Gonadorelin (GnRH): medical use, research, side effects and status in Finland

In short

Gonadorelin is a synthetic form of the body's own GnRH hormone, used as a medicine for a pituitary function test [4]official and, given by a pump, to induce ovulation [7]B. It has no marketing authorisation in Finland, and the human evidence is mostly small studies [2]regulator [7]B.

• Gonadorelin makes the pituitary release the hormones LH and FSH, which drive the ovaries and testes [4]official. The effect depends on how it is given: in monkeys a continuous infusion did not restore hormone release, but pulses given once an hour did [6]C.
• The best human evidence concerns women whose periods have stopped because of the brain's control: in a meta-analysis of 35 studies, the ovulation rate with pump treatment was high [7]B.
• Weakness: in polycystic ovary syndrome (PCOS) the trials were too small to prove or rule out a benefit [8]A, and as a hormone test a single injection does not reliably tell a permanent hormone deficiency from delayed puberty [14]B.
• In Finland gonadorelin is on the medicines list, but it has no marketing authorisation [1, 2]regulator. WADA bans it in men at all times [21]regulator.

What is gonadorelin?

Gonadorelin is a synthetic form of gonadotropin-releasing hormone (GnRH). GnRH is a ten-amino-acid peptide made in the hypothalamus of the brain, which travels by a short blood-vessel route to the pituitary gland [20]D. There it makes the pituitary produce and release luteinising hormone (LH) and follicle-stimulating hormone (FSH) [4]official.

Gonadorelin is not approved across the whole EU. It was not in the EMA data set of centrally authorised medicines on 14 Oct 2026 [3]regulator. The EMA Article 57 data (as of 9 Oct 2026) listed nationally authorised gonadorelin products in six countries [2]regulator:

• Lutrelef and Lutrepulse (gonadorelin): products given under the skin or into a vein in France, Austria, the Netherlands and Germany [2]regulator.
• LHRH Ferring (gonadorelin): a product given into a vein in France and Germany [2]regulator.
• Kryptocur (gonadorelin): a nasal product in Germany, Austria and Italy [2]regulator.
• Gonadorelin (Esteve): a product given under the skin or into a vein in Northern Ireland [2]regulator. Its UK Summary of Product Characteristics is the main official source of this page, and it lists the product as a prescription-only medicine [4]official.

Gonadorelin has no marketing authorisation in Finland, but it is on Fimea's medicines list [1, 2]regulator. Basics: What are peptides?. All substances: Peptides A-Z.

Evidence at a glance

Each cell gives the kind of study and the source. The letter is the level of evidence, not the result.

"-" = no such study is known. For a substance used as a medicine, the evidence comes mainly from human studies.

What is gonadorelin used for?

Gonadorelin is used in two very different ways: as a single injection in a hormone test, and given in pulses by a pump in infertility treatment [4]official [7]B. Nasal gonadorelin has also been studied for undescended testis [16]B [18]A.

• Pituitary function test: the only indication in the UK Summary of Product Characteristics. After one injection, LH is measured in the blood several times over two hours. The test is used for suspected gonadotropin deficiency and to check pituitary function, for example after surgery or radiotherapy for a pituitary tumour [4]official.
• Inducing ovulation in women: when periods have stopped because of the hypothalamus, a pump delivers the hormone under the skin or into a vein in pulses [7]B [10]B.
• Sperm production in men: in congenital hypogonadotropic hypogonadism (a brain-related lack of sex hormones), pump treatment has been compared with gonadotropin injections [12]B.
• Undescended testis (research use): as a nasal spray before surgery or instead of it [16]B [18]A.

According to the Summary of Product Characteristics, a single test does not show why the response is weak and does not measure the pituitary's reserve [4]official.

How does gonadorelin work?

Gonadorelin binds to cells in the front lobe of the pituitary and makes them produce and release LH and FSH [4]official. LH and FSH in turn drive hormone production and the maturation of eggs and sperm in the ovaries and testes. In a normal menstrual cycle the body's own GnRH is released in pulses every 60-120 minutes [8]A.

The rhythm is what matters. GnRH given in pulses keeps the pituitary working, but given continuously it shuts it down [6]C. This is why treatment uses a pump that delivers the hormone in pulses [7]B.

Animal studies: pulses or continuous delivery

In a classic experiment, part of the hypothalamus had been destroyed in rhesus monkeys, so their pituitary no longer released gonadotropins. A continuous GnRH infusion did not restore the release, but GnRH given once an hour did. When monkeys whose release had recovered were switched to continuous delivery, the release stopped again [6]C.

According to the authors, the effect depended on the pattern of delivery, not on the amount of hormone [6]C.

Healthy men

In an experiment with six healthy young men, a five-day fast lowered blood testosterone and LH by 30-50%. When the men received pulsed GnRH into a vein during the fast, the fall in testosterone was prevented [19]B. The study did not measure any health benefit and did not test a single injection under the skin.

Has gonadorelin been studied in humans?

Yes, but mostly in small studies. Most of the evidence is observational studies and meta-analyses of them; randomised trials are few and small [7, 12]B [8]A.

Inducing ovulation in women

• Meta-analysis (2018). 35 studies (3 randomised, 32 observational) included 1,002 women whose periods had stopped because of the hypothalamus. Pump treatment achieved a high ovulation rate, and given under the skin the result was similar to that given into a vein [7]B.
• Case series (2017). Ovulation was documented in all 12 women, and in 30 of 33 treatment cycles only one follicle matured. Seven women became pregnant, ten times in all. In one woman with PCOS the same treatment did not lead to ovulation [10]B.
• Placebo-controlled trial (completed 2018). In a placebo-controlled trial funded by Ferring, 39 women with a congenital brain-related hormone deficiency received gonadorelin by pump at three different pulse strengths, or placebo. In the two strongest groups 9/18 ovulated, in the placebo group 0/10. The results have been published only in the registry, not peer-reviewed [11]E, not peer-reviewed.
• PCOS together with absent periods of hypothalamic origin (2013). In a randomised trial of 30 women, the pregnancy rate was 46% with pump treatment and 0% with gonadotropin treatment, although the ovarian response was similar in the groups [9]A.

Men

In a meta-analysis of seven studies and 420 men, sperm began to appear about five months earlier on pump treatment than on gonadotropin injections, and the testes grew more. There was no difference in finding sperm, in sperm concentration or in the pregnancy rate. The authors call for high-quality randomised trials [12]B.

Hormone test

In a French study of 232 males, the LH response to the GnRH test varied widely. In 47% of those with a permanent hormone deficiency the response fell in the same range as in delayed puberty, so the test did not separate the two reliably [14]B. In an Italian series of 136 girls, the standard GnRH test raised LH more than the triptorelin test, which has come into use because gonadorelin is poorly available [15]B.

Undescended testis

In a meta-analysis of 1,255 undescended testes, hormone given into the nose made the testis descend fully in 20.9%, placebo in 5.6%. Side effects were more common in the hormone group, but they were slight and temporary, and for testes that could not be felt there was no difference between the groups [16]B. In a Czech randomised trial of 36 infants, nasal gonadorelin before surgery did not change testis size or hormone levels compared with surgery without hormone [18]A.

Who studies gonadorelin?

Gonadorelin is studied by reproductive medicine and paediatric endocrinology units. Examples are Lausanne University Hospital (inducing ovulation) [10]B, Nantes University Hospital (PCOS) [9]A, two French centres (hormone test) [14]B and the General University Hospital in Prague (undescended testis) [18]A. The drug company Ferring funded the placebo-controlled trial of its pump product [11]E, not peer-reviewed. The doping research centre of the German Sport University Cologne has developed a method to find gonadorelin in urine [20]D.

Author of this page: editorial team

This page was written by the Molecular Recovery editorial team. The draft was made with the help of AI, and the claims were checked against the sources (AI policy). The page has not been medically reviewed. How we work: About us.

How long does gonadorelin stay in the body?

A very short time. According to the Summary of Product Characteristics, gonadorelin is broken down quickly in the blood and excreted in urine, and its half-life is about 4 minutes [4]official.

In treatment the hormone is given in repeated pulses by a pump [7]B. In a doping-control method study, intact GnRH was found in urine after it had been given, but not in ordinary samples [20]D.

What are the side effects of gonadorelin?

According to the Summary of Product Characteristics, side effects of a single injection are fairly uncommon, but hypersensitivity reactions have been reported [4]official. Long pump treatment has its own risks [7, 13]B.

Single injection (hormone test)

• Uncommon: pain, swelling and itching [4]official.
• Rare: fast heartbeat, nausea, abdominal discomfort, headache, dizziness, flushing, hives, narrowing of the airways, hardening at the injection site, hypersensitivity reactions and antibody formation [4]official.
• Frequency not known: sepsis, heavy periods, rash and inflammation of a vein [4]official.
• Warnings: given early in the menstrual cycle, gonadorelin can cause premature ovulation. In a pituitary tumour, bleeding into the pituitary can occur, so gonadorelin and its analogues are not recommended for these patients [4]official.

Pump treatment

According to the meta-analysis, ovarian hyperstimulation was rare and mild, multiple pregnancies were uncommon but slightly more common than in the general population, and treatment into a vein rarely caused superficial vein inflammation [7]B. In men, allergic reactions were more common on pump treatment, whereas breast growth and acne were more common on gonadotropin treatment [12]B.

In a series of five men, one developed antibodies against GnRH. The treatment worked at first, but then hormone levels and testosterone fell back to the starting level [13]B. More: Side effects and safety.

Nasal spray in children

In the treatment of undescended testis, side effects were more common in the hormone group than in the placebo group [16]B, but according to a review they were mild and transient [17]. In the infant trial the treatment was judged safe in the medium term; the long-term effects need further follow-up, according to the authors [18]A.

Interactions and who lacks data

According to the Summary of Product Characteristics, the test is done without medicines that directly affect the pituitary's release of gonadotropins, such as products containing androgens, oestrogens, progestogens or glucocorticoids. Spironolactone can raise gonadotropins temporarily, and oral contraceptives and digoxin can lower them. Phenothiazines and other dopamine blockers that raise prolactin can blunt the response [4]official.

Gonadorelin must not be given to pregnant or breastfeeding women. There are no data on safety or efficacy in children under one year [4]official.

What speaks against it and what is unknown

Gonadorelin works when the hypothalamus's own hormone release is missing and the treatment is given in pulses. In other situations the evidence is weak or negative [7]B [8]A [14]B [18]A.

Counter-evidence

• In PCOS, four small randomised trials (57 women) were too small and short to prove or rule out a benefit, according to the Cochrane review [8]A.
• In men, pump treatment did not improve the pregnancy rate or sperm concentration compared with gonadotropin treatment [12]B.
• The GnRH test did not reliably separate congenital hormone deficiency from delayed puberty [14]B.
• In undescended testis, the success rates of hormone treatment generally exceeded placebo by no more than 10 percentage points, and the studies were mostly of fair or poor quality [17]. In infants the treatment did not change testis size or hormone levels [18]A.

What the evidence does not support

• "Gonadorelin raises testosterone after anabolic steroid use": no such study has been published (as of October 2026). For healthy men there is only a fasting experiment in six men, in which the hormone was given into a vein by pump in pulses [19]B.
• "The more, the better": continuous exposure shuts down the pituitary. In monkeys continuous delivery did not restore hormone release [6]C.
• "Gonadorelin is approved in Finland": the EMA data showed no Finnish marketing authorisation on 9 Oct 2026 [2]regulator.

What is not known

• Whether pump treatment is better than gonadotropin injections in men: the authors call for high-quality randomised trials [12]B.
• The long-term effects in infants whose undescended testis was treated with hormone [18]A.
• How common antibodies are in long pump treatment: the information comes from a case series [13]B.
• The effect of repeated injections under the skin in healthy men: it has not been studied.

Gonadorelin dosing in studies

Gonadorelin is a prescription medicine at least in the UK [4]official, so this site has no dose page or calculator for it. It has no marketing authorisation in Finland [2]regulator.

The study designs in brief, without doses: in the hormone test one injection is given under the skin or into a vein, and blood samples are taken over two hours [4]official. In inducing ovulation, a pump gave the hormone in pulses every hour and a half until ovulation was documented, after 17 days on average [10]B. The placebo-controlled trial compared three pulse strengths [11]E, not peer-reviewed.

What the numbers cannot tell you. The treatment was given in a university hospital, where hormone levels and follicle growth were monitored [10]B. The designs are not treatment instructions, and nothing can be concluded from them about any other use. Research doses of other substances: Dosing.

Gonadorelin vs triptorelin: what is the difference?

Gonadorelin resembles the body's own GnRH, and its half-life is minutes [4]official. Triptorelin is a long-acting GnRH analogue [15]B. In a diagnostic test, the standard GnRH test raised LH more, and in the triptorelin test the LH peak came later and stayed lower [15]B.

In fertility treatment gonadorelin is most often compared with gonadotropin injections. In men, sperm appeared earlier on pump treatment, but the pregnancy rate did not differ [12]B. A related substance has its own page: Kisspeptin.

Combinations and blends

In studies gonadorelin has been combined with FSH and given after pre-treatment with a GnRH agonist, but each comparison rested on only one small trial [8]A. Gonadorelin is not in any blend on this site, and combining it with other peptides has not been studied.

Status in the United States

On 15 Oct 2026 the US DailyMed database held five gonadorelin labels, and all were prescription animal drug labels, for example Factrel (gonadorelin) and Cystorelin (gonadorelin) [5]regulator. It held no gonadorelin product intended for humans.

Is gonadorelin legal in Finland?

In Finland gonadorelin is a medicinal substance without an authorised product. It is named in annex 1 of Fimea's medicines list, and under the decision the substances in annex 1 are controlled as medicines [1]regulator.

• Marketing authorisation. The EMA Article 57 data showed no Finnish marketing authorisation on 9 Oct 2026. National authorisations existed in Germany, Austria, France, the Netherlands, Italy and Northern Ireland [2]regulator. There is no central EU authorisation [3]regulator.
• Doping offence law. Gonadorelin is not named among the Criminal Code doping substances listed in Government Decree 705/2002 [23]regulator.
• Import. Ordering medicines from abroad is covered on Peptides and the law in Finland. Bringing them back from travel: Travelling with peptides.

This is not legal advice. Disclaimer.

Is gonadorelin doping?

Yes, in men. On the WADA 2026 Prohibited List gonadorelin is in class S2.2.1, testosterone-stimulating peptides in males, and the substances in this class are prohibited at all times, also out of competition [21]regulator. The Finnish SUEK list names gonadorelin and GnRH under the same item [22]regulator.

According to doping-control researchers, intermittent GnRH can raise testosterone in young men, which is why the substance is subject to doping control. A urine method has been developed that found the intact hormone after it had been given [20]D.

How is the quality of a gonadorelin product judged?

There is no authorised gonadorelin product in Finland [2]regulator, so there is no gonadorelin product assessed by the authority here. A doping research method shows that GnRH can be identified by mass spectrometry [20]D, but it says nothing about the purity of any individual product.

A certificate of analysis (COA) does not show that a product is safe. More: How to read a COA and check a test result.

FAQ

Read the research yourself: sources

Every source opens the original publication or the regulator's page. The level shows what the source itself reports.

1. Finland. Lääkeluettelo (Fimea medicines list), 230/2025, annex 1: "Gonadoreliini". Finlex regulator
2. European Medicines Agency. Article 57 product data (EMA/518502/2018 Rev.90, data as of 9 Oct 2026): gonadorelin entries in Germany, Austria, France, the Netherlands, Italy and Northern Ireland; none in Finland. EMA regulator
3. European Medicines Agency. Medicine data (centrally authorised medicines, data set of 14 Oct 2026): no product with gonadorelin. EMA regulator
4. Esteve Pharmaceuticals Ltd. Gonadorelin 100 micrograms powder for solution for injection: Summary of Product Characteristics (UK, PL 17509/0005, prescription only medicine, text revised 30 Aug 2022). electronic medicines compendium (emc). emc official
5. U.S. National Library of Medicine, DailyMed. Search "gonadorelin" (15 Oct 2026): five labels (Factrel, Gonabreed, Cystorelin, Fertagyl, OvaCyst), all of the type "prescription animal drug label". DailyMed (NIH) regulator
6. 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 C
7. Tranoulis A, Laios A, Pampanos A, et al. Efficacy and safety of pulsatile gonadotropin-releasing hormone therapy among patients with idiopathic and functional hypothalamic amenorrhea: a systematic review of the literature and a meta-analysis. Fertil Steril. 2018;109(4):708-719.e8. PMID 29605411 B
8. Bayram N, van Wely M, van der Veen F. Pulsatile gonadotrophin releasing hormone for ovulation induction in subfertility associated with polycystic ovary syndrome. Cochrane Database Syst Rev. 2004;2003(1):CD000412. PMID 14973957 A
9. Dubourdieu S, Fréour T, Dessolle L, Barrière P. Prospective, randomized comparison between pulsatile GnRH therapy and combined gonadotropin (FSH+LH) treatment for ovulation induction in women with hypothalamic amenorrhea and underlying polycystic ovary syndrome. Eur J Obstet Gynecol Reprod Biol. 2013;168(1):45-48. PMID 23298894 A
10. Christou F, Pitteloud N, Gomez F. The induction of ovulation by pulsatile administration of GnRH: an appropriate method in hypothalamic amenorrhea. Gynecol Endocrinol. 2017;33(8):598-601. PMID 28277105 B
11. ClinicalTrials.gov. NCT01976728: LutrePulse Hypogonadotropic Hypogonadism (phase 3, sponsor Ferring Pharmaceuticals, double-blind, randomised, placebo-controlled, 39 participants, completed Feb 2018, results posted in the registry). Registry record, not peer-reviewed. ClinicalTrials.gov E, not peer-reviewed
12. Wei C, Long G, Zhang Y, et al. Spermatogenesis of Male Patients with Congenital Hypogonadotropic Hypogonadism Receiving Pulsatile Gonadotropin-Releasing Hormone Therapy Versus Gonadotropin Therapy: A Systematic Review and Meta-Analysis. World J Mens Health. 2021;39(4):654-665. PMID 32777865 B
13. Blumenfeld Z, Frisch L, Conn PM. Gonadotropin-releasing hormone (GnRH) antibodies formation in hypogonadotropic azoospermic men treated with pulsatile GnRH: diagnosis and possible alternative treatment. Fertil Steril. 1988;50(4):622-629. PMID 3139467 B
14. Mosbah H, Bouvattier C, Maione L, et al. GnRH stimulation testing and serum inhibin B in males: insufficient specificity for discriminating between congenital hypogonadotropic hypogonadism from constitutional delay of growth and puberty. Hum Reprod. 2020;35(10):2312-2322. PMID 32862222 B
15. Sodero G. The Diagnostic Utility of the Triptorelin Stimulation Test Compared to the Standard Gonadotropin-Releasing Hormone Stimulation Test in Children with Idiopathic Central Precocious Puberty. Diseases. 2025;13(11):370. PMID 41294910 B
16. Li T, Gao L, Chen P, et al. A systematic review and meta-analysis of comparative studies assessing the efficacy of luteinizing hormone-releasing hormone therapy for children with cryptorchidism. Int Urol Nephrol. 2016;48(5):635-644. PMID 26898822 B
17. Penson D, Krishnaswami S, Jules A, McPheeters ML. Effectiveness of hormonal and surgical therapies for cryptorchidism: a systematic review. Pediatrics. 2013;131(6):e1897-e1907. PMID 23690511 (review)
18. Fiala V, Jiraskova Z, Drlik M, et al. The safety of neoadjuvant hormonal treatment in infants with cryptorchidism. J Pediatr Urol. 2022;18(6):846.e1-846.e6. PMID 35691791 A
19. Aloi JA, Bergendahl M, Iranmanesh A, Veldhuis JD. Pulsatile intravenous gonadotropin-releasing hormone administration averts fasting-induced hypogonadotropism and hypoandrogenemia in healthy, normal weight men. J Clin Endocrinol Metab. 1997;82(5):1543-1548. PMID 9141547 B
20. Thomas A, Geyer H, Kamber M, Schänzer W, Thevis M. Mass spectrometric determination of gonadotrophin-releasing hormone (GnRH) in human urine for doping control purposes by means of LC-ESI-MS/MS. J Mass Spectrom. 2008;43(7):908-915. PMID 18563864 D
21. World Anti-Doping Agency. 2026 Prohibited List (in force 1 Jan 2026), class S2.2.1. WADA regulator
22. Finnish Center for Integrity in Sports (SUEK). Dopingaineryhmät ja -aineet 2026 (Finnish version of the WADA list), S2.2.1. SUEK regulator
23. Finland. Government Decree 705/2002 on the doping substances referred to in Chapter 44, section 16(1) of the Criminal Code. Finlex regulator

Research sources (PubMed) and regulatory and registry sources read on 15 Oct 2026.

Evidence levels: A = randomised human trial or meta-analysis · B = observational human study or case series · C = animal study · D = cell or laboratory study · E = not peer-reviewed · regulator = a regulator's assessment or decision, not research evidence. The marker official means official product information (summary of product characteristics or label); it is not research evidence. For a review, the level shows what kind of research the statement rests on. No level: statements that something has not been studied, reviews' interpretations, named hypotheses and the general rules in our certificate-of-analysis guide.

Content is general information about research, not medical advice. If you have symptoms, contact a healthcare professional.