labeled use.

Studies in people

We found 5 trials in people. None tested a "testosterone restart" in men.

Study design	People	What they measured	What they found	Year	Journal	PubMed
Randomized trial vs leuprolide	284 men with advanced prostate cancer	Testosterone kept at castration level	Worked as well as leuprolide. 9-month survival 97.0% vs 90.5%.	2003	BJU Int	PMID 12887472
Single-group trial, long-acting shot	120 men with prostate cancer	Testosterone suppression for 12 months	97.5% reached castration level by day 29. Hot flushes in 71.7%.	2009	Clin Drug Investig	PMID 19888782
Single-group trial	44 children with early puberty	Puberty hormone (LH) suppression	93.2% suppressed at month 6, and it held through month 12.	2016	J Pediatr Endocrinol Metab	PMID 26887034
Single-group trial (phase 3, China)	66 children with early puberty	LH suppression and side effects	100% suppressed at month 6, and 98.5% at month 12.	2024	Adv Ther	PMID 39412628
Randomized trial (not a US-labeled use)	281 women with breast cancer on chemo	Early menopause	Early menopause in 8.9% with triptorelin vs 25.9% without.	2011	JAMA	PMID 21771987

Official labels

We read each of these 5 papers on PubMed on October 28, 2026.

Is it safe? Side effects

Trelstar’s label: hot flashes are very common. Bone pain, erection problems and headache also happen.
When it starts, hormones rise for a short time ("flare"), which can make cancer symptoms worse at first.
Triptodur’s label lists shot-site reactions, vaginal bleeding, hot flashes and headache. It also warns about mood changes and seizures.
The Trelstar label also warns of higher blood sugar, heart problems and seizures with this type of drug.

Is it legal in the US?

Yes. Trelstar and Triptodur are FDA-approved for their labeled uses. Using triptorelin for a "testosterone restart" or bodybuilding is not an approved use.

What this means for Trelstar / Triptodur

A doctor may prescribe it off-label, but no trial supports a "testosterone restart." (FDA)
Copies sold online "for research" are not Trelstar or Triptodur. (FDA)
Bringing unapproved copies into the US for yourself is, in most cases, illegal, the FDA says. (FDA)

Banned in sports? Drug tests

Banned for male athletes.

Yes, for men. WADA bans triptorelin at all times for male athletes (section S2.2.1: peptides that raise testosterone in males). Women athletes should still check with USADA.

Check work, NCAA, and military rules for Trelstar / Triptodur

Talk to your doctor

If your testosterone is low after steroids, ask a hormone doctor (endocrinologist) for a plan. A drug built to shut hormones down is a risky way to try to turn them on. We never share doses or tell you where to buy. Print our doctor questions sheet.

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Not medical advice. Medical disclaimer.