Ipamorelin vs Melanotan II
A neutral, side-by-side comparison of two performance & growth hormone peptides — their mechanisms, dosing ranges, administration routes, side effects, and research evidence. For research and educational purposes only.
Ipamorelin
Ipamorelin is a selective growth hormone secretagogue (GHS) and ghrelin receptor agonist. It stimulates GH release with high selectivity — minimal cortisol or prolactin elevation compared to older GHRPs. Widely used in research protocols for body composition, sleep quality, and recovery.
Full profileMelanotan II
Melanotan II (MT-II) is a cyclic lactam analog of alpha-melanocyte stimulating hormone (α-MSH) that acts as a potent, non-selective melanocortin receptor agonist (MC1R, MC3R, MC4R, MC5R). Developed at the University of Arizona in the late 1980s, it produces eumelanin-driven skin darkening (tanning) via MC1R, sexual arousal and spontaneous erections via MC4R, and appetite suppression via MC3R/MC4R. Bremelanotide (PT-141) — now FDA-approved for female sexual dysfunction — was derived from Melanotan II.
Full profile| Ipamorelin | Melanotan II | |
|---|---|---|
| Category | Performance & Growth Hormone | Performance & Growth Hormone |
| Also known as | NNC 26-0161, Ipamorelin acetate | MT-II, MTII, Cyclo[Nle4,D-Phe7]-α-MSH |
| Evidence | Investigational (in trials) | Research-stage |
| Dosing range | 100mcg–300mcg mcg, 1–3x daily (typically pre-sleep and/or pre-workout) | 250mcg–1000mcg mcg, Daily during loading phase; 2–3x weekly for maintenance |
| Administration | Subcutaneous injection, Intramuscular injection | Subcutaneous injection (most common), Intranasal (less effective, lower bioavailability) |
| Key side effects | Water retention (mild), Tingling / numbness in extremities, Increased appetite, Headache (transient) | Nausea (most common — especially first 30–60 minutes post-injection), Facial flushing, Spontaneous erections (males — often unwanted at higher doses), Fatigue / yawning post-injection |
| Cited sources | 3 references | 3 references |
Key differences
- Evidence level differs: Ipamorelin is investigational (in trials), while Melanotan II is research-stage.
- Administration: Ipamorelin — Subcutaneous injection, Intramuscular injection; Melanotan II — Subcutaneous injection (most common), Intranasal (less effective, lower bioavailability).
- Frequency: Ipamorelin is typically 1–3x daily (typically pre-sleep and/or pre-workout); Melanotan II is Daily during loading phase; 2–3x weekly for maintenance.
How each works
Ipamorelin
Ipamorelin selectively stimulates GH release via the ghrelin receptor (GHS-R1a) without significantly elevating ACTH or cortisol — the feature that distinguishes it from GHRP-6 and GHRP-2 (Raun et al., 1998, in swine/rodent models). Human data are limited: a PK study in 40 volunteers established a ~2-hour half-life (Gobburu et al., 1999), and a Phase 2 trial for postoperative ileus (Beck et al., 2014) failed its primary endpoint. It is not FDA-approved, and claims about body composition or recovery are extrapolated from GH physiology, not human outcome trials.
Melanotan II
Melanotan II's broad melanocortin receptor agonism produces a constellation of effects across multiple systems. MC1R activation in melanocytes upregulates tyrosinase, the rate-limiting enzyme in melanin synthesis, producing UV-independent skin darkening. MC4R activation in the CNS and spinal cord drives sexual arousal and erectogenic effects more potent than most PDE5 inhibitors, and also produces appetite suppression and reduced food intake (the same pathway exploited by weight-loss drugs targeting the melanocortin system). MC3R activation contributes to energy homeostasis effects.
This comparison aggregates public research and structured profile data for informational purposes only. It is not medical advice and does not recommend either compound for human use. Consult a qualified healthcare provider before considering any peptide.