Published by Pinnacle Pulse, maker of a self-tracking app. We have no affiliate or sales relationship with any peptide seller. Editorial policy →

Ipamorelin: what the research shows, and what it doesn’t

By Pinnacle Pulse Editorial Team · Status as of 16 October 2026 · Next scheduled update: 14 January 2027

Short answer: Ipamorelin is a five-amino-acid peptide that makes the pituitary release growth hormone, developed by Novo Nordisk in the 1990s. In humans it was tested in a dosing study in healthy men and in one phase 2 trial after bowel surgery, where it worked no better than placebo. It is not an approved medicine, and FDA has flagged safety concerns.

What ipamorelin is

Ipamorelin belongs to the growth hormone secretagogues, compounds that act on the receptor now known to respond to ghrelin, the hunger hormone made in the stomach. It is a pentapeptide, five amino acids long, and two of them are not ones the body makes. Its sequence runs Aib-His-D-2-Nal-D-Phe-Lys-NH2.

Chemists at Novo Nordisk in Måløv, Denmark, arrived at it by trimming down GHRP-1, an earlier peptide in the same family, and published the result in 1998 in the European Journal of Endocrinology under the title “Ipamorelin, the first selective growth hormone secretagogue”. “Selective” is the word you’ll see repeated, so it is worth looking at what it rested on.

What has been studied

The selectivity claim, in pigs

In conscious swine, ipamorelin released growth hormone about as well as GHRP-6. The interesting part was what it didn’t do. GHRP-6 and GHRP-2 also pushed up ACTH and cortisol, the stress-hormone pair. Ipamorelin did not, even at doses more than 200 times what was needed for the growth hormone effect. None of the three changed the reproductive hormones, prolactin or thyroid-stimulating hormone. That is a finding in pigs. The paper ended by calling ipamorelin a “very interesting candidate” for clinical development.

Healthy volunteers

A 1999 study in Pharmaceutical Research gave intravenous infusions at five dose levels to healthy men, eight per level. Growth hormone rose in a single burst, peaking at about 40 minutes, then fell away. The half-life of the peptide itself was about two hours. This was a pharmacology study. It wasn’t designed to look for benefits and didn’t report any.

The trial that tested a use

The real test came much later and had nothing to do with muscle or anti-aging. Ghrelin speeds up the gut, so a multicentre US team led from the Ochsner Clinic in New Orleans asked whether ipamorelin could shorten postoperative ileus, the stall in bowel function that follows abdominal surgery. Their phase 2 trial, randomized, double-blind and placebo-controlled, enrolled 117 adults having bowel resections, of whom 114 were analysed. Ipamorelin or placebo went in intravenously for up to a week.

It didn’t work. Patients on ipamorelin reached their first tolerated solid meal at a median of 25.3 hours versus 32.6 on placebo, a difference the statistics could not separate from chance, and none of the secondary measures differed either. Adverse events were common in both groups, 87.5 percent with ipamorelin and 94.8 percent with placebo, which is what you’d expect after major surgery. The authors called it well tolerated.

That trial, published in 2014, is one of only two PubMed returns when we searched on 16 October 2026 for ipamorelin limited to clinical trials or randomized trials. The other is the 1999 dosing study.

What the research does not show

There is no published trial of ipamorelin for muscle, fat loss, sleep, recovery or aging. People who use it for those reasons are relying on the pig study and on the logic of "more growth hormone", which isn't the same as evidence.

The “selective, no cortisol” reputation comes from animals. We did not find a human study designed to confirm it.

There are no long-term safety data in anyone. The longest exposure in a trial was about a week, in hospital.

And FDA’s reading of the safety record is more cautious than the surgeons’ summary. The agency says that “a study published in literature identified serious adverse events including death when ipamorelin was administered intravenously for improving gastric motility”. It doesn’t name the study, and the abstract of the 2014 trial doesn’t report deaths. The agency also points to possible immune reactions and to the unnatural amino acids, which make the product harder to characterize.

Status as of 16 October 2026. EU and US: not an authorized medicine (no entry in EMA’s medicines data or in Drugs@FDA). FDA has placed ipamorelin acetate in category 2 of its 503B interim policy for outsourcing facilities (since 29 September 2023), meaning it may present significant safety risks. WADA: the 2027 Prohibited List names ipamorelin under S2.2.4 (growth hormone secretagogues), prohibited at all times.

FAQ

What makes ipamorelin different from GHRP-6?

In a 1998 study in pigs, ipamorelin released growth hormone without raising ACTH or cortisol, while GHRP-6 raised both. Whether that holds in humans has not been established in a dedicated trial.

Was ipamorelin ever tested as a treatment?

Yes, once in a phase 2 trial for bowel function after abdominal surgery. It did not shorten the time to a tolerated meal compared with placebo.

Why is FDA concerned about ipamorelin?

FDA cites possible immune reactions, unnatural amino acids that complicate characterization, and a published report of serious adverse events including death with intravenous use for gastric motility. It says it lacks safety information for other injectable routes.

Sources

  • Raun K, et al. Ipamorelin, the first selective growth hormone secretagogue. Eur J Endocrinol. 1998;139(5):552-61. PMID 9849822
  • Gobburu JV, et al. Pharmacokinetic-pharmacodynamic modeling of ipamorelin, a growth hormone releasing peptide, in human volunteers. Pharm Res. 1999;16(9):1412-6. PMID 10496658
  • Beck DE, et al. Prospective, randomized, controlled, proof-of-concept study of the ghrelin mimetic ipamorelin for the management of postoperative ileus in bowel resection patients. Int J Colorectal Dis. 2014;29(12):1527-34. PMID 25331030 (checked 16 October 2026)
  • PubMed search “ipamorelin AND (clinical trial[pt] OR randomized controlled trial[pt])”, run 16 October 2026 via NCBI E-utilities: 2 records.
  • FDA. Certain bulk drug substances for use in compounding that may present significant safety risks (content current as of 22 April 2026). fda.gov
  • WADA. 2027 Prohibited List, class S2.2.4. wada-ama.org
  • EMA. Download medicine data: table of all medicines assessed by EMA (Excel), checked 16 October 2026. ema.europa.eu
  • FDA. Drugs@FDA, database of FDA-approved drugs, checked 16 October 2026. accessdata.fda.gov

Facts last checked: 16 October 2026.

About this article

Written by: the Pinnacle Pulse Editorial Team, the people who make the Pinnacle Pulse app. We work only from primary sources such as regulators, legal texts, trial registries and PubMed, and we remove claims we can’t check against one.

This article has not been reviewed by a physician. It is general information, not medical advice.

Spotted an error? Our editorial policy explains how to report it and how we correct mistakes.

Change log

  • 16 October 2026: First published.

From the makers of this site: Pinnacle Pulse is a neutral tracking app. We don’t sell or recommend any substance. About Pinnacle Pulse

This article is for general information only. It is not medical advice and does not recommend the use of any substance. Decisions about medicines belong with a qualified healthcare professional.