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Peptide hormone (past FDA approvals, now discontinued)Limited humanNot FDA approved

Gonadorelin

Gonadorelin (synthetic gonadotropin releasing hormone)

Last reviewed October 27, 2026 · 16 sources · Written for general readers · Compare with another compound →

The bottom line

Gonadorelin is a lab made copy of GnRH, the brain hormone that tells the pituitary to release the hormones that run the testes and ovaries.[1] Both of its past US approvals for people are listed as discontinued, and in June 2026 FDA told a seller that no approved application is in effect for it.[2][3][4] It works in rare hormone conditions when given in pulses by a pump, but we found no published controlled trial in men taking testosterone, the use sellers promote most.[5][4]

Where the evidence stands

What it is

Gonadorelin is a synthetic version of gonadotropin releasing hormone (GnRH), a chain of 10 amino acids made in the hypothalamus, a small area at the base of the brain. Its sequence is the same as the body's own hormone.[1][6]

FDA approved Factrel, a gonadorelin hydrochloride injection, in 1982. It approved Lutrepulse, a gonadorelin acetate kit, in 1989 as an orphan drug (a drug for a rare condition). Both are now listed as discontinued.[2][3]

A product named Factrel is still sold as a veterinary drug for cattle, and its label says it is not for human use.[1]

Online sellers promote gonadorelin to support testosterone production and testicle function, especially in men on testosterone therapy.[4]

Name
Gonadorelin (Gonadorelin (synthetic gonadotropin releasing hormone))
Other names
GnRH, LHRH, luteinizing hormone releasing hormone, Factrel, Lutrepulse
Type
Peptide hormone (past FDA approvals, now discontinued)
Sequence
pGlu-His-Trp-Ser-Tyr-Gly-Leu-Arg-Pro-Gly-NH2
CAS number
33515-09-2
Formula
C55H75N17O13
Molecular weight
About 1182 g/mol

How it works

GnRH sits at the top of the chain that controls sex hormones.[1]

  • It triggers the pituitary gland to release LH and FSH, the two hormones that signal the testes and ovaries.[1]
  • Timing matters. In monkeys, GnRH given in hourly pulses restored these hormones, but a steady nonstop supply did not and could shut the response down.[7]
  • That is why medical use in people relied on small pumps that deliver pulses through the day.[5][8]
  • Testosterone taken from outside the body lowers the brain's own GnRH pulses, which lowers LH and FSH and can harm sperm production.[9] The idea behind gonadorelin in men on testosterone is to stand in for that missing signal.

The basic biology is well established. Whether occasional gonadorelin shots keep the testes working in men on testosterone has not been shown in published trials.

What the research shows

We keep animal and human evidence apart. A result in animals is a reason to study something in people, not proof that it works in people.

Animal and lab studies

Animal work explains why pulse timing matters

  • In rhesus monkeys with damage to the hypothalamus, hourly GnRH pulses restored pituitary hormone release while a constant infusion did not.[7]
  • Switching those monkeys from pulses to constant GnRH made the pituitary less responsive, a kind of shutdown.[7]
  • In cattle, gonadorelin is an approved veterinary drug used to treat ovarian cysts and to time breeding.[1]

Limit: Animal results explain the biology but say nothing about how gonadorelin works in men on testosterone.

Human studies

Small studies in rare hormone conditions, none in men on testosterone

  • In a 1982 study, 6 men who never went through puberty because of a GnRH problem received gonadorelin pulses from a portable pump. Within a month their testosterone rose from very low to normal adult levels, and all had erections, wet dreams and breast tenderness. Four had testicle growth, and three made sperm by about week 43.[5]
  • A placebo controlled trial of 39 women with no periods caused by low pituitary signals tested pulsed gonadorelin by pump. Half of the women in the main treatment groups ovulated versus none on placebo, and 7 of 19 became pregnant versus none on placebo.[8]
  • In that trial, no serious side effects occurred. The most common were breast tenderness, hot flushes, headache and mood swings, each in a few women.[8]
  • In a look back study of 202 men born without working GnRH signals, 20 used pulsed GnRH by pump and 182 used hormone shots for at least a year. Sperm appeared after a median of 6 versus 18 months, sperm movement was similar, and testosterone was lower on GnRH.[10]
  • In 155 men with the same condition, sperm production succeeded in 82% on pulsed GnRH versus 76% on hormone shots, not a real difference, though testicles ended larger, 15 versus 12 milliliters in volume.[11]
  • In 119 men with pituitary stalk interruption syndrome, a birth defect of the stalk linking brain and pituitary, sperm production succeeded less often on pulsed GnRH, 34% versus 52%, though faster in those who responded.[12]
  • In 28 men who had not responded to hormone shots, switching to pulsed GnRH led to sperm in 17 (61%) after a median of about a year.[13]
  • We found no published controlled trial testing gonadorelin in men taking testosterone, the use sellers promote most.[4]

Limit: Human studies are small or look back at records, studied rare conditions, and used all day pump pulses, which is very different from occasional shots.

Claims check

The most common claims about this compound, and what studies actually found. Verdicts rate the evidence, not whether you should use it.

Keeps testicles from shrinking on testosterone

Not tested

Testosterone therapy lowers LH and FSH, which can shrink the testes and cut sperm production.[9] Sellers promote gonadorelin to prevent this,[4] but we found no published controlled trial testing it in men on testosterone.

Protects fertility while on testosterone

Not tested

We found no published trial measuring sperm counts in men who used gonadorelin alongside testosterone. Fertility studies used all day pump pulses in men whose own GnRH was missing, a very different setting.[10][5]

Restarts hormones after a steroid cycle

Not tested

Testosterone from outside the body shuts down the brain's own GnRH signal,[9] and gonadorelin is pitched as a way to fill that gap. But no published study we found tested gonadorelin for hormone recovery after anabolic steroid use.

Raises natural testosterone

Mixed results

In 6 men who never went through puberty because of a GnRH problem, pulsed gonadorelin by pump raised testosterone from very low to normal adult levels within a month.[5] But in a 202 man comparison, testosterone was lower with pulsed GnRH than with hCG shots, 8.3 versus 16.2 nmol/L.[10] No study shows a rise in men with normal brain signals.

Restores sperm production in men with missing GnRH

Mixed results

In a 202 man study looking back at records, sperm first appeared after a median of 6 months with pulsed GnRH versus 18 months with hormone shots.[10] Another study of 155 men found similar success rates, 82% versus 76%, with a small speed advantage.[11] A third, in men with a pituitary stalk defect, found lower success with GnRH, 34% versus 52%.[12] None were randomized.

Helps women ovulate

Shown in people

In a placebo controlled trial of 39 women with no periods because of low pituitary signals, about half in the main pump groups ovulated versus none on placebo, and 7 of 19 became pregnant versus none on placebo.[8] The trial was small and used an all day pump, not occasional shots.

Known risks and side effects

  • Unproven for men on testosterone. No published trial shows that gonadorelin protects the testicles or fertility in men taking testosterone. The human studies used pulsed pumps in rare conditions.[5][8]
  • Wrong timing may backfire. Steady exposure to GnRH can make the pituitary less responsive instead of stimulating it, as seen in monkeys.[7]
  • Sterility problems. In 2022, a compounding pharmacy recalled compounded gonadorelin acetate and other drugs over sterility concerns, after reports of injection site abscesses, fever and rash linked to its recalled products.[14]
  • Unregulated online products. In June 2026, FDA warned a seller that its gonadorelin was an unapproved new drug and that research use only labels did not change that.[4]
  • Banned in sport. WADA bans GnRH, including gonadorelin, in male athletes at all times.[15]

Regulatory status

Today: No gonadorelin drug for people is marketed in the United States. Both past approvals are listed as discontinued, and in June 2026 FDA wrote that no approved application is in effect for gonadorelin.[2][3][4] It does not appear on FDA's compounding category lists, and WADA prohibits it in male athletes.[16][15]

  1. FDA approved Factrel, a gonadorelin hydrochloride injection. It is now listed as discontinued.[2]
  2. FDA approved Lutrepulse, a gonadorelin acetate kit, with orphan drug status. It is now listed as discontinued.[3]
  3. Ferring completed a placebo controlled phase 3 trial of pulsed gonadorelin in women with absent periods from low pituitary signals.[8]
  4. FDA alerted the public to a recall of compounded drugs, including gonadorelin acetate, from a Florida pharmacy over sterility concerns.[14]
  5. FDA sent a warning letter to an online seller, calling its gonadorelin an unapproved new drug.[4]

Sources

  1. Zoetis Inc. Factrel (gonadorelin injection) for cattle, NADA 139-237, label revised August 2022. FDA structured product label. FDA label
  2. US Food and Drug Administration. Drugs@FDA: FACTREL (gonadorelin hydrochloride), NDA 018123. Drugs@FDA
  3. US Food and Drug Administration. Drugs@FDA: LUTREPULSE KIT (gonadorelin acetate), NDA 019687. Drugs@FDA
  4. US Food and Drug Administration. Warning Letter to Wholesale Peptide, reference 729447. June 17, 2026. FDA warning letter
  5. Hoffman AR, Crowley WF Jr. Induction of puberty in men by long-term pulsatile administration of low-dose gonadotropin-releasing hormone. N Engl J Med. 1982;307(20):1237-1241. PMID 6813732
  6. FDA Global Substance Registration System. Gonadorelin, UNII 9O7312W37G. FDA GSRS
  7. Belchetz PE, Plant TM, Nakai Y, Keogh EJ, Knobil E. Hypophysial responses to continuous and intermittent delivery of hypopthalamic gonadotropin-releasing hormone. Science. 1978;202(4368):631-633. PMID 100883
  8. Ferring Pharmaceuticals. LutrePulse in Hypogonadotropic Hypogonadism (phase 3, randomized, placebo controlled). ClinicalTrials.gov NCT01976728, results posted. NCT01976728
  9. Hochu G, Geyer-Kim I, Kim E. Preserving spermatogenesis in testosterone deficiency: innovations in replacement and stimulatory therapies. Transl Androl Urol. 2025;14(12):3975-3987. DOI 10.21037/tau-2025-480
  10. Mao JF, Liu ZX, Nie M, Wang X, Xu HL, Huang BK, et al. Pulsatile gonadotropin-releasing hormone therapy is associated with earlier spermatogenesis compared to combined gonadotropin therapy in patients with congenital hypogonadotropic hypogonadism. Asian J Androl. 2017;19(6):680-685. PMID 28051040
  11. Zheng Y, Bai HZ, Zhao GC, Tian K, Yue JT, Li DM, et al. Comparison of outcomes between pulsatile gonadotropin releasing hormone and combined gonadotropin therapy in patients with congenital hypogonadotropic hypogonadism. Reprod Biol Endocrinol. 2025;23(1):46. PMID 40119359
  12. Zhang J, Zhu Y, Zhang R, Liu H, Sun B, Zhang W, et al. Pulsatile Gonadotropin-Releasing Hormone Therapy Is Associated With Better Spermatogenesis in Male Patients With Pituitary Stalk Interruption Syndrome. Endocr Pract. 2024;30(2):146-154. PMID 38029930
  13. Huang Z, Wang X, Yu B, Ma W, Zhang P, Wu X, et al. Pulsatile gonadotropin releasing hormone therapy for spermatogenesis in congenital hypogonadotropic hypogonadism patients who had poor response to combined gonadotropin therapy. Arch Endocrinol Metab. 2024;68:e230101. PMID 38739523
  14. US Food and Drug Administration. FDA alerts customers to voluntary recall of compounded drugs due to sterility issues by Drug Depot, LLC, dba APS Pharmacy. April 26, 2022. FDA
  15. World Anti-Doping Agency. The 2026 Prohibited List. WADA
  16. US Food and Drug Administration. Bulk Drug Substances Nominated for Use in Compounding Under Section 503A of the FD&C Act (category lists). Updated May 14, 2026. FDA category list
Medical disclaimer

This page is educational information only. It is not medical advice and does not replace care from a licensed medical provider. Do not use this page to decide whether to take any substance. Talk to a licensed medical provider first.

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