Triptorelin (GnRH)

Key points

• Triptorelin is a GnRH agonist, a modified copy of the brain's fertility signal.
• Given steadily, it first stimulates then switches off the release of sex hormones, which is used to treat several conditions.
• It is a licensed, prescription only medicine in the UK, for example for prostate cancer, endometriosis, fibroids and early puberty.
• It is sometimes misused in bodybuilding to restart hormones, which is off the licensed use and not advisable without supervision.

Quick facts

What it is

GnRH agonist, a licensed medicine

Licensed use

Prostate cancer, endometriosis, fibroids, early puberty

UK status

Licensed, prescription only medicine

How it acts

Steady use lowers sex hormones

How it works

A short burst of GnRH signalling raises sex hormones, but constant signalling does the opposite: the pituitary stops responding, and sex hormone production falls. Triptorelin uses this to lower testosterone in prostate cancer or oestrogen in endometriosis. A single pulse can also briefly stimulate hormone release, which is the basis of its misuse to kick start the body's own production.

What the evidence shows

Triptorelin is well established in its licensed uses, backed by trials in prostate cancer, endometriosis and other conditions. Its use in bodybuilding to restart natural hormones rests on little controlled evidence and can backfire if used wrongly.

What it does not settle

• There is little controlled evidence for off licence bodybuilding use.
• The timing and dose for such use are not well established.
• Self directed use can disrupt hormones rather than help.

Side effects

Common

• Effects of low sex hormones, such as hot flushes, reduced libido, tiredness and mood changes.
• Injection site reactions, and a temporary flare of symptoms when starting.

Less common but serious

• Longer term, lowering sex hormones can affect bone density, which is managed in licensed treatment.
• Products from unregulated sellers are of unverified quality, and misuse can seriously disrupt hormone balance.

Report any suspected side effect through the MHRA Yellow Card scheme.

UK legal status and access

Triptorelin is a licensed prescription only medicine in the UK, prescribed and monitored by a specialist for its approved conditions. Material sold online for other purposes is unlicensed and of unverified quality.

Common questions