Ipamorelin guide
Most compounds in this library are under-researched. Ipamorelin is the opposite: it is a finished pharmaceutical programme that did not work. A company developed it, ran two phase 2 trials, missed the primary endpoint in the one that was published, and stopped89. In 2024 an FDA advisory committee voted 0 in favour and 12 against allowing pharmacies to compound with it3.
The short answer
- What it is: a five-amino-acid peptide that prompts the pituitary gland to release a burst of growth hormone.
- Approved? No, nowhere, and development was abandoned rather than unfinished12.
- Published human evidence: two papers. One 1999 pharmacology study and one 2014 trial that missed its endpoint816.
- Does it raise growth hormone in people? Yes, in one burst that is gone within six hours, measured once, intravenously, in 199910.
- Evidence for the subcutaneous route it is sold for: none at all. FDA says so directly2104.
- In sport: named on the prohibited list, banned at all times720.
What happened when it was actually tested
The trial was for post-operative ileus, the sluggish gut that follows bowel surgery. It made sense: a rat study had shown repeated dosing improved gut recovery816. A hundred and seventeen patients were enrolled into a double-blind, placebo-controlled, multicentre trial, and the measure was how long it took to tolerate a solid meal.
Ipamorelin came in at a median of 25.3 hours against 32.6 hours for placebo. That looks like a win until you see the p value, which was 0.15. The paper states plainly that there were no significant differences from placebo on the key or any secondary measure.
The safety numbers are not in the abstract, and they matter. FDA extracted them in its own review: more low potassium on ipamorelin than placebo, more insomnia, more raised blood sugar at discharge817. And two patients in the ipamorelin arm died, with none reported in the placebo arm84. Read that carefully: the trial was small, it was not powered to measure deaths, both patients had surgical complications with a known background rate, and FDA itself says it is unclear whether the deaths were related to the drug. It is a signal, not a verdict. FDA still cites it as a reason for concern in its compounding listing4.
The trial nobody has ever seen
There was a second phase 2 trial. It enrolled 320 patients, nearly three times the size of the published one, tested three dose levels against placebo, and completed in 2014. Its registry entry still shows no results posted, and it has never been published anywhere9.
Nothing can be concluded from it, in either direction. But it is worth knowing that the largest body of human data on this compound exists, was collected, and has never been shown to anyone. Shortly afterwards, the programme was discontinued.
What the 2024 review found
Two compounding pharmacies nominated ipamorelin to be added to the list of substances pharmacies may legally compound with. FDA reviewed it and found no data supporting effectiveness for growth hormone deficiency, and none for post-operative ileus23. It also found that the substance is not well characterised chemically, and that the certificate of analysis supplied to it lacked tests for impurities, aggregates and bacterial endotoxins2.
FDA recorded what ipamorelin was being marketed for: weight loss, anti-ageing, inflammatory conditions, sleep and bodybuilding2. Not one of those has been tested in a person.
The committee voted twice, once on each chemical form. Both votes were 0 yes, 12 no, 1 abstain3. The recorded discussion includes a member noting that how often a drug is prescribed does not make it safe or effective.
The selectivity claim, traced to its source
Ipamorelin is sold on the idea that it raises growth hormone cleanly, without the cortisol and prolactin rise that other peptides in its class cause. That claim is real and it has a source: a 1998 paper titled, in so many words, the first selective growth hormone secretagogue11.
Three things about that source. Its authors were the research department of the company that developed the molecule. The selectivity result came from acute hormone measurements in conscious pigs. And prolactin was unchanged by every peptide tested, including the comparators, so prolactin does not distinguish ipamorelin from anything. The finding that does distinguish it, on the stress hormones, has never been replicated independently and has never been measured in a human being.
That is not a reason to assume the claim is false. It is a reason to know it rests on pigs and on a single interested source, which is not how it is usually presented.
Muscle, fat and sleep: where the evidence actually points
No human study has ever measured muscle, fat or body composition after ipamorelin12. Neither of the two human papers looked. The animal data that does exist runs against the marketing: in mice, ipamorelin increased body fat and increased food intake, while growth hormone itself reduced fat12.
On bone, a rat study reported increased bone mineral content, which is the finding the title carries. Corrected for the animals being bigger, the increase disappeared, and bone density by volume was unchanged1314.
On sleep, there is no study at all, in any species8. The only human sleep-related number that exists points the other way: insomnia was about twice as common on ipamorelin as on placebo in the trial.
IGF-1, the hormone usually invoked to explain what growth hormone secretagogues do, has never been measured in a person given ipamorelin, and the animal results contradict each other14.
Does the effect last?
This is an open question with a specific experimental basis. After three weeks of treatment in rats, the pituitary cells that make growth hormone held less of it than in untreated animals15. FDA raises the same concern in its review, warning that prolonged exposure may not keep producing a hormone response.
The only human measurement is a single infusion in 1999. Nobody has measured what happens on the second week, or the second month, or by any route other than intravenous10.
What is in the vial
Two forensic laboratories, working independently in different countries, analysed seized material sold as ipamorelin and found it was not ipamorelin. It was a modified version carrying an extra amino acid at one end — a different molecule under the same name1819.
Separately, eighteen recalls name ipamorelin, across ten compounding firms, and every single one was for sterility: either no assurance of it or manufacturing deviations that called it into question6. Many of those products were combinations, pairing ipamorelin with sermorelin or CJC-1295 in the same vial65, which is also how most of it is sold today. A combination makes any individual effect impossible to attribute.
The class concern
FDA’s safety reasoning is inherited rather than specific. Growth hormone secretagogues raise growth hormone, which raises IGF-1, and every approved growth hormone product carries label warnings about tumours, glucose intolerance and diabetes, fluid retention and raised pressure inside the skull2. FDA’s position is that there is not enough information to conclude ipamorelin avoids those concerns.
It also notes that injecting under the skin is generally more likely to provoke an immune response than injecting into a vein4. All the human trial data is intravenous. The route people use is the other one.
Where the rest of the detail lives
The interactive library on the homepage carries the fuller reference entry for ipamorelin, including the amounts and handling notes it holds for every compound. That is general reference information, the same for every visitor.
References
These are the sources behind this page, listed so you can read them yourself rather than take our word for it. Animal and laboratory findings do not establish that something works or is safe in people. Doses and protocols shown on a study card are that study's research parameters, not recommendations. PepCaddie does not sell peptides and does not choose a dose for anyone; this is educational material and it does not replace a qualified healthcare professional.
The phase 2 trial that missed its endpoint
2014Human randomised trial
The dose above is the amount used in this study. It is research information, not a recommended dose, and PepCaddie does not convert study doses into human doses.
Median time to a first tolerated meal was 25.3 hours on ipamorelin against 32.6 hours on placebo, and that difference did not reach statistical significance. The paper states directly that there were no significant differences between ipamorelin and placebo in the key or secondary efficacy analyses. FDA’s review of the same trial adds figures the abstract omits: more hypokalaemia on ipamorelin, more insomnia, more hyperglycaemia at discharge, and two fatal serious adverse events in the ipamorelin arm with none reported in placebo.
Limitation: The authors describe it as a small proof-of-concept study in patients with a broad range of conditions. It was not powered to measure mortality, and FDA itself says whether the deaths related to ipamorelin is unclear. The favourable signal in one surgical subgroup is a post-hoc analysis and can only generate a hypothesis.
Multicentre, double-blind, placebo-controlled phase 2 trialView study: The phase 2 trial that missed its endpoint
The 320-patient trial that never reported
2014Registered clinical trial
The dose above is the amount used in this study. It is research information, not a recommended dose, and PepCaddie does not convert study doses into human doses.
This trial was almost three times the size of the published one, tested three dose levels against placebo, and completed in 2014. Its registry record still shows no results posted, and no publication of it exists in the literature. It is the largest block of human ipamorelin data in existence and nobody outside the sponsor knows what it found.
Limitation: Nothing can be inferred from an unreported trial, in either direction. Its silence is a fact about the evidence base rather than evidence about the drug.
Phase 2, randomised, quadruple-masked, placebo-controlled, three dose levelsView study: The 320-patient trial that never reported
The only human pharmacology study, from 1999
1999Human randomised trial
The dose above is the amount used in this study. It is research information, not a recommended dose, and PepCaddie does not convert study doses into human doses.
Ipamorelin released growth hormone at every dose tested, in a single burst peaking at about 40 minutes and falling to negligible levels by six hours. Its own half-life was about two hours and its handling was dose-proportional. The variability between individuals in the hormone response was larger than in the drug levels. This is the only study that has ever measured what ipamorelin does in a person’s bloodstream.
Limitation: Healthy young men with intact hormone systems, one intravenous infusion each, in 1999. Nothing here describes repeated dosing, the subcutaneous route everything is sold for, women, or any patient group. The sample size in the published abstract and in FDA’s account of the same study do not reconcile.
Randomised, placebo-controlled dose escalationView study: The only human pharmacology study, from 1999
The source of the selectivity claim
1998Animal studyNot human evidence
The paper that named ipamorelin and made the claim everything else repeats. In pigs, ipamorelin released growth hormone without raising the stress hormones ACTH and cortisol, even at doses more than 200 times higher than those needed for the hormone effect, whereas two comparator peptides did raise them. The authors describe the result as very surprising.
Limitation: The selectivity finding is acute hormone measurement in conscious pigs, in a single paper from the manufacturer’s own research department, never independently replicated, and never tested in a human. Prolactin was unchanged by every peptide tested, so it does not distinguish ipamorelin from the others.
Laboratory and animal characterisation studyView study: The source of the selectivity claim
In mice, it increased body fat
2001Animal studyNot human evidence
Ipamorelin increased fat pad weight relative to body weight and increased relative body fat measured by scanning, in both hormone-deficient and normal mice. Growth hormone itself did the opposite. Food intake and the appetite hormone leptin both rose. The result runs directly against the fat-loss claim made for this compound.
Limitation: Mice, with doses not stated in the published record. Because food intake rose too, the fat gain may be driven by appetite rather than by a direct effect on fat tissue.
Controlled animal study with body composition scanningView study: In mice, it increased body fat
Bone gains that vanish once corrected for weight
2000Animal studyNot human evidence
The dose above is the amount used in this study. It is research information, not a recommended dose, and PepCaddie does not convert study doses into human doses.
Bone mineral content rose, which is the headline the title carries. Corrected for the increase in body weight it was unchanged, and bone density by volume was unchanged too. The bones got bigger because the animals got bigger, rather than becoming denser.
Limitation: Seven rats in the treated group, over twelve weeks. It is a useful illustration of how a true headline and a true correction can point in different directions, and of why the corrected figure matters.
Controlled animal study with continuous infusionView study: Bone gains that vanish once corrected for weight
Bone growth in rats, with no change in IGF-1
1999Animal studyNot human evidence
The dose above is the amount used in this study. It is research information, not a recommended dose, and PepCaddie does not convert study doses into human doses.
Bone growth rate and body weight both rose with dose over fifteen days. Notably, total IGF-1, the binding proteins and the blood markers of bone turnover were all unaffected, which complicates the usual explanation that these peptides work by raising IGF-1. The authors concluded the finding required demonstration in future clinical studies.
Limitation: Adult rats over fifteen days, in work from the manufacturer’s own laboratory. The clinical studies the authors called for were never done for growth.
Dose-ranging controlled animal studyView study: Bone growth in rats, with no change in IGF-1
Chronic dosing depleted the pituitary’s hormone stores
2002Animal studyNot human evidence
After three weeks of treatment, the hormone content inside the pituitary cells that make growth hormone was lower than in untreated animals. This is the experimental basis for a concern FDA raises directly: that repeatedly prompting the gland to release its stores may not keep producing the same response over time.
Limitation: Rats, with the dose and route not stated in the published record. It measures what was left inside the cells rather than what circulated in the animal.
Chronic dosing followed by pituitary cell cultureView study: Chronic dosing depleted the pituitary’s hormone stores
The rat model that led to the human trials
2009Animal studyNot human evidence
The dose above is the amount used in this study. It is research information, not a recommended dose, and PepCaddie does not convert study doses into human doses.
A single dose shortened the time to a first bowel movement but changed nothing about total output, food intake or weight gain. Repeated dosing did improve all three. This is the animal result that justified taking ipamorelin into human trials for the same condition, and it is worth reading next to what those trials then found.
Limitation: A rat surgical model. It is included here as the origin of the clinical programme, and the programme it led to did not reproduce the benefit in people.
Controlled animal study of gut recovery after surgeryView study: The rat model that led to the human trials
It prompted insulin release from rat pancreas
2004Laboratory or in-vitro studyNot human evidence
Ipamorelin significantly increased insulin secretion from pancreatic tissue taken from both normal and diabetic rats. It is included because glucose handling is where the one human safety signal sits: more people on ipamorelin than on placebo had raised blood sugar at discharge in the phase 2 trial.
Limitation: Pieces of rat pancreas in a dish. There is no measurement of blood sugar in a living animal here, let alone in a person.
Laboratory study of isolated tissueView study: It prompted insulin release from rat pancreas
Black-market product found to be a different molecule
2018Laboratory or in-vitro studyNot human evidence
Analysis of black-market growth-promoting products identified three modified peptides, one of them a version of ipamorelin carrying an extra amino acid at one end. That is a different molecule from the one in the trials, sold under the same name.
Limitation: Seized samples are not a random sample of what is on sale, so this shows the modification exists rather than how common it is.
Forensic laboratory analysisView study: Black-market product found to be a different molecule
Second laboratory, same finding
2019Laboratory or in-vitro studyNot human evidence
An independent laboratory compared seized powders against reference standards and identified them not as ipamorelin and its relatives but as analogues of them, every case carrying the same extra amino acid at one end. Two laboratories in different countries found the same substitution.
Limitation: Again a seizure sample, so it establishes the practice rather than its prevalence. It does not say whether the modified molecule behaves differently.
Forensic laboratory analysis against reference standardsView study: Second laboratory, same finding
A single-volunteer detection study
2015Human observational study
One volunteer took ipamorelin nasally so that anti-doping laboratories could work out what to look for in urine. It broke down extensively, and a fragment of it remained detectable after the parent compound had cleared. This is the only other published instance of a human being given ipamorelin outside the two trials.
Limitation: One person, with no dose or duration in the published record, and no hormone measurement of any kind. It was designed to find a detection window, not to study what the compound does.
Anti-doping detection study, one volunteer per compoundView study: A single-volunteer detection study
Drugs@FDA and DailyMed: no approved or labelled ipamorelin product. U.S. Food and Drug Administration; 2026.
Official regulatory sourceChecked 2026-09-21
Read FDA's approved-drug and labelling databases at the sourceFDA briefing document, Pharmacy Compounding Advisory Committee, 29 October 2024: ipamorelin. U.S. Food and Drug Administration; 2024.
Official regulatory sourceChecked 2026-09-21
Read FDA's 2024 review of ipamorelin for compounding at the sourceFinal summary minutes, Pharmacy Compounding Advisory Committee, 29 October 2024. U.S. Food and Drug Administration; 2025.
Official regulatory sourceChecked 2026-09-21
Read The advisory committee vote: 0 in favour, 12 against at the sourceCertain bulk drug substances for use in compounding that may present significant safety risks. U.S. Food and Drug Administration; 2026.
Official regulatory sourceChecked 2026-09-21
Read FDA's compounding safety-risk listing at the sourceWarning letter: Tailor Made Compounding LLC (MARCS-CMS 594743). U.S. Food and Drug Administration; 2020.
Official regulatory sourceMARCS-CMS 594743Checked 2026-09-21
Read FDA warning letter naming ipamorelin at the sourceFDA drug enforcement reports naming ipamorelin. U.S. Food and Drug Administration, openFDA; 2026.
Official regulatory sourceChecked 2026-09-21
Read Eighteen recalls, every one for sterility at the sourceThe 2026 Prohibited List: growth hormone releasing factors. World Anti-Doping Agency; 2026.
Official regulatory sourceChecked 2026-09-21
Read WADA's 2026 Prohibited List, section S2 at the sourceBeck DE, Sweeney WB, McCarter MD; Ipamorelin 201 Study Group. Prospective, randomized, controlled, proof-of-concept study of the ghrelin mimetic ipamorelin for the management of postoperative ileus in bowel resection patients. International Journal of Colorectal Disease; 2014.
Human randomised trialPMID 25331030 · DOI 10.1007/s00384-014-2030-8 · NCT00672074Checked 2026-09-21
Read The phase 2 trial that missed its endpoint at the sourcePhase II double-blind placebo-controlled dose finding study to evaluate safety and efficacy of ipamorelin compared to placebo for recovery of gastrointestinal function following bowel resection. ClinicalTrials.gov (sponsor: Helsinn Therapeutics); 2014.
Registered clinical trialNCT01280344Checked 2026-09-21
Read The 320-patient trial that never reported at the sourceGobburu JV, Agersø H, Jusko WJ, Ynddal L. Pharmacokinetic-pharmacodynamic modeling of ipamorelin, a growth hormone releasing peptide, in human volunteers. Pharmaceutical Research; 1999.
Human randomised trialPMID 10496658 · DOI 10.1023/a:1018955126402Checked 2026-09-21
Read The only human pharmacology study, from 1999 at the sourceRaun K, Hansen BS, Johansen NL, et al.. Ipamorelin, the first selective growth hormone secretagogue. European Journal of Endocrinology; 1998.
Animal studyPMID 9849822 · DOI 10.1530/eje.0.1390552Checked 2026-09-21
Read The source of the selectivity claim at the sourceLall S, Tung LY, Ohlsson C, et al.. Growth hormone-independent stimulation of adiposity by GH secretagogues. Biochemical and Biophysical Research Communications; 2001.
Animal studyPMID 11162489 · DOI 10.1006/bbrc.2000.4065Checked 2026-09-21
Read In mice, it increased body fat at the sourceSvensson J, Lall S, Dickson SL, et al.. The GH secretagogues ipamorelin and GH-releasing peptide-6 increase bone mineral content in adult female rats. Journal of Endocrinology; 2000.
Animal studyPMID 10828840 · DOI 10.1677/joe.0.1650569Checked 2026-09-21
Read Bone gains that vanish once corrected for weight at the sourceJohansen PB, Nowak J, Skjaerbaek C, et al.. Ipamorelin, a new growth-hormone-releasing peptide, induces longitudinal bone growth in rats. Growth Hormone and IGF Research; 1999.
Animal studyPMID 10373343 · DOI 10.1054/ghir.1999.9998Checked 2026-09-21
Read Bone growth in rats, with no change in IGF-1 at the sourceJiménez-Reina L, Cañete R, de la Torre MJ, Bernal G. Influence of chronic treatment with the growth hormone secretagogue ipamorelin in young female rats: somatotroph response in vitro. Histology and Histopathology; 2002.
Animal studyPMID 12168778 · DOI 10.14670/HH-17.707Checked 2026-09-21
Read Chronic dosing depleted the pituitary’s hormone stores at the sourceVenkova K, Mann W, Nelson R, Greenwood-Van Meerveld B. Efficacy of ipamorelin, a novel ghrelin mimetic, in a rodent model of postoperative ileus. Journal of Pharmacology and Experimental Therapeutics; 2009.
Animal studyPMID 19289567 · DOI 10.1124/jpet.108.149211Checked 2026-09-21
Read The rat model that led to the human trials at the sourceAdeghate E, Ponery AS. Mechanism of ipamorelin-evoked insulin release from the pancreas of normal and diabetic rats. Neuroendocrinology Letters; 2004.
Laboratory or in-vitro studyPMID 15665799Checked 2026-09-21
Read It prompted insulin release from rat pancreas at the sourceKrug O, Thomas A, Malerød-Fjeld H, et al.. Analysis of new growth promoting black market products. Growth Hormone and IGF Research; 2018.
Laboratory or in-vitro studyPMID 29864719 · DOI 10.1016/j.ghir.2018.05.001Checked 2026-09-21
Read Black-market product found to be a different molecule at the sourceGajda PM, Holm NB, Hoej LJ, et al.. Glycine-modified growth hormone secretagogues identified in seized doping material. Drug Testing and Analysis; 2019.
Laboratory or in-vitro studyPMID 30136411 · DOI 10.1002/dta.2489Checked 2026-09-21
Read Second laboratory, same finding at the sourceSemenistaya E, Zvereva I, Thomas A, 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 Testing and Analysis; 2015.
Human observational studyPMID 25869809 · DOI 10.1002/dta.1787Checked 2026-09-21
Read A single-volunteer detection study at the source