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Lexicon
PCT & hormone control

Gonadorelin

Synthetic GnRH that prompts the pituitary to release LH and FSH, used to support testicular function.

3 min read 8 sources

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Gonadorelin acetate vial with white powder and the black TPD label on a white podium, next to a large blue 3D molecule model in a bright lab
Compound approved · in the US since 1982, no longer marketed there

Summary

At a glance

Sources checked on 26 Oct 2026

Until the first sperm
6 months

median with a gonadorelin pump, 14 months with HCG/HMG injections, 28 men1

Sperm produced
90 %

9 of 10 men with the pump within 24 months, 83.3% with HCG/HMG1

Testosterone after 1 month
520 ng/dl

77 ng/dl before, 6 men, pump with pulses under the skin2

Ovulation, highest pulse dose
55.6 %

5 of 9 women, 0 of 10 on placebo, phase 3 trial5

Phase 3 in the registry
4 trials

with gonadorelin itself, two of them as phase 2/3, as of 26 Oct 20266

  • Gonadorelin is the synthetic form of GnRH, the hormone from the hypothalamus that makes the pituitary release LH and FSH.82
  • The pattern is decisive: doses once an hour restored the hormone axis in monkeys, while a continuous infusion shut it down.3
  • In men with congenital hormone deficiency a pump giving pulses under the skin got testosterone and sperm production going, at the median earlier than HCG/HMG injections.21
  • In the US gonadorelin was approved from 1982, the acetate form followed in 1989. Both products are no longer marketed there.7
  • There is no study on preserving testicular function in athletes. Everything here is the state of research, not a recommendation.6
Profile

Updated May 2026

Class
GnRH

gonadotropin-releasing hormone

Use
Subcutaneous

in mcg

Half-life
very short

minutes

WADA
Banned

category S2

Sizes
2 to 5 mg

2 sizes in the shop

Contents 16 sections
  1. At a glance
  2. What is Gonadorelin?
  3. How it works
  4. What you need
  5. Reconstitution
  6. Dosing
  7. Injection
  8. What the research shows
  9. Research status
  10. Side effects
  11. Practice
  12. Storage
  13. Related compounds
  14. FAQ
  15. Glossary
  16. Sources

What is Gonadorelin?

Gonadorelin is the synthetic form of GnRH, the hormone that fires the starting signal for the whole hormone axis in the brain. It prompts the pituitary to release LH and FSH, which in turn drive the testes to produce testosterone and sperm.

In the performance corner it is used to support testicular function during or after a cycle, similar to the goal of HCG but one step higher up the axis.

Comparison

Four points on the hormone axis

Where the lexicon entries act on the brain, pituitary and testes axis. Tap a card to open its entry.

Releases GnRH Kisspeptin-10 KISS1R GnRHR LHCGR FSHR 1 of 4 targets
GnRH itself, short-acting Gonadorelin KISS1R GnRHR LHCGR FSHR 1 of 4 targets
GnRH derivative, long-acting Triptorelin KISS1R GnRHR LHCGR FSHR 1 of 4 targets Acts like LH HCG KISS1R GnRHR LHCGR FSHR 1 of 4 targets Acts like FSH and LH HMG KISS1R GnRHR LHCGR FSHR 2 of 4 targets

Simplified: kisspeptin releases GnRH, gonadorelin is GnRH, HCG and HMG act like LH and FSH directly on the gonads. Triptorelin acts on the same receptor as gonadorelin but for a long time and therefore shuts the axis down. 83

How it works

Gonadorelin activates the GnRH receptor of the pituitary and triggers a pulse of LH and FSH. The pulse pattern is decisive: the body releases GnRH naturally in bursts. Pulsatile dosing stimulates the axis, while constant continuous dosing would down-regulate it.

Because of the very short half-life, each dose acts only briefly, which fits the pulsatile principle.

Where it acts

Where gonadorelin acts

Tap a point or a card. Colour = GnRH receptor, grey = observed in studies.

  1. Pituitary gland

    Pulses restore the release of LH and FSH, a continuous infusion shuts it down (monkeys)3

    GnRHR
  2. Testes

    Testosterone from 77 to 520 ng/dl in one month, larger testes in 4 of 6 men2

    Observed in trials

Targets in the ChEMBL database8

Compound CHEMBL1200511: one recorded mechanism, Agonist (ChEMBL).

GnRH receptor
Gene
GNRHR
UniProt
P30968
ChEMBL
CHEMBL1855
Action
Agonist (ChEMBL)
Blue 3D molecules stream down from a glass opening onto glowing glass-like cell structures
Symbolic image.

What you need

Supplies

2 things, numbered as in the picture

Tick off what you already have. Vial and BAC water are our real shop photos at the same size.

Gonadorelin acetate vial and bacteriostatic water at the same size with the black TPD label, next to two U-100 insulin syringes, two alcohol swabs and a sharps container with a blue lid

  1. Gonadorelin vial

    The gonadorelin vial (lyophilized powder).

    In the shop

  2. BAC water, syringes and swabs

    Bacteriostatic water, U-100 insulin syringes, alcohol swabs.

    In the shop Amazon (opens a new tab)

As an Amazon associate we earn from qualifying purchases. Links open Amazon - no extra cost for you.

Reconstitution

Use the peptide calculator. A 2mg vial with 1ml water gives 2000mcg per ml, 100mcg is then 5 units on the U-100 syringe. Just add the water to the vial and let it dissolve.

Step by step

Dissolving the powder

Four steps, the same for every vial size.

  1. 1Wipe the cap

    Clean the rubber stopper with an alcohol swab.

  2. 2Add BAC water

    Just add it, it does not matter if it hits the powder directly.

  3. 3Swirl or shake

    Until everything has dissolved, both are fine.

  4. 4Draw up

    With the U-100 insulin syringe.

Less water higher concentration fewer units on the syringe Example: 2 mg + 1 ml = 2 mg/ml

Dosing

Dosing

Dosing, titration and syringe

Loading the dosing information …

  • Getting started and stepping up, drawn as a staircase
  • Units on the U-100 syringe for every step
  • How long one vial lasts

Injection

The injection is subcutaneous, into the fat layer under the skin. Common spots are the abdomen (keep about two finger-widths clear of the navel), the front and the inner side of the thigh, or the back of the upper arm.

The short version:

Injection

Where and at what angle

Pick a spot or switch the angle. Subcutaneous means: into the fat layer, not the muscle.

Rotate the spot each time, never the same one twice in a row.

90°More fat under the skin

Rule of thumb: where there is more fat under the skin, insert straight at 90 degrees. In lean people with little fat, 45 degrees, so the needle stays in the fat layer. Simplified diagram.

  1. Clean the spot with an alcohol swab and let it dry

  2. Pinch up a small fold of skin

  3. Insert the needle: at 90 degrees where there is more fat under the skin, at 45 degrees in lean people with little fat

  4. Inject slowly, wait a moment, then withdraw

  5. Put the needle straight into the sharps container

Rotate the site each time so the tissue does not get irritated. Never the same spot twice in a row.

What the research shows

A study (Zhang, 2019) showed that pulsatile gonadorelin via pump in men with congenital hypogonadism triggered sperm production even earlier than classic gonadotropin therapy. That underlines how important the natural pulse pattern is for the effect.

Study results

What the trials measured

Interactive: switch tabs, tap points, show or hide arms. Arms are named relative to each other, no dosing advice.

Time until the first sperm1

Median in months, 28 men with congenital hypogonadotropic hypogonadism, without sperm at the start

First sperm within 24 months1 Pulse pump versus HCG/HMG injections
Gonadorelin pump 6%
HCG/HMG injections 14%

Not randomised, 10 men on the pump, 18 on injections. In the end 90% and 83.3% had sperm, this difference was not significant.

Ovulation and pregnancy with the pump5

Women with hypogonadotropic hypogonadism, pump under the skin, three pulse doses versus placebo, phase 3

Ovulation5 9 to 10 women per arm
Placebo 0.0%
Lowest pulse dose 11.1%
Middle pulse dose 44.4%
Highest pulse dose 55.6%
Clinical pregnancy5 Gestational sac with heartbeat on ultrasound
Placebo 0.0%
Lowest pulse dose 0.0%
Middle pulse dose 22.2%
Highest pulse dose 50.0%

Results from the trial registry, very small groups. The trial compared three pulse doses, named here from lowest to highest.

Testosterone after one month on the pump2

6 men with idiopathic hypogonadotropic hypogonadism, mean

Testosterone in blood2 Pulses under the skin via a portable pump
Before treatment 77 ng/dl
After 1 month of pump 520 ng/dl

LH and FSH reached the normal range after one week and were above it after 14 days. Sperm production started in 3 of the 6 men by week 43.

A row of test tubes, each holding a small glowing glass brain model
Symbolic image.

Research status

Where the research stands

Shown are trials with gonadorelin itself, mostly as pulsatile GnRH via a pump. The many trials with long-acting GnRH derivatives are left out. As of 26 Oct 2026. 6

  1. Preclinical Monkeys with a disabled hypothalamus, pulses versus continuous infusion
  2. Phase 1 no registered trial
  3. Phase 2 1 trial, 1 completed
  4. Phase 3 4 trials, 3 completed
  5. Approval in the US since 1982, no longer marketed there
227 participants in phase 3 Planned figures for running trials Approved in the US in 1982 as hydrochloride and in 1989 as acetate, both products have since been discontinued there (Drugs@FDA). ChEMBL lists gonadorelin with phase 4 and as an agonist at the GnRH receptor.7
Show all 6 trials on a timelineHide timeline 5 completed 1 running 1 with results
Phase 2
Phase 3
Without phase

Bar: start to primary endpoint (planned for running trials). Green = completed, blue = progress until 26 Oct 2026.

Side effects

  • Generally well tolerated, mainly local reactions at the injection site.
  • With wrong (constant rather than pulsatile) use, down-regulation of the axis, the opposite effect.
  • Rarely headache, nausea.

Tolerability

Adverse events in the phase 3 trial

Women with hypogonadism, pump under the skin, 8 to 11 participants per arm.

36 of 100 Placebo
50 of 100 Lowest pulse dose
38 of 100 Middle pulse dose
40 of 100 Highest pulse dose
Event PlaceboLowest pulse doseMiddle pulse doseHighest pulse dose
Non-serious events5 36%50%38%40%
Serious events5 0%0%0%0%

About as frequent on placebo as on gonadorelin, there were no serious events. In the study with men an allergic skin redness at the pump site was a common side effect.51

Practice

  1. The pulse pattern is decisive, several small doses rather than one constant continuous dose.

  2. Because of the very short action, HCG is more practical for many when it is only about preserving the testes.

  3. Banned in official competition (WADA S2).

Hourglass, a glass of water and a white notebook on a bright table by the window

Storage

Before mixing the powder is robust, normal room temperature (around 20 to 25 degrees) is fine, ideally kept in the dark. After mixing, keep in the fridge (2 to 8 degrees), do not freeze. It stays good there for at least 4 to 6 months with barely any loss of potency, in practice considerably longer. Swirl or shake to mix, both are fine.

Shelf life

How long it keeps

Undissolved (powder) Room temperature, around 20 to 25 degrees, dark

Robust, no fridge needed. Best kept in the dark.

Dissolved (mixed) Fridge, 2 to 8 degrees, do not freeze

At least 4 to 6 months with barely any loss of potency.

  • Keep it dark
  • Dissolved: 2 to 8 degrees
  • Note the mixing date on the vial
Nine vials with white powder and blue caps in the door shelf of a bright fridge
Powder dark at room temperature, once dissolved into the fridge (2 to 8 degrees), stable there for at least 4 to 6 months. Symbolic image.

Related

Related compounds

Same receptors or a different path: all in the TPD lexicon.

Gonadorelin
Triptorelin Same receptor, long-acting Kisspeptin-10 Different path: releases the body's own GnRH Kisspeptin-10 Nasal Spray Kisspeptin as a nasal spray HCG Different path: acts like LH directly on the testes HMG Different path: acts like FSH and LH Enclomiphene (Androxal) Different path: raises the body's own release via the brain Clomid (Clomiphene) Different path: raises the body's own release via the brain

FAQ

Common questions about Gonadorelin

Short answers, each backed by the sources below.

Is gonadorelin approved?

Yes, the compound is approved. In the US it came to market in 1982 as hydrochloride and in 1989 as acetate. According to Drugs@FDA both products have since been discontinued there. ChEMBL lists gonadorelin with phase 4.78

Why does the pulse pattern matter so much?

In monkeys without their own GnRH release, doses once an hour restored the hormone axis. A continuous infusion did not and even shut the pituitary down. The pattern mattered, not the amount. That is why human studies use pumps that deliver pulses.32

What do the studies in men show?

In 6 men with congenital hormone deficiency testosterone rose from 77 to 520 ng/dl after one month on the pump. By week 43, 3 of them were producing sperm. In a study of 28 men the first sperm appeared at a median of 6 months with the pump and 14 months with HCG/HMG injections.21

Is gonadorelin better than HCG?

In the study with 28 men sperm appeared earlier with the pump, but in the end a similar share of men had sperm. With HCG/HMG testosterone tended to be higher, with more acne and breast tenderness. For preserving testicular function during a steroid cycle there is no study for either approach.1

What does GnRH have to do with Down syndrome?

A 2022 paper found too little GnRH in the brain of mice with Down syndrome. Raising the level improved their sense of smell and memory. In adults with Down syndrome pulsatile GnRH improved cognition and brain connectivity. A placebo-controlled phase 2/3 trial is expected to run until 2028.46

Which side effects are known?

In the phase 3 pump trial 37.5 to 50 percent had a non-serious event on gonadorelin and 36.4 percent on placebo, with no serious events. In the study with men an allergic skin redness at the pump site was common. Continuous dosing instead of pulses shuts the axis down.513

Glossary

Terms explained briefly

Dotted words in the text open these explanations directly.

Downregulation
The cell responds more weakly when a signal is present all the time. With GnRH, LH and FSH then fall.
FSH (follicle-stimulating hormone)
Pituitary hormone. In men important for sperm production.
GnRH
Gonadotropin-releasing hormone from the hypothalamus. It controls the release of LH and FSH.
Hypogonadotropic hypogonadism
Underactive gonads because the signals from the brain and pituitary are missing.
LH (luteinising hormone)
Pituitary hormone. In men it stimulates testosterone production in the testes.
Lyophilisate
Freeze-dried powder. Without water a peptide keeps much longer.
Pituitary gland
Small gland below the brain that releases hormones in response to signals from the hypothalamus.
Pulsatile
In single bursts rather than evenly. This is how the body releases GnRH.
Sperm production
Formation of sperm in the testes, driven by FSH and testosterone.
Subcutaneous
Into the fat layer just under the skin.

Evidence

Sources

Show all 8 sourcesHide sources 4 Studies2 Trial registry2 Database checked 26 Oct 2026

Studies

  1. Gonadorelin pump versus HCG/HMG in congenital hormone deficiency

    Zhang et al., American Journal of Men's Health, 2019

    DOI 10.1177/1557988318818280 PMID 30569789
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed
  2. Puberty in men induced by GnRH pulses from a pump

    Hoffman & Crowley, New England Journal of Medicine, 1982

    DOI 10.1056/NEJM198211113072003 PMID 6813732
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed
  3. Pulsed versus continuous GnRH in monkeys

    Belchetz et al., Science, 1978

    DOI 10.1126/science.100883 PMID 100883
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed
  4. GnRH and cognition in Down syndrome

    Manfredi-Lozano et al., Science, 2022

    DOI 10.1126/science.abq4515 PMID 36048943
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed

Trial registry

  1. Results of the phase 3 pump trial in the registry

    ClinicalTrials.gov, NCT01976728 (Ergebnisse eingetragen)

    NCT01976728
    Checked 26 Oct 2026 via ClinicalTrials.gov API v2
  2. Trials with gonadorelin on ClinicalTrials.gov

    ClinicalTrials.gov, U.S. National Library of Medicine

    Checked 26 Oct 2026 via ClinicalTrials.gov API v2

Database

  1. US approvals of gonadorelin (both discontinued)

    Drugs@FDA, NDA 018123 (1982) und NDA 019687 (1989)

    Checked 26 Oct 2026 via openFDA
  2. Gonadorelin acetate in ChEMBL (phase 4, GnRH receptor agonist)

    ChEMBL, EMBL-EBI (CHEMBL1200511, CHEMBL1007)

    Checked 26 Oct 2026 via ChEMBL

In the shop

Gonadorelin in the catalog

Sizes, prices and shipping times are on the product page.

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