Gonadorelin is a lab-made copy of gonadotropin-releasing hormone (GnRH), the 10-amino-acid signal from the brain that tells the pituitary gland to release LH and FSH.[5][4] In the US, it was approved as Factrel in 1982 and as the Lutrepulse kit in 1989, but both are now discontinued.[1][2] Given in pulses by pump, it can restore ovulation and sperm production in people whose brain makes too little GnRH.[9][12] Today it is also compounded for men on testosterone therapy (TRT), a use with very little trial evidence.[15]
This profile covers what gonadorelin is, what the research shows, use with TRT, dosage, side effects, how it compares with hCG and kisspeptin, and its legal status.
What is gonadorelin?
Gonadorelin has the same amino acid sequence as natural GnRH.[5] The pituitary responds to it by releasing LH and FSH, which in turn drive the testes or ovaries.[4]
Its US history:
- Factrel (1982): an injection labeled for evaluating hypothalamic-pituitary gonadotropic function, in vials of 100 to 500 micrograms.[1][3]
- Lutrepulse kit (1989): gonadorelin acetate from Ferring.[2] Ferring later ran a Phase 3 trial of LutrePulse delivered by an OmniPod pump.[11]
- Today: Drugs@FDA lists both human products as discontinued.[1][2] In the UK, a 100-microgram gonadorelin injection is listed as a pituitary function test.[4]
Gonadorelin remains widely used in animals. Factrel for cattle, for example, is approved to treat ovarian cysts and to time ovulation for artificial insemination, and its label says it is not for human use.[5]
Because it acts on reproductive hormones, gonadorelin belongs to our hormonal and sexual health categories.
Why the delivery pattern matters
GnRH is cleared in minutes. A 1978 study in 6 volunteers measured a half-life of 2.4 minutes after an IV injection.[6] The UK label gives about 4 minutes.[4]
Timing changes the effect. In a classic 1978 monkey study, hourly pulses of GnRH restored LH and FSH release, while a constant infusion failed to and could switch the pituitary off.[7] Continuous exposure leads to this down-regulation, so gonadorelin only works as intended when it mimics the body’s natural pulses.[15]
Gonadorelin benefits: what the research shows
Almost all the strong evidence comes from pulsatile pump treatment in people whose own GnRH is missing.
Women with hypothalamic amenorrhea
- 2018 meta-analysis: 35 studies with 1,002 women. Pulsatile GnRH achieved high ovulation rates, injected under the skin worked about as well as into a vein, OHSS was rare and mild, and multiple pregnancies were only slightly more common than in the general population.[9]
- Swiss 25-year cohort: 66 women with functional hypothalamic amenorrhea had ovulation in 96% of cycles, usually from a single follicle, and 65.9% of treatments ended in a live birth. Two authors consult for Ferring.[10]
- LutrePulse Phase 3 (Ferring): in 39 women with primary amenorrhea, 9 of 18 on 15 or 20 micrograms per pulse ovulated, versus 0 of 10 on placebo.[11]
- Russian experience: a 1995 Russian study gave a GnRH product (Lutrelef) by pulse pump for ovulation induction. It worked, but did not clearly beat hMG.[14]
Men with hypogonadotropic hypogonadism
- 1982 NEJM case series: pump-delivered GnRH raised testosterone in 6 men from 77 to 520 ng/dL within a month, and 3 produced sperm by 43 weeks.[8]
- 2021 meta-analysis: in 420 men, GnRH pumps gave larger testes and sperm about 5 months sooner than hCG plus hMG-type gonadotropin therapy, with similar sperm and pregnancy rates.[12]
- Chinese study: after 6 months of pulsatile gonadorelin, 22 young men had better bone density and lower insulin resistance.[13]
Gonadorelin with TRT
Testosterone therapy shuts down LH and FSH, which can shrink the testes and lower sperm counts.[15] hCG was the usual add-on. But on March 23, 2020, hCG moved to being regulated as a biologic, and FDA said such products lost their compounding exemptions.[16] One online reviewer said they switched to gonadorelin because hCG was unavailable.[22]
The problem is the half-life. A single injection produces a brief LH pulse that is gone within minutes,[6] while the evidence for gonadorelin comes from pumps that deliver frequent pulses around the clock.[8][10] We found no controlled trials of once-daily or twice-weekly gonadorelin injections in men on TRT, so there is no proof that they preserve testicular size or fertility.
Gonadorelin dosage
| Use | Dose |
|---|---|
| Pituitary function test (UK label) | 100 micrograms once, under the skin or into a vein[4] |
| Pump treatment (LutrePulse trial) | 10, 15 or 20 micrograms per pulse under the skin[11] |
| Use with TRT | No approved or trial-tested dose |
Doses used by TRT clinics are not based on published trials. If you are working out how many micrograms are in a compounded vial, our peptide calculator can help, but your prescriber should set the dose.
Gonadorelin side effects
The UK label lists these side effects, most of them as rare:[4]
- Fast heartbeat, flushing, headache and dizziness (rare)
- Nausea and abdominal discomfort (rare)
- Hardening at the injection site (rare); pain and swelling (uncommon)
- Allergic reactions, including bronchospasm and hives (rare), itching (uncommon) and rash, plus antibody formation
Other cautions: GnRH drugs are not advised in people with a pituitary adenoma because of the risk of bleeding into the tumor (pituitary apoplexy), and the label lists pregnancy as a contraindication.[4] With pump treatment, allergic reactions were more common than with gonadotropins,[12] and IV pumps rarely caused vein inflammation.[9]
Gonadorelin vs hCG and kisspeptin
| Gonadorelin | hCG | Kisspeptin-10 | |
|---|---|---|---|
| Acts on | Pituitary (GnRH receptor)[4] | Testes or ovaries directly, like LH | Brain, upstream of GnRH |
| Status | US human products discontinued[1] | Approved biologic | Experimental |
hCG skips the pituitary entirely. Kisspeptin-10 works one step higher, triggering the brain’s own GnRH release. hMG supplies FSH and LH activity directly for fertility treatment.
Is gonadorelin legal?
- No current US human product: Factrel and Lutrepulse are discontinued.[1][2] Veterinary gonadorelin is not for human use.[5]
- Compounding: gonadorelin is not on FDA’s 503A nomination list.[18] Federal law lets 503A pharmacies compound from a bulk substance that meets a USP monograph where one exists, is a component of an FDA-approved drug, or appears on FDA’s 503A bulks list.[19] FDA’s separate 503B nominations list marks gonadorelin acetate as a component of an FDA-approved drug and places it in Category 1, under evaluation.[17] In our reading, gonadorelin can still be compounded under 503A because it is an ingredient of FDA-approved drugs (or under a USP monograph, if one applies), even though those drugs are discontinued. That is our interpretation, not an FDA statement, and we did not confirm whether a current USP monograph exists. A University of Maryland (M-CERSI) team reviewed gonadorelin acetate in 2021 for FDA’s 503B evaluation.[20]
- Sport: WADA’s 2026 list bans GnRH (gonadorelin) and its agonist analogues in males under S2.2.1, at all times.[21]
This is general information, not legal advice.
