GHRP-6 vs Ipamorelin
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.
GHRP-6
GHRP-6 is a first-generation synthetic hexapeptide GH secretagogue that strongly stimulates pituitary GH release via ghrelin receptor activation. It is one of the oldest and most well-studied GHRPs, with a large body of research spanning more than three decades. GHRP-6 produces significant GH pulses but is notable for powerfully stimulating appetite — a side effect that can be beneficial for those in a caloric deficit or disadvantageous for those managing body composition.
Full profileIpamorelin
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 profile| GHRP-6 | Ipamorelin | |
|---|---|---|
| Category | Performance & Growth Hormone | Performance & Growth Hormone |
| Also known as | Growth Hormone Releasing Peptide-6, His-D-Trp-Ala-Trp-D-Phe-Lys-NH2 | NNC 26-0161, Ipamorelin acetate |
| Evidence | Preclinical only | Investigational (in trials) |
| Dosing range | 100mcg–300mcg mcg, 1–3 times daily, on an empty stomach | 100mcg–300mcg mcg, 1–3x daily (typically pre-sleep and/or pre-workout) |
| Administration | Subcutaneous injection, Intramuscular injection | Subcutaneous injection, Intramuscular injection |
| Key side effects | Strong increase in appetite (most common and notable), Elevated cortisol and prolactin at higher doses, Water retention / bloating, Fatigue at high doses | Water retention (mild), Tingling / numbness in extremities, Increased appetite, Headache (transient) |
| Cited sources | 3 references | 3 references |
Key differences
- Evidence level differs: GHRP-6 is preclinical only, while Ipamorelin is investigational (in trials).
- Frequency: GHRP-6 is typically 1–3 times daily, on an empty stomach; Ipamorelin is 1–3x daily (typically pre-sleep and/or pre-workout).
How each works
GHRP-6
Human studies confirm GHRP-6 robustly elevates GH within 15–30 minutes of injection, with effects diminishing toward baseline within 2–3 hours. Chronic use increases baseline IGF-1. Research also indicates mild stimulation of cortisol and prolactin, particularly at higher doses. Animal models have shown potential cardioprotective, hepatoprotective, and muscle-sparing effects, though human equivalents are not established.
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.
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.