Gonadorelin
| Category | Other Peptides |
| Goals | Sexual Health |
| Evidence level | Approved (established GnRH drug; long clinical history) |
| Legal status | Prescription drug |
| FDA status | Previously approved (Factrel/Lutrepulse); no branded product currently marketed in US |
| Half-life | ~2–4 minutes (very short) |
| Routes | Subcutaneous · Intravenous (pulsatile pump historically) |
| CAS / MW / Sequence | 33515-09-2 · 1182.3 g/mol · pGlu-His-Trp-Ser-Tyr-Gly-Leu-Arg-Pro-Gly-NH2 (decapeptide) |
| Last reviewed | 2026-06-05 |
In one line
Synthetic gonadotropin-releasing hormone (GnRH) — chemically identical to the body’s own GnRH — used to stimulate the pituitary to release LH and FSH, for diagnostic testing, fertility, and (off-label) HPG-axis support alongside TRT.
Evidence at a glance
Gonadorelin is GnRH and has a long, established clinical history (diagnostic GnRH stimulation tests; pulsatile fertility therapy). However, branded FDA-approved products (Factrel, Lutrepulse) are no longer marketed in the US, and much current use — especially alongside testosterone therapy — is via compounding pharmacies and is off-label. See Evidence Grading Explained and the Disclaimer.
Key Takeaways
- A decapeptide identical to natural GnRH (also called LHRH), made in the hypothalamus.
- Acts directly on the pituitary to release LH and FSH, which drive the gonads (testosterone, sperm, estrogen, ovulation).
- Pulsatile (intermittent) dosing stimulates the axis; continuous GnRH exposure paradoxically suppresses it (the basis of GnRH-agonist downregulation).
- Long history of approved use for diagnostic GnRH-stimulation testing and pulsatile fertility therapy; no branded product is currently marketed in the US.
- Popular off-label alongside TRT to maintain testicular function/size and fertility — replacing the historical role of hCG.
What Is It
Gonadorelin is synthetic GnRH (gonadotropin-releasing hormone, a.k.a. LHRH), a 10-amino-acid peptide structurally identical to the hormone the hypothalamus secretes to control reproduction. Historically it was sold as Factrel (for diagnostic GnRH-stimulation testing) and Lutrepulse (pulsatile pump therapy for hypothalamic amenorrhea/infertility). In current peptide and men’s-health contexts it is most discussed as a testicular-stimulation / fertility-preservation agent during testosterone therapy.
Mechanism of Action
- GnRH receptor agonism on the pituitary (established) — binds gonadotrophs to release LH and FSH.
- Downstream HPG drive (established) — LH stimulates testosterone (Leydig cells) and ovarian steroidogenesis; FSH supports spermatogenesis and follicular development.
- Pulsatile vs continuous (established and clinically important) — intermittent pulses stimulate the axis (mimicking natural rhythm), while sustained continuous exposure desensitizes/suppresses it; this dual behavior underlies both fertility use and GnRH-agonist suppression in other contexts.
Limitations
Because the half-life is only minutes, a single injection produces a brief LH/FSH pulse. Sustained physiological stimulation historically required a pulsatile pump; intermittent subcutaneous self-injection (common off-label with TRT) does not perfectly replicate natural pulsatility, and long-term outcome data for that specific use is limited.
Evidence by Outcome
| Outcome | Evidence | Notes |
|---|---|---|
| Diagnostic GnRH-stimulation test (LH/FSH response) | Approved | Long-standing clinical use to assess pituitary/gonadal function |
| Pulsatile fertility therapy (hypothalamic amenorrhea) | Approved | Lutrepulse induced ovulation in a high proportion of patients |
| Maintaining testicular function during TRT | Clinical / Anecdotal | Common off-label use; mechanistically sound; limited dedicated trials |
| Restoring fertility / sperm production | Clinical | Plausible via LH/FSH stimulation; depends on intact pituitary-gonadal response |
| General “libido boost” in healthy users | Anecdotal | Indirect via testosterone; not a validated standalone use |
Reported Dosing
Not medical advice
Approved products used specific protocols (diagnostic bolus; pulsatile pump). Off-label TRT-adjunct figures below are community-reported only and not a clinical recommendation. See Reconstitution & Dosing Math and Injection Technique.
| Use | Dose | Frequency | Notes |
|---|---|---|---|
| Diagnostic test (historical) | ~100 µg | Single dose, measure LH/FSH response | IV or SC |
| Pulsatile fertility (Lutrepulse) | ~5–20 µg per pulse | Every ~90 min via pump | Mimics natural pulsatility |
| TRT adjunct (off-label/compounded) | ~100–200 µg | 2–3×/week to daily | Community protocols vary widely |
Pharmacokinetics
Very short half-life (~2–4 minutes) because native GnRH is rapidly degraded — which is exactly why pulsatile pump delivery was used for fertility, and why each injection produces only a short-lived LH/FSH pulse. (Long-acting GnRH agonists/antagonists are different, modified molecules.) See Half-Life & Pharmacokinetics.
Side Effects & Risks
- Generally well tolerated; injection-site reactions, headache, nausea, flushing, abdominal discomfort reported.
- Rare hypersensitivity/anaphylaxis has been reported with GnRH.
- With pulsatile fertility therapy, multiple gestation risk (ovulation induction).
- Effects depend on an intact pituitary-gonadal axis; it will not work if the pituitary or gonads cannot respond.
- Sourcing risk: compounded/research “gonadorelin” varies in identity and purity — see Sourcing and Red Flags & Scams.
- If used to manage the HPG axis, periodic Bloodwork & Monitoring (LH, FSH, testosterone/estradiol) is sensible; see Side Effects & Risk Management.
Cycling
No standardized “cycle.” In the TRT-adjunct context it is typically dosed intermittently and continuously alongside testosterone rather than cycled; pulsatile fertility use is a defined medical protocol. See Cycling.
Stacks It Appears In
- Frequently paired with testosterone therapy (TRT) to preserve testicular function/fertility (off-label).
- Conceptually related to Kisspeptin, which acts one step upstream of GnRH.
Comparisons
- Kisspeptin — kisspeptin acts upstream (on GnRH neurons); gonadorelin is GnRH and acts directly on the pituitary.
- Versus hCG: hCG mimics LH at the gonad (downstream of the pituitary); gonadorelin acts on the pituitary to release the body’s own LH/FSH — a more “upstream” approach to the same goal of maintaining testicular function.
Sourcing & Quality
With no branded US product currently marketed, supply is largely compounded or research-grade, so identity and purity vary. Evaluate critically: How to Read a CoA, Red Flags & Scams, Sourcing. Reconstitution and storage: Reconstitution & Dosing Math, Storage & Handling. No vendors are endorsed here.
Legal & Regulatory Status
(As of 2026-06-05.) Gonadorelin is a prescription drug and has a long approved history (e.g., Factrel for diagnostic testing; Lutrepulse for pulsatile fertility therapy). However, no branded FDA-approved gonadorelin product is currently marketed in the United States, and much present-day use is via compounding pharmacies and off-label, particularly as a TRT adjunct. Availability and legal status vary by country. See Regulatory & Legal Status.
FAQ
Is gonadorelin the same as GnRH? Yes — it is synthetic GnRH (LHRH), identical to the natural hormone.
Why is it used with testosterone therapy? Exogenous testosterone suppresses the body’s own LH, shrinking the testes and impairing fertility. Pulsed gonadorelin stimulates the pituitary to keep LH/FSH (and testicular function) going — an off-label role similar to hCG.
Is it FDA-approved? It was approved historically (Factrel, Lutrepulse), but no branded product is currently marketed in the US; current supply is largely compounded, and TRT-adjunct use is off-label.
Why such a short half-life and pulsatile dosing? Native GnRH is cleared in minutes, and pulsatile stimulation is what the axis responds to; continuous exposure actually suppresses it.
References
- U.S. FDA — historical labeling for Factrel (gonadorelin HCl, diagnostic) and Lutrepulse (gonadorelin acetate, pulsatile fertility therapy).
- Filicori M. et al. — pulsatile GnRH therapy and ovulation induction in hypothalamic amenorrhea.
- PubChem (CID 638793) — Gonadorelin chemical and pharmacological data.
- Reviews on GnRH physiology, pulsatile vs continuous signaling, and the HPG axis.
← Other Peptides · Home Educational information only — not medical advice. See Disclaimer.