Ipamorelin is among the most-searched compounds this publication covers. It is also, measured by the trials that exist, one of the least-studied — and the mismatch between those two facts is the whole story of this page.
This is research journalism. It contains no usage guidance, this site publishes no dose figures, and the dosing question is answered by Peptifact rather than here.
What it is
Ipamorelin is a synthetic pentapeptide — a five-amino-acid chain — that binds the growth hormone secretagogue receptor, the receptor for ghrelin. That places it in the ghrelin-agonist half of the growth hormone secretagogue class, alongside hexarelin, GHRP-2, GHRP-6 and the non-peptide MK-677.
Its reputation rests on selectivity. In preclinical characterisation, ipamorelin released growth hormone without the accompanying cortisol and prolactin elevations that the earlier GHRPs produced, and that finding is the origin of every "cleaner" claim made for it since. The finding is real. What it describes is an absence of unwanted effects, which is a different claim from a muscle effect, and the two get merged constantly in marketing copy.
The entire clinical record
Searched on ClinicalTrials.gov, 2026-09-08. Three registrations exist for ipamorelin. All three:
| Registration | Sponsor | Phase | Enrolled | Subject | Status |
|---|---|---|---|---|---|
| NCT00672074 | Helsinn Therapeutics (U.S.) | 2 | 117 | Postoperative ileus after bowel resection | Completed, published |
| NCT01280344 | Helsinn Therapeutics (U.S.) | 2 | 320 | Recovery of gastrointestinal function | Completed June 2013, no results posted |
| NCT07717866 | Axial Therapeutic Research | N/A | 52 | Multi-compound study | Active, not recruiting |
There is no fourth entry. No muscle trial, no strength trial, no body-composition trial, no athlete population, in any country, at any point. A compound bought overwhelmingly by people trying to add muscle has never once been registered to find out whether it does.
The one published result
The 117-patient study was published in International Journal of Colorectal Disease in 2014 as a prospective, randomised, double-blind, placebo-controlled, multicentre phase 2 proof-of-concept trial in adults undergoing open or laparoscopic bowel resection. The reasoning behind it was sound: ghrelin-receptor stimulation has promotility effects on the gut, and postoperative ileus is a real clinical problem without a good treatment.
The key efficacy endpoint was time from the first dose to tolerating a standardised solid meal. The result:
- Ipamorelin: 25.3 hours (median). Placebo: 32.6 hours. p = 0.15.
A seven-hour difference in the drug's favour that could not be distinguished from chance in a trial of that size — and, in the authors' words, "no significant differences between ipamorelin and placebo in the key and secondary efficacy analyses." Treatment-emergent adverse events occurred in 87.5% of the ipamorelin group and 94.8% of the placebo group, in a population recovering from abdominal surgery.
The paper's conclusion is a tolerability statement. The programme did not proceed to an approval, and the larger 320-patient follow-on completed in June 2013 with no results posted to the registry in the twelve years since. That absence is itself informative: sponsors reliably publish trials that work.
What this trial does and does not tell us. It does not tell us ipamorelin fails to build muscle — it was never asked that question, and the population was surgical patients, not lifters. What it tells us is that the only time this compound was put through a properly powered, blinded, placebo-controlled test against an objective endpoint, it did not separate from placebo, and its commercial development stopped there.
The literature is mostly about catching it
Of the 54 PubMed records returned for ipamorelin, a striking share are analytical chemistry papers on detecting the compound in urine — screening methods by liquid chromatography and mass spectrometry, metabolite characterisation, sample-stabilisation studies, and a 2015 paper measuring metabolites of GHRP-1, GHRP-2, GHRP-6, hexarelin and ipamorelin after nasal administration. Only two records are indexed as randomised controlled trials.
This is a pattern we have now recorded across several compounds in this category, and it is worth naming: for the injectable secretagogues, the anti-doping literature is larger and more recent than the clinical literature. More scientific effort has gone into detecting ipamorelin than into finding out what it does.
The practical consequence for a tested athlete is direct. Ipamorelin is prohibited under WADA section S2.2 at all times, in and out of competition, and validated detection methods have been in routine use for more than a decade. Our drug testing page covers the class in detail.
Regulatory status
Ipamorelin appears in category 2 of FDA's bulk drug substances lists — substances nominated for compounding that the agency identified as presenting significant safety risks. A category 2 listing is the reason a compound cannot be obtained lawfully from a compounding pharmacy in the United States and is instead sold labelled for research use.
It has no marketing approval in any jurisdiction we could identify. In this respect it differs from tesamorelin, the one member of the wider secretagogue class that holds a US approval — for abdominal fat reduction in HIV-associated lipodystrophy, not for muscle.
Where it sits on the ledger
On this site's evidence ledger, ipamorelin scores low, and this page is the reason why. Two randomised trials, both in the wrong population for the question, one negative and one unreported, no muscle endpoint anywhere in its history, a category 2 safety listing and a ban in tested sport.
That is not the same as saying it does nothing. It raises growth hormone; that is well characterised. It is saying that the entire distance between "raises growth hormone" and "builds muscle in a trained adult" is, for this compound, unmeasured — and it is a long distance, as the secretagogue class page and the comparison with anabolic steroids both set out.
Sources
- 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). PMID 25331030
- ClinicalTrials.gov registrations NCT00672074, NCT01280344, NCT07717866, retrieved 2026-09-08.
- Semenistaya E et al. Determination of growth hormone releasing peptides metabolites in human urine after nasal administration of GHRP-1, GHRP-2, GHRP-6, Hexarelin, and Ipamorelin. Drug Test Anal 2015. PMID 25869809
- WADA Prohibited List, section S2.2.
- FDA, Bulk Drug Substances Nominated for Use in Compounding — category 2.
- PubMed record counts retrieved 2026-09-08.