GHRP-6 and ipamorelin are both GHRPs — growth-hormone-releasing peptides that act on the ghrelin receptor to trigger a GH pulse. They're often compared because they represent two generations of the same idea. GHRP-6 is the older, more potent-but-messier option: it strongly releases GH but also markedly increases appetite and can nudge cortisol and prolactin. Ipamorelin is the newer, more selective choice, designed to deliver the GH pulse with minimal appetite or hormonal "noise."
At a glance
| GHRP-6 | Ipamorelin | |
|---|---|---|
| Class | GHRP (ghrelin-receptor agonist) | GHRP (ghrelin-receptor agonist) |
| Appetite effect | Strong increase in hunger | Minimal |
| Cortisol / prolactin | Can increase | Minimal effect |
| Selectivity | Less selective | Highly selective |
| Generation | Earlier GHRP | Newer, 'cleaner' GHRP |
| FDA status | Not approved (research chemical) | Not approved (research chemical) |
| Sport status | Banned (WADA) | Banned (WADA) |
The bottom line
Bottom line: Same receptor, different temperament. GHRP-6 releases growth hormone strongly but comes with a big hunger spike and more hormonal side effects; ipamorelin is the selective successor that aims for the GH pulse alone. The strong appetite stimulation of GHRP-6 is sometimes sought deliberately — but neither peptide is approved, and both are banned in sport.
Frequently asked questions
What is the main difference between GHRP-6 and ipamorelin?
Both are GHRPs that release growth hormone, but GHRP-6 strongly increases appetite and can raise cortisol and prolactin, while ipamorelin is far more selective with minimal effect on those.
Does GHRP-6 make you hungry?
Yes — GHRP-6 is well known for strongly stimulating appetite via the ghrelin receptor. Ipamorelin was designed to avoid this, producing a growth-hormone pulse with minimal hunger effect.
Which is 'cleaner', GHRP-6 or ipamorelin?
Ipamorelin is considered the cleaner, more selective peptide because it triggers growth hormone with little impact on appetite, cortisol or prolactin. Neither is FDA-approved, and both are banned in sport.
References
Combined peer-reviewed sources from both peptide guides. Inclusion is not endorsement.
- Howard AD, Feighner SD, Cully DF, et al. A receptor in pituitary and hypothalamus that functions in growth hormone release. Science. 1996. Peer-reviewed study
- Frago LM, Paneda C, Argente J, Chowen JA. GHRP-6 increases IGF-I mRNA and activates Akt in RCA-6 cells. J Neuroendocrinol. 2005. Peer-reviewed study
- Pombo M, Leal-Cerro A, Barreiro J, et al. Growth hormone releasing hexapeptide-6 (GHRP-6) test in the diagnosis of GH-deficiency. J Pediatr Endocrinol Metab. 1996. Peer-reviewed study
- Zhao X, Pan K, Li R, et al. Growth hormone-releasing peptide 6 (GHRP-6) hydrogel for acute kidney injury therapy via metabolic regulation. J Nanobiotechnology. 2025. Peer-reviewed study
- Berlanga-Acosta J, Cibrian D, Valiente-Mustelier J, et al. Growth hormone releasing peptide-6 (GHRP-6) prevents doxorubicin-induced myocardial and extra-myocardial damages by activating prosurvival mechanisms. Front Pharmacol. 2024. Peer-reviewed study
- Yu AP, Pei XM, Sin TK, et al. [D-Lys3]-GHRP-6 exhibits pro-autophagic effects on skeletal muscle. Mol Cell Endocrinol. 2015. Peer-reviewed study
- Raun K, Hansen BS, Johansen NL, et al. Ipamorelin, the first selective growth hormone secretagogue. Eur J Endocrinol. 1998. Peer-reviewed study
- Sinha DK, Balasubramanian A, Tatem AJ, et al. Beyond the androgen receptor: growth hormone secretagogues in the management of body composition in hypogonadal males. Transl Androl Urol. 2020. Peer-reviewed study
- Johansen PB, Nowak J, Skjaerbaek C, et al. Ipamorelin, a new growth-hormone-releasing peptide, induces longitudinal bone growth in rats. Growth Horm IGF Res. 1999. Peer-reviewed study
- Lu Z, Ngan MP, Liu JYH, et al. The growth hormone secretagogue receptor 1a agonists, anamorelin and ipamorelin, inhibit cisplatin-induced weight loss in ferrets: Anamorelin also exhibits anti-emetic effects via a central mechanism. Physiol Behav. 2024. Peer-reviewed study
- Gouda M, Ganesh CB. The influence of ghrelin agonist ipamorelin acetate on the hypothalamic-pituitary-testicular axis in a cichlid fish, Oreochromis mossambicus. Anim Reprod Sci. 2024. Peer-reviewed study
- Gobburu JV, Agersø H, Jusko WJ, et al. Pharmacokinetic-pharmacodynamic modeling of ipamorelin, a growth hormone releasing peptide, in human volunteers. Pharm Res. 1999. Peer-reviewed study