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Some human trialsFDA approved as Factrel +1

Gonadorelin

Also known as: GnRH · LHRH · Gonadotropin-releasing hormone · Gonadorelin acetate · Gonadorelin hydrochloride · Factrel · Lutrepulse

Updated 21 sources

Gonadorelin is synthetic GnRH, the brain signal that makes the pituitary release LH and FSH. FDA approved it as Factrel, a 100 mcg diagnostic test, and as Lutrepulse, a fertility pump; both are now discontinued. TRT users take compounded gonadorelin, usually 100 to 200 mcg two or three times a week, to keep the testes working in place of hCG. That use has no trial behind it, and its half-life is minutes.
Calculate with GonadorelinDosage chart

Quick facts

Half-life
  • Distribution half-life 2 to 10 minutes; terminal half-life 10 to 40 minutes
  • About 2 to 10 minutes, per one guide
Routes
  • Subcutaneous injection
  • Intravenous (IV)
Forms
  • Vial (powder)
  • Other form
Reported dose ranges
  • 5 to 200 mcg (subcutaneous injection)
  • 5 mcg (intravenous (iv))
Vial sizes
  • 2 mg, 5 mg, 10 mg
Chemistry
  • 1,182.33 g/mol · C55H75N17O13
FDA status
  • FDA approved as Factrel +1
Brand names
  • Factrel (Hikma): Pituitary function test, 100 mcg SC or IV. Approved 1982; all strengths discontinued.
  • Lutrepulse (Ferring): Pulsatile pump kit with 0.8 and 3.2 mg vials. Approved 1989 as an orphan drug; discontinued.
WADA
  • Prohibited

What people use Gonadorelin for

  • Keeping testicular size and function on TRT, as a substitute for hCG
  • Restarting natural testosterone after a steroid cycle or TRT (PCT)
  • Fertility in men and women with hypothalamic or hypogonadotropic hypogonadism, by pulsatile pump
  • Testing pituitary function, the original Factrel use
  • Veterinary breeding: an FDA-approved cattle product treats ovarian cysts

How it is thought to work. Gonadorelin has the same 10-amino-acid sequence as natural GnRH. It binds GnRH receptors on the pituitary and releases LH and FSH, which drive testosterone and sperm in men and ovulation in women. The body expects GnRH in pulses about every 1.5 to 2 hours. Pulses stimulate the axis; constant exposure shuts it down, which is how long-acting GnRH agonists like leuprolide suppress hormones.

Gonadorelin dosing

11 protocols from studies, guides and community reports, grouped by goal. Tap a source badge to see where a number came from.

Ovulation in hypothalamic amenorrhea2

Ovulation in hypothalamic amenorrhea, subQ pump (trial)

Amount
15 mcg
How often
One pulse every 90 minutes by pump
Route
SubQ, other form
Timing and details

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Ovulation in hypothalamic amenorrhea, IV pump (trial)

Amount
5 mcg
How often
One pulse every 90 minutes by pump
Route
IV, other form
Timing and details

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TRT add-on2

TRT add-on (guides)

Amount
100 to 200 mcg
How often
2 to 3 times a week
Route
SubQ, vial (powder)
Cycle
Ongoing while on TRT
Timing and details

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TRT add-on, community use

Amount
100 to 200 mcg
How often
2 to 3 times a week
Route
SubQ, vial (powder)
Cycle
Ongoing alongside TRT
Timing and details

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Other protocols: injected5

Pituitary function test, Factrel label

Amount
100 mcg
How often
One bolus
Route
SubQ, vial (powder)
Timing and details

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Step-up course from a 2 mg vial (guide)

Amount
50 to 150 mcg
How often
2 to 3 times a week on non-consecutive days
Route
SubQ, vial (powder)
Cycle
4 to 8 weeks
Titration (2 steps) and details

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Short daily course (guide)

Amount
100 to 200 mcg
How often
Daily or every other day, no more than 14 days in a row
Route
SubQ, vial (powder)
Cycle
14 days, then optionally 100 mcg 2 to 3 times a week
Titration (2 steps) and details

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Low-dose TRT add-on, community use

Amount
50 to 100 mcg
How often
2 to 3 times a week
Route
SubQ, vial (powder)
Cycle
Ongoing
Timing and details

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Restart after a cycle (PCT), community use

Amount
100 to 200 mcg
How often
Daily for the first 3 days, then 2 to 3 times a week
Route
SubQ, vial (powder)
Cycle
2 to 4 weeks
Timing and details

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Other protocols: injected (other form)2

Fertility in men with CHH, pump (trial)

Amount
10 mcg
How often
One pulse every 90 minutes, around the clock, by pump
Route
SubQ, other form
Cycle
Up to 24 months of follow-up
Timing and details

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Pump dose range (reference works)

Amount
5 to 20 mcg
How often
One pulse every 90 to 120 minutes by pump
Route
SubQ, other form
Timing and details

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Doses shown are what sources report, labelled by origin. Not medical advice.

Full Gonadorelin dosage guideEvery titration step in syringe units, missed doses and how to mix.

Vial strengths and syringe units

Every Gonadorelin vial size with the water volumes sources use. Units are what to draw on a U-100 insulin syringe, worked out exactly.
Gonadorelin: concentration and U-100 syringe units for each vial size and water volume
WaterStrength50 mcgdose, units100 mcgdose, units200 mcgdose, units
2 mg vial
2 mLCompetitor guide1 mg/mL50.05 mL100.1 mL200.2 mL
5 mg vial
1 mLCompetitor guide†5 mg/mL10.01 mL20.02 mL40.04 mL
2 mLCompetitor guide†2.5 mg/mL20.02 mL40.04 mL80.08 mL
10 mg vial
1 mLCompetitor guide10 mg/mL0.50.005 mLunder 1 unit10.01 mL20.02 mL
2 mLCompetitor guide5 mg/mL10.01 mL20.02 mL40.04 mL
Units are on a U-100 insulin syringe (100 units = 1 mL). U-50 and U-30 barrels read the same units.† Water volume sourced for a different vial size. The math is exact either way.Water volumes from

Doses shown are what sources report, labelled by origin. Not medical advice.

Calculate with this peptideYour vial, your water, your dose: Gonadorelin in syringe units, with the math shown.

Gonadorelin side effects

What trials and labels report, kept apart from what users and guides report. Frequencies are worded as each source states them.

Reported in studies and labels6

From clinical trials and regulatory documents.

  • Headache or light-headedness

    Rare after a single 100 mcg dose, per the Factrel label.

  • Nausea or stomach discomfort

    Rare after a single 100 mcg dose, per the Factrel label.

  • Flushing

    Rare after a single dose, per the Factrel label.

  • Injection-site swelling, pain or itch

    May occur after subcutaneous use, per the Factrel label; no rate given.

    How people manage it

    • Rotate injection sites.

  • Skin rash with long-term subQ use

    Local and generalized rashes noted after chronic subcutaneous use, per the label.

  • Allergic reactions, including anaphylaxis

    Rare, reported after repeated doses, per the Factrel label.

    How people manage it

    • Stop and get care for hives, wheezing, racing heart or facial swelling.

Reported by users and guides2

From community reports and dosing guides. Not measured rates.

  • Injection-site irritation, nausea, headache (user logs)

    One site's logs: nausea 2, injection-site irritation 2, headache 1, out of 25 reports.

  • Testicular shrinkage despite use

    Some TRT users report their testes still shrank on gonadorelin; others report it held. No numbers.

All 10 Gonadorelin side effects and how people manage themEvery management tip, who should not use it, and side-effect questions.

Who should avoid it

  • Allergy to gonadorelinCondition

    The only contraindication on the Factrel label.

  • Gonadotropin-secreting pituitary tumorCondition

    The label cites a report of pituitary apoplexy and sudden blindness after GnRH in a patient with this kind of adenoma.

  • Drug-tested sportCondition

    WADA's 2026 Prohibited List bans GnRH (gonadorelin) and its agonist analogues in male athletes (S2.2.1).

Storage

Powder (before mixing)

Temperature
25 °C

Factrel vials: room temperature, about 25 C.

Powder (before mixing)

Temperature
-20 to 8 °C

Research vials: guides say fridge (2 to 8 C) or freezer (-20 C), protected from light.

Mixed vial

Temperature
2 to 8 °C
Use within
14 to 28 days

Mixed research vials: 2 to 8 C, do not freeze. Guides give 14 days or 28 days.

Mixed vial

Use within
1 days

Factrel label: mix right before use, keep at room temperature, use within 1 day.

Mixed with: Bacteriostatic water (Factrel came with 2% benzyl alcohol in sterile water)

Mixing. A 2 mg vial in 2 mL gives 1 mg per mL, so 100 mcg is 10 units on a U-100 syringe. One calculator site mislabels its 10 mg in 1 mL default as 5 mg per mL; check the math for your own vial.

Stacks people report

Combinations from guides and community posts, with the reason given.
  • Hcg

    Some TRT users pair gonadorelin with low-dose hCG for fertility, per community summaries. hCG acts on the testes directly; gonadorelin needs a working pituitary.

  • Kisspeptin

    Kisspeptin releases the body's own GnRH and gonadorelin is GnRH, so users stack them for two-level axis stimulation. Untested as a pair.

  • Retatrutide

    Overlap, not synergy: retatrutide is the compound most often logged alongside gonadorelin on one site, with tesamorelin second.

Compare Gonadorelin

Evidence and legal status

Evidence: some human trials

Strong history for what it was approved for: a one-dose pituitary test, and pulsatile pumps that restore fertility in hypogonadotropic hypogonadism (for example 54 men in a 2025 study, 28 in 2019 and 2024 studies). For the popular use, 100 to 200 mcg shots a few times a week on TRT, we found no controlled human study.

FDA and WADA

FDA approved as Factrel +1

Approved by the FDA, but for a narrower use than people take it for here.

FDA approved gonadorelin as Factrel (1982, a pituitary function test) and Lutrepulse (1989, a fertility pump). Drugs@FDA lists both as discontinued, a marketing status, and shows no withdrawal of either approval. TRT use was never approved. It is not on the 503A category lists; the 503B nominations list has gonadorelin acetate in Category 1. A veterinary Factrel is approved for cattle.

Human gonadorelin now reaches US patients through compounding pharmacies, and research vials are sold separately. FDA marks gonadorelin acetate on its 503B list as a component of an FDA-approved drug. WADA's 2026 list names GnRH (gonadorelin) and its agonist analogues under S2.2.1, testosterone-stimulating peptides in males.

WADA: Prohibited

Gonadorelin questions

What is gonadorelin?

Synthetic GnRH, identical to the hormone the hypothalamus releases to make the pituitary put out LH and FSH. It was sold as Factrel and Lutrepulse; today it mostly reaches people through compounding pharmacies and research vials.

What is the gonadorelin dose on TRT?

Guides and community summaries cluster at 100 to 200 mcg under the skin, 2 to 3 times a week, for as long as TRT runs. Some clinics use 50 to 100 mcg. No trial has tested any of these doses in men on TRT.

What was the approved dose?

For the Factrel pituitary test, 100 mcg once, under the skin or IV, with blood drawn over the next 2 hours. For fertility, pumps gave about 5 to 20 mcg every 90 to 120 minutes.

Is gonadorelin FDA approved?

Yes, for narrow uses that are off the market. Factrel (1982) and Lutrepulse (1989) were approved, and Drugs@FDA now lists both as discontinued without showing any withdrawal of the approvals. TRT use was never approved. A veterinary Factrel for cattle is still an approved animal drug, and compounding pharmacies still make gonadorelin.

Can gonadorelin replace hCG?

It is the most common reason TRT users take it. Results reported in communities are mixed: some keep testicular size, others do not. hCG acts on the testes directly; gonadorelin depends on a pituitary that TRT is suppressing.

What is the half-life of gonadorelin?

Minutes. Reference works give a distribution half-life of 2 to 10 minutes and a terminal half-life of 10 to 40 minutes. That is why the medical version runs on a pump every 90 to 120 minutes.

Does 2 or 3 shots a week even work?

Unknown. Gonadorelin clears from blood within minutes, and no study has measured testicular size or sperm on that schedule in men on TRT. The studied regimens are pumps that pulse all day.

Can you take gonadorelin every day?

Guides disagree. One says never more than 3 days in a row, to avoid desensitizing the pituitary; another runs a 14-day daily course. Pump studies did dose all day, but in small pulses.

How many units is 100 mcg of gonadorelin?

With a 2 mg vial and 2 mL of water (1 mg per mL), 100 mcg is 10 units. With a 10 mg vial and 2 mL (5 mg per mL), it is 2 units. Use the calculator for your vial.

Does gonadorelin help fertility?

By pump, yes, in men and women whose own GnRH is missing. In 28 men with CHH, sperm appeared in 90% on the pump arm. In 12 women with hypothalamic amenorrhea, all ovulated. Shots a few times a week have not been tested for fertility.

What are gonadorelin side effects?

The Factrel label calls side effects rare after a single dose: headache, light-headedness, nausea, flushing and injection-site swelling or itch. Rashes came with long-term subQ use, and rare allergic reactions with repeated doses.

How do you store gonadorelin?

Research powder in the fridge or freezer. Once mixed, 2 to 8 C, not frozen, used within 14 to 28 days per guides. The old Factrel label said mix right before use and use within 1 day.

Is gonadorelin banned in sport?

Yes. WADA's 2026 list names GnRH (gonadorelin) and its agonist analogues under S2.2.1, testosterone-stimulating peptides in males.

Gonadorelin acetate vs hydrochloride?

Two salts of the same peptide. Factrel used the hydrochloride; Lutrepulse used the acetate.

Ask about Gonadorelin

Answers come from this site's pages only, with a link to each source.

Sources

21 sources, each checked by date. Record updated Oct 24, 2026. Numbers are restated in our own words and labelled by where they came from.

Reference work1

  1. GonadorelinWikipedia · checked Oct 24, 2026

Vendor guide1

  1. Compounded gonadorelin in men's healthEmpower Pharmacy · checked Oct 24, 2026

Competitor guide5

  1. Gonadorelin 2 mg vial dosage protocolpeptidedosages.com · checked Oct 24, 2026
  2. Gonadorelin 10 mg dosing calculatorpeptideprotocolwiki.com · checked Oct 24, 2026
  3. Gonadorelin (GnRH)outliyr.com · checked Oct 24, 2026

Community-reported1

  1. Gonadorelin: community protocols and reportspeptideprotocolwiki.com, via a competitor guide · checked Oct 24, 2026