Ipamorelin: what the evidence shows

Ipamorelin

CNot approvedGH secretagogue

In one paragraphIpamorelin is a synthetic pentapeptide that stimulates growth-hormone release with relatively little effect on cortisol or prolactin. It was studied briefly in humans in the late 1990s and early 2000s, including for post-operative gut recovery, before development was discontinued. It is not an approved medicine, and the popular claims about body composition and sleep rest on very little human data.

Overall gradeC Weak

Human trialsFew, small

Outcomes graded2

Last reviewed1 September 2026

What the human research shows

Outcome	Grade	Effect size	Human studies	Where the evidence comes from
Growth hormone release	CWeak	Moderate	Small early-phase studies	Acute GH rise demonstrated in small human studies; long-term effects unstudied.1
Body composition	DNo human evidence	Not measurable	None controlled	No trial has measured it.

AMultiple good human trials, consistentBSome human trials, mostly consistentCFew or weak human studiesDAnimal or anecdotal onlyeffect size · red = adverse

Literature searched to 1 September 2026. Human studies only; animal and cell work informs the mechanism section and nothing else.

References

1
Raun K, et al. Ipamorelin, the first selective growth hormone secretagogue.Eur J Endocrinol, 1998;139:552–561Pharmacology; animal and early human data.