--- title: "GnRH Analogue Injections Guide | The Gender Hormone Clinic" description: "Prostap, Decapeptyl and Zoladex: long-acting injectable blockers that suppress testosterone at the source, given every 4–12 weeks." url: https://thegenderhormoneclinic.com/patient-resources/medication-guides/gnrh-analogue-injections/ --- [Home](https://thegenderhormoneclinic.com/) / [Medication guides](https://thegenderhormoneclinic.com/patient-resources/medication-guides/) / GnRH Analogue Injections TRANS-FEMININE HRT · MEDICATION GUIDE # GnRH Analogue Injections therapy, a clear guide. GnRH analogues are the most effective testosterone blockers we prescribe. Rather than blocking the receptor, they switch off the pituitary signal that tells the testes to make testosterone, giving very low and very stable levels. Prostap can be self-administered at home after a one-off training session and signed consent; Decapeptyl and Zoladex are clinician-administered. [Begin your journey](https://thegenderhormoneclinic.com/make-an-enquiry/) [See payment plans](https://thegenderhormoneclinic.com/patient-resources/payment-plans/) Drug class GnRH analogue Route SC (Prostap) / IM (Decapeptyl) / SC implant (Zoladex) Frequency Every 4-12 weeks Administration Prostap self-admin possible; Decapeptyl and Zoladex clinician-only Effect Very low testosterone Reversible Fully, on stopping On this page[Overview](#ma-overview)[How it works](#ma-how-it-works)[Side effects](#ma-side-effects)[Cost](#ma-cost)[FAQ](#ma-faq) OVERVIEW ## What gnrh analogue injections does, in plain English. Prostap (leuprorelin), Decapeptyl (triptorelin) and Zoladex (goserelin) are the GnRH analogues used in UK gender care. All three work the same way: continuous stimulation of the pituitary paradoxically shuts down its release of the hormones (LH and FSH) that drive testosterone production. The result is testosterone suppressed to very low levels, which lets a lower, safer oestrogen dose do the feminising work. Prostap is our most commonly prescribed option, given as a subcutaneous depot injection, typically 11.25 mg every 12 weeks (a 3.75 mg 4-weekly form also exists). Patients can be trained to self-administer Prostap at home after a one-off training session and signed consent. Decapeptyl is an intramuscular injection, 11.25 mg every 12 weeks (a 3 mg monthly form also exists) and is clinician-administered. Zoladex is a small depot implant placed under the skin of the abdomen, 10.8 mg every 12 weeks, also clinician-administered. HOW IT WORKS ## The way it actually works. For the first week or two a GnRH analogue actually stimulates testosterone (the "flare") before it downregulates the pituitary and suppression sets in. We plan around that, sometimes overlapping an oral blocker over the first cycle. From then on, levels stay low and stable until the next dose is due. Acts at the pituitary Shuts down the LH/FSH signal that drives the testes, so production falls at the source. Very stable levels One dose covers weeks: no daily tablet, and none of the peaks and troughs. Plan for the flare A brief early testosterone rise is expected and managed, often with a short oral-blocker overlap. Fully reversible Production resumes once you stop; the effect is not permanent. SIDE EFFECTS & RISKS ## What to watch for, and what to tell us. GnRH analogues have a favourable safety profile and are well tolerated. Most effects come from low testosterone itself and are shared with the other blockers; a couple are specific to the injection or implant. Common Lower libido and erections + Expected with strong testosterone suppression. Hot flushes + Especially early, before oestrogen is fully established. They settle as oestrogen builds. Injection / implant-site reactions + Soreness, bruising or a small lump at the site for a few days. Fatigue or mood dips + Some patients feel flatter around the changeover; tell us if it persists. Less common / serious Testosterone flare + A brief rise in the first 1-2 weeks before suppression. Planned for, and rarely a problem in practice. Bone density + Prolonged very-low sex-hormone levels can thin bone, but adequate oestrogen protects against this, which is why the two are prescribed together. Monitoring schedule We catch things early. Here's the routine you can expect. Most of the testing is front-loaded while we fine-tune your dose. Once your levels are stable, it's usually just once a year. Baseline Testosterone & oestradiol FBC, U&E, LFTs Blood pressure 3–6 months Testosterone (suppression) Oestradiol level 6-monthly while adjusting Testosterone & oestradiol LFTs Yearly once stable Full hormone panel Symptom & dose review COST ## What gnrh analogue injections costs you, monthly. GnRH analogues cost more than oral blockers privately, but only four doses a year are needed. Once your GP prescribes under shared care, the cost drops to the standard NHS prescription charge. The figures below are approximate; confirm with your pharmacy. Prostap (private) ~£70-90 per 12 weeks Leuprorelin 11.25 mg Decapeptyl (private) ~£70-90 per 12 weeks Triptorelin 11.25 mg Zoladex (private) ~£80-100 per 12 weeks Goserelin 10.8 mg implant Once on shared care £9.90 per item Standard NHS Rx charge [See full payment plan](https://thegenderhormoneclinic.com/patient-resources/payment-plans/) FREQUENTLY ASKED ## Questions, answered. This guide isn't a substitute for clinical advice. We'll talk you through everything at your appointment. [Make an enquiry](https://thegenderhormoneclinic.com/make-an-enquiry/) ## Ready to take the first step? Send us an enquiry and we'll be in touch within two working days. [Make an enquiry](https://thegenderhormoneclinic.com/make-an-enquiry/)