Synthetic copy of the brain's natural GnRH. Once FDA-approved for fertility and pituitary testing; both US human brands are discontinued.
Also called GnRH, LHRH, Gonadotropin-releasing hormone, Luteinizing hormone-releasing hormone, Gonadorelin acetate, Gonadorelin hydrochloride, Gonadorelin diacetate tetrahydrate, Factrel, Lutrepulse, Lutrelef, HRF, Cystorelin, Fertagyl, OvaCyst, GONAbreed
When Gonadorelin's status or evidence changes, it's in the next morning's email.
Gonadorelin is a lab-made copy of gonadotropin-releasing hormone (GnRH), the 10-amino-acid hormone the hypothalamus releases in pulses to tell the pituitary to make LH and FSH. LH and FSH in turn drive testosterone, estrogen, sperm and egg production. Gonadorelin is identical to the natural hormone, which is why it lasts only minutes in the blood: its initial half-life is about 2 to 10 minutes.
How it is given decides what it does. Pulses every 60 to 120 minutes switch the reproductive axis on; a constant supply switches it off, which is the principle behind long-acting GnRH drugs such as leuprolide. In the US it was approved as Factrel in 1982, a single 100 mcg injection used to test whether the pituitary can release LH, and as Lutrepulse in 1989, a pump that gives a small dose every 90 minutes to make women with hypothalamic amenorrhea ovulate. In trials of 268 women, 94% with primary hypothalamic amenorrhea ovulated. Both US human products are now discontinued. Outside the US, Lutrepulse has a Canadian monograph (revised 2016), France supplies it as Lutrelef under a shortage notice, and a UK product licence for a 100 mcg diagnostic injection was last updated in 2022.
Gonadorelin remains an FDA-approved veterinary drug: Factrel, Cystorelin, Fertagyl, OvaCyst and GONAbreed are used in cattle for ovarian cysts and to time insemination. In 2026 some men's health clinics prescribe compounded gonadorelin alongside testosterone, hoping to keep the testes working as hCG would. No published trial has tested that use. Pharmacies compound it on the basis that it is a component of FDA-approved drugs, while FDA warned a research-chemical seller in June 2026 that its gonadorelin was an unapproved new drug. WADA bans it in men at all times.
What it binds to, and what happens inside the body after that, step by step.
Gonadorelin binds the GnRH receptor on pituitary gonadotrope cells and triggers release of LH and FSH. The pituitary responds only to pulses: in monkeys with no hypothalamic signal, hourly pulses restored LH and FSH release while a continuous infusion did not and could shut it down again. That is why fertility pumps deliver a pulse every 90 minutes, and why a single injection is used as a diagnostic test.
Human results and animal results are kept apart below. A result in rats tells you a mechanism is plausible. It does not tell you what happens in a person.
Gonadorelin is an approved drug with decades of human use. Pulsatile gonadorelin reliably induces ovulation in women with hypothalamic amenorrhea, mostly from open studies, and induces puberty and sperm production in men with congenital hypogonadotropic hypogonadism. There is no published study of gonadorelin injections given with testosterone therapy, which is how it is mostly sold in 2026.
268 women aged 17 to 45 in four open, non-randomized studies
94% (45/48) of women with primary and 96% (94/98) with secondary hypothalamic amenorrhea ovulated; 12% of pregnancies with delivery data were multiples.
Read the study66 women, 212 treatment cycles, one Swiss center 1996 to 2020
Ovulation in 96% of cycles, live birth rate 65.9% per treatment, one twin pregnancy.
Read the study7 comparative studies, 420 men
Pulsatile GnRH brought sperm about 5.3 months sooner and larger testes than hCG/hMG, with no difference in sperm counts or pregnancy rates.
Read the study202 Chinese men (20 on pulsatile GnRH, 182 on hCG/hMG)
Median time to first sperm was 6 months with GnRH vs 18 months with hCG/hMG, though testosterone was lower on GnRH (8.3 vs 16.2 nmol/L).
Read the study45 men treated 2013 to 2023
Sperm appeared in 33 of 45 (73.3%); gynecomastia in 8, skin lumps at the pump site in 6 and allergic reactions in 3.
Read the study3 normal and 6 hypogonadal men, 100 mcg IV
Activity fell in two phases with half-lives of 2 and 10 minutes.
Read the studyRhesus monkeys with hypothalamic lesions
Hourly pulses restored LH and FSH release; a constant infusion did not, and switching to continuous dosing shut release down.
Read the studyWhen a new Gonadorelin study in people is published, the daily email covers it.
These are questions the published research has not answered.
Both US human products are listed as discontinued in Drugs@FDA. Gonadorelin remains FDA-approved for animals: Factrel (NADA 139-237) and Cystorelin (NADA 098-379) are labeled for ovarian follicular cysts and fixed-time insemination in cattle, with no milk or meat withdrawal time. In France, Lutrelef has been in short supply since December 2024, with new treatment starts stopped and normal supply expected in September 2028. WADA S2.2.1 names 'gonadotrophin-releasing hormone (GnRH, gonadorelin)' as a testosterone-stimulating peptide prohibited in males at all times.
When the FDA or WADA changes Gonadorelin's status, it's in the next morning's email.
How much of Gonadorelin is left after a single dose
Simple first-order model from the published half-life. Real clearance varies with dose, route, kidney and liver function and formulation. This is not a dosing schedule.
This table records the doses that trials and approved labels used, with the source for each row. It is a record of research, not a recommendation, and it is open to free members.
Which symptoms are expected and which mean stop and get help: side effects and red flags.
Tap a claim to see what the studies found.
Proven uses involve a pump delivering a pulse every 60 to 120 minutes. No published study has tested daily or twice-daily injections alongside testosterone.
The approved human brands, Factrel and Lutrepulse, are discontinued. Compounded gonadorelin is made under pharmacy rules and is not itself FDA-approved or reviewed.
Constant exposure to GnRH shuts LH and FSH release down. That is how long-acting GnRH agonists suppress testosterone in prostate cancer.
In 268 women in the Lutrepulse studies, 94% with primary hypothalamic amenorrhea ovulated, and a Swiss cohort reported a 65.9% live birth rate per treatment.
These pairings come up often. Almost none have been tested together in a trial, and the evidence note on each says so plainly.
Some men's health clinics add compounded gonadorelin to testosterone, as a substitute for hCG, to try to keep the testes producing testosterone and sperm.
EvidenceNo published study has tested this combination. Evidence for gonadorelin in men comes from pulsatile pumps in congenital hypogonadotropic hypogonadism, not from daily injections on top of testosterone.
The Lutrepulse label states the powder and its saline diluent are stable at room temperature, 15 to 30 C, in the unopened package.
Lutrepulse is reconstituted immediately before use and one pump reservoir lasts 72 hours. The label says to discard unused reconstituted solution.
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