Which has stronger evidence, Ipamorelin or GHRP-6?

Ipamorelin has stronger published evidence than GHRP-6: tier A (Controlled human trials) vs tier B (Small human studies). Ipamorelin: Randomized, placebo-controlled phase 2 trials in postoperative ileus were completed (no benefit shown); not approved. GHRP-6: Human data are limited to small pharmacological studies of GH release; no approved use. Tiers rate the strength of published evidence, not effectiveness.

Is Ipamorelin FDA-approved?

Ipamorelin is not FDA-approved.

How do Ipamorelin and GHRP-6 work?

Ipamorelin is a pentapeptide ghrelin receptor (GHS-R1a) agonist that stimulates growth hormone release from the anterior pituitary in a dose-dependent manner. GHRP-6 is a synthetic met-enkephalin-derived hexapeptide that activates the GHS-R1a ghrelin receptor on pituitary somatotrophs and hypothalamic arcuate nucleus neurons.

Comparison · Updated 2026-11-08

Ipamorelin VS GHRP-6

Short answer

Ipamorelin has stronger published evidence than GHRP-6: tier A (Controlled human trials) vs tier B (Small human studies).

Neither Ipamorelin nor GHRP-6 is FDA-approved.

Both are prohibited in sport by WADA under section S2.

Ipamorelin GHRP-6 Open in matchups

Side by side

Field	Ipamorelin PubChem CID 9831659	GHRP-6 PubChem CID 4345065
Evidence tier	A Tier A · Controlled human trials	B Tier B · Small human studies
Tier rationale	Randomized, placebo-controlled phase 2 trials in postoperative ileus were completed (no benefit shown); not approved.	Human data are limited to small pharmacological studies of GH release; no approved use.
FDA status	Not approved	Not approved
Other approvals	None listed	None listed
WADA	Prohibited · S2Peptide hormones, growth factors, related substances and mimetics	Prohibited · S2Peptide hormones, growth factors, related substances and mimetics
Family	GH & Growth	GH & Growth
Residues	Not on file	Not on file
Molecular weight	Not on file	Not on file
Formula	Not on file	Not on file
Discovered	1998Described by Novo Nordisk as a selective GH secretagogue.	1984Described by Bowers and colleagues as a synthetic GH-releasing hexapeptide.
Routes studied	Subcutaneous, Intramuscular	Subcutaneous, Intramuscular
Mechanism	Ipamorelin is a pentapeptide ghrelin receptor (GHS-R1a) agonist that stimulates growth hormone release from the anterior pituitary in a dose-dependent manner. Unlike other GHRPs, it has high selectivity for GH release without significantly elevating ACTH, cortisol, or prolactin, making it the cleanest GHRP available.	GHRP-6 is a synthetic met-enkephalin-derived hexapeptide that activates the GHS-R1a ghrelin receptor on pituitary somatotrophs and hypothalamic arcuate nucleus neurons. It triggers GH release via inositol triphosphate/protein kinase C signaling and also potently stimulates gastric motility and appetite through vagal afferent activation.
Safety notes	Well-tolerated in Phase II clinical trials.	Extensively studied in humans.
Cited studies	0 studies	0 studies

Questions

Which has stronger evidence, Ipamorelin or GHRP-6?: Ipamorelin has stronger published evidence than GHRP-6: tier A (Controlled human trials) vs tier B (Small human studies). Ipamorelin: Randomized, placebo-controlled phase 2 trials in postoperative ileus were completed (no benefit shown); not approved. GHRP-6: Human data are limited to small pharmacological studies of GH release; no approved use. Tiers rate the strength of published evidence, not effectiveness.
Is Ipamorelin FDA-approved?: Ipamorelin is not FDA-approved.
Is GHRP-6 FDA-approved?: GHRP-6 is not FDA-approved.
Are Ipamorelin and GHRP-6 banned in sport?: Both are prohibited in sport by WADA under section S2.
How do Ipamorelin and GHRP-6 work?: Ipamorelin is a pentapeptide ghrelin receptor (GHS-R1a) agonist that stimulates growth hormone release from the anterior pituitary in a dose-dependent manner. GHRP-6 is a synthetic met-enkephalin-derived hexapeptide that activates the GHS-R1a ghrelin receptor on pituitary somatotrophs and hypothalamic arcuate nucleus neurons.