Ipamorelin is a synthetic pentapeptide, a molecule of five amino acids, which stimulates the growth hormone secretagogue receptor known as GHS-R1a and produces a pulsatile release of growth hormone. It is called “clean” because in a 1998 study it raised growth hormone much like GHRP-6, but without a statistically significant rise in cortisol and ACTH.
Selectivity does not mean, however, that ipamorelin is well studied. It has one completed human trial, and that trial failed. The wider context is covered in the pillar article on how peptides stimulate growth hormone release.
What is ipamorelin?
Ipamorelin is a peptide developed by Novo Nordisk in the late 1990s. It does not occur naturally in the body. It works through the same receptor as ghrelin, which is why it is classed as a growth hormone secretagogue rather than a GHRH analogue. It is sold as research material.
The difference from GHRH analogues is practical, not merely a matter of naming. A GHRH analogue mimics the body’s own hypothalamic hormone and tells the pituitary how much growth hormone to release. A secretagogue mimics ghrelin and opens the way for that release. That is why the two groups are paired, as described in the article on why CJC-1295 is combined with ipamorelin.
Why is ipamorelin called “clean” or “selective”?
The label comes from its hormonal profile. In a 1998 study, ipamorelin stimulated growth hormone release at a level comparable to GHRP-6 while producing no statistically significant rise in ACTH or cortisol. Selectivity here means the peptide moves one system without dragging the stress axis along with it.
The authors of that work called ipamorelin the first GHRP receptor agonist with a selectivity close to that of GHRH itself. That sentence is the source of the molecule’s later reputation. It is worth remembering what material it rested on: laboratory and animal work, not humans.
How does ipamorelin differ from GHRP-2 and GHRP-6?
The older compounds in the GHRP group, GHRP-2 and GHRP-6, stimulate growth hormone release but also raise cortisol and ACTH. Ipamorelin did not do so in the study cited. That is the main difference invoked by descriptions calling it a clean GHRP.
A second difference concerns appetite. GHRP-6 strongly stimulates hunger, which can be an advantage when building mass and an obstacle when cutting. The full map of differences in this group is gathered in the article on GHRP-2, GHRP-6, ipamorelin and hexarelin.
What do human studies of ipamorelin show?
As of April 2026 there is one completed human study. It was published by Beck and co-authors in 2014 in the International Journal of Colorectal Disease. It was a randomised, controlled study of postoperative ileus after bowel resection.
The study covered 114 patients who, for up to seven days after surgery, received ipamorelin at 0.03 mg per kilogram of body weight twice daily, or placebo. The median time to tolerating solid food was 25.3 hours in the ipamorelin group and 32.6 hours in the placebo group. The difference did not reach statistical significance, with a p value of 0.15.
The primary endpoint was therefore not met, and clinical development in that indication was halted. The dose quoted above comes from the protocol of that trial and is not a recommendation for anyone. Ipamorelin also has earlier animal work, including a 2009 study in a rat model of postoperative ileus, in which it accelerated intestinal transit.
What is not known about ipamorelin?
The list of unstudied things is longer than the list of studied ones. There are no completed studies assessing the effect of ipamorelin on body composition, muscle mass, bone density or recovery after exercise. Nor are there data on safety over many months of use.
That matters when reading descriptions promising specific physique results. The mechanism, the growth hormone pulse after administration, is described. The consequence of that pulse in a healthy adult after weeks of use has not been measured in a clinical trial.
Is ipamorelin legal?
Ipamorelin is not an approved medicine. In September 2023 the United States Food and Drug Administration placed it in category 2 of substances barred from compounded drugs for human use. It cannot be obtained legally in pharmaceutical form for human use in the United States. It also appears on the World Anti-Doping Agency list in category S2, prohibited in and out of competition.
There is no registered ipamorelin product in Poland or the European Union.
What is in the shop?
In our shop ipamorelin appears only as research material, in 10 mg vials, from three brands: Bio-Peptide, Genheal and Nouveaux Ltd.
There is also a ready-made combination with a GHRH analogue in one vial: Ipamorelin & CJC-1295 Combo 10 mg. The rest of the group is gathered in the growth hormone peptides category. The cart and the checkout are in English and prices are shown in Polish zloty.
Frequently asked questions
Why is ipamorelin called a clean GHRP?
Because in a 1998 study it stimulated growth hormone release without a significant rise in cortisol and ACTH, unlike GHRP-2 and GHRP-6.
Does ipamorelin have human studies?
One completed study from 2014 in 114 patients after bowel resection. It did not meet its primary endpoint, and the difference from placebo was not statistically significant.
Does ipamorelin build muscle?
No studies have tested that. No work has been published assessing the effect of ipamorelin on body composition, muscle mass or bone density.
How does ipamorelin differ from CJC-1295?
Ipamorelin acts through the ghrelin receptor, while CJC-1295 is a GHRH analogue acting through the growth hormone releasing hormone receptor. Both stimulate a growth hormone pulse, but by different pathways.
Does ipamorelin raise appetite like GHRP-6?
Descriptions of this molecule do not attribute a strong effect on hunger to it, unlike GHRP-6. No direct comparison of appetite in humans between the two peptides has been published.
Can ipamorelin be used in sport?
It cannot. Ipamorelin is on the World Anti-Doping Agency list in category S2 and is prohibited at all times.
Where this information comes from
The description of ipamorelin, the single completed human study as of April 2026 and its status with the United States Food and Drug Administration and the World Anti-Doping Agency come from material published by Superpower, version of 2 August 2026, checked on 31 August 2026.
The result of the 1998 study, including potency comparable to GHRP-6 and the absence of a rise in ACTH and cortisol above GHRH levels, comes from Raun K and co-authors, “Ipamorelin, the first selective growth hormone secretagogue”, European Journal of Endocrinology 1998, PMID 9849822. The human trial figures, that is 114 participants, the dose of 0.03 mg per kilogram twice daily, the medians of 25.3 against 32.6 hours and the p value of 0.15, come from Beck DE, Sweeney WB and McCarter MD in the International Journal of Colorectal Disease, 2014, PMID 25331030. The rat study comes from Venkova K and co-authors in the Journal of Pharmacology and Experimental Therapeutics, 2009, PMID 19289567. All three abstracts were read through Europe PMC on 7 September 2026.