Ipamorelin
Aliases: NNC 26-0161
Last verified: 2026-09-23
The short version
Ipamorelin is the most selective of the GHRP peptides: it stimulates pulsatile growth hormone release via ghrelin receptors (GHS-R1a) with almost no effect on cortisol, prolactin or ACTH. In human trials it confirmed dose-dependent increases in GH and IGF-1 without significant adverse effects in short protocols — but those trials are small and short; long-term safety and clinical benefit are not established. It is not approved as a drug anywhere; it is used in 'wellness' clinics paired with CJC-1295.
Identity & type
- Molecular type
- analog
- Sequence / structure
- Aib-His-D-2-Nal-D-Phe-Lys-NH2 (pentapeptid)
- Molecular weight
- ~711 Da
- Origin
- Synthetic pentapeptide growth hormone secretagogue (GHRP) of the fifth generation; derived from earlier GHRP peptides.
Mechanism of action
Ghrelin/GHS-R1a receptor agonist in the pituitary, stimulating pulsatile (physiological) GH release.
not confirmed in humans
Dosing & routes
Official / clinical context
Development was abandoned; no active regulatory document exists. There are no official indications.
Regulator-approved labeling and published study designs — never a recommendation.
Community-reported practice
Typically 100–300 mcg SC 1–3× daily, often at night; frequently stacked with CJC-1295 no-DAC. Most reported effects: deeper sleep (especially first half of the night), better recovery between workouts, gradual body-composition improvement over 8–12 weeks. No hunger surge (unlike GHRP-6).
Unverified self-reports. Not medical advice. Not endorsement.
Expected effects (community)
Most reported effects: deeper sleep (especially first half of the night), better recovery between workouts, gradual body-composition improvement over 8–12 weeks. No hunger surge (unlike GHRP-6).
Protocol — official vs community
Official / label
No approved product. Studied in clinical research as a selective GHRP at 0.03 mg/kg SC single doses.
Duration: Single-dose study designs; no chronic official protocol exists.
Its selectivity (GH release without meaningful cortisol/prolactin spikes) is what survived scrutiny.
Community (anecdotal)
100–300 mcg SC 1–3× daily, most often at night; the standard stack partner is CJC-1295 no-DAC (Mod GRF).
- Cycle:
- 8–12 weeks typical, sometimes up to 16.
- Break:
- 4 weeks off — community logic: avoid desensitization of the GHS-R pathway.
The desensitization rationale is plausible (receptor internalization) but never demonstrated in humans for ipamorelin specifically.
Human evidence
Small controlled trials (8–12 weeks) confirm dose-dependent GH/IGF-1 response and good tolerability; no large RCTs with clinical outcomes (sleep quality, body composition).
Preclinical evidence
Animal studies show a selective GH response without hormonal 'noise'; data on bone and muscle anabolism are limited.
Known risks
- Nausea, headache, injection-site redness (rare)characterized
- Theoretical acromegaloid concern with chronic usetheoretical
- Unknown effects in children and pregnancycharacterized
Teal: characterized in clinical/labeling contexts. Amber: theoretical or reported outside controlled settings.
Unknowns & evidence gaps
- Long-term safety and clinical benefit
- Optimal human dosing schedule
Frequently asked questions
References
- Raun K. et al., ipamorelin — selective GH secretagogue (Eur J Endocrinol, 1998)
- Intranasal and SC ipamorelin studies in healthy subjects (J Clin Endocrinol Metab, 2000s)