Ipamorelin Side Effects and Benefits: Research Data
What ipamorelin does at the ghrelin receptor, what animal and human studies reported, why its surgical trial failed, and what FDA says about its safety.
Update History ▾
Research-use-only framing applied throughout in line with Remy editorial standards.
Ipamorelin side effects in people are known from only two small kinds of study: a pharmacology study in healthy men and trials in patients recovering from bowel surgery. Its reputation as a “clean” growth hormone secretagogue comes from animal data. In swine it released growth hormone without raising cortisol or ACTH,[1] and in a phase 2 surgical trial adverse events were no more frequent than with placebo, but the drug showed no benefit.[2] FDA nonetheless lists ipamorelin as a bulk substance that may present significant safety risks.[3]
The benefits claimed for ipamorelin, such as fat loss, muscle gain, deeper sleep or better recovery, have not been tested in any human trial. It is not an approved medicine, it is prohibited in sport, and Remy Research supplies it for in-vitro laboratory research only.
What Is Ipamorelin?
Ipamorelin is a synthetic pentapeptide, Aib-His-D-2-Nal-D-Phe-Lys-NH2, developed by Novo Nordisk in the 1990s from a series of growth hormone releasing peptides (GHRPs). Its developers called it the first selective growth hormone secretagogue.[1] It has a molecular formula of C38H49N9O5 and a molecular weight of 711.9.[4] It is a research compound among the growth hormone peptides, not a hormone and not growth hormone itself: it works by stimulating the body’s own growth hormone secretion from the pituitary.
How Ipamorelin Works: The Ghrelin Receptor Pathway
Ipamorelin acts on the growth hormone secretagogue receptor (GHS-R), a receptor in the pituitary and hypothalamus first described in 1996.[5] Experiments with receptor blockers showed that ipamorelin releases growth hormone through this GHRP-type receptor, not through the GHRH receptor that sermorelin and tesamorelin use.[1] The natural ligand of the same receptor is ghrelin, a stomach hormone that also stimulates appetite through the hypothalamus.[6]
What set ipamorelin apart from older growth hormone releasing peptides was its selectivity. In conscious swine, the related peptides GHRP-2 and GHRP-6 raised ACTH and cortisol, while ipamorelin did not raise either above the levels seen with a GHRH stimulus, even at more than 200 times the amount needed for half its growth hormone effect. None of the peptides affected FSH, LH, prolactin or TSH, so ipamorelin left the other hormonal axes of the endocrine system unchanged in that test.[1] This is the basis for the “no cortisol, no prolactin” claims, and it is an animal finding.
Ipamorelin Benefits: What Studies Reported
| Claimed benefit | What was reported | Evidence type |
|---|---|---|
| Growth hormone release | GH release in pituitary cells, rats and swine, similar to GHRP-6 | Cell and animal |
| No cortisol rise | No ACTH or cortisol increase beyond GHRH levels | Animal (swine) |
| GH pulse in people | A single GH pulse in healthy men | Human pharmacology |
| Bone growth | Faster longitudinal bone growth and weight gain | Animal (rats) |
| Gut motility | Faster first bowel movement after surgery | Animal (rats) |
| Surgical recovery | No significant benefit over placebo | Human phase 2 trial |
| Fat loss, sleep, muscle | Not measured in any ipamorelin study | None |
Growth Hormone Release in Humans
The only published human pharmacology study studied ipamorelin at five escalating levels in healthy men, eight per level. Each level produced a single episode of growth hormone release peaking at about 0.67 hours and falling back to negligible levels; ipamorelin had a terminal half life of about 2 hours, and the growth hormone response varied more between people than drug levels did.[7]
Bone Growth and Body Weight in Rats
In adult female rats, 15 days of ipamorelin increased longitudinal bone growth and body weight gain in a dose-related way, without changing total IGF-1 or markers of bone turnover. The pituitary’s growth hormone response to a later ipamorelin challenge was slightly reduced.[8]
Gut Motility After Surgery
Because ghrelin speeds the gut, ipamorelin was developed for the treatment of postoperative ileus, the slow return of bowel function after abdominal surgery. In rats it shortened the time to the first bowel movement, and repeated exposure increased food intake and body weight gain; the authors suggested it might ease ileus symptoms.[9] In people it did not work: the human trial is described below.
Human Evidence: Two Phase 2 Trials
Helsinn registered two Phase 2 trials of ipamorelin for recovery of gut function after surgery.[10] The published one enrolled 117 adults having small or large bowel resection; time to the first tolerated solid meal was 25.3 hours with ipamorelin and 32.6 hours with placebo, a difference that was not statistically significant, and no secondary efficacy measure differed either.[2] The larger trial, with 320 participants, was completed in 2014 and has no posted results.[10] No trial has studied ipamorelin for body composition, fat loss, muscle, sleep quality or aging, and development did not reach Phase 3.
Ipamorelin Side Effects and Safety Profile
- Surgical trial. Treatment-emergent adverse events occurred in 87.5% of patients on ipamorelin and 94.8% on placebo, and the authors judged it well tolerated; the population had just had bowel surgery.[2]
- Serious events cited by FDA. FDA states that a published study identified serious adverse events including death when ipamorelin was given intravenously for gastric motility, and links its Category 2 entry to that trial.[3] The trial’s abstract does not mention deaths and describes ipamorelin as well tolerated, so the two accounts should be read together.[2]
- Immunogenicity. Among FDA’s safety concerns, it says compounded ipamorelin may pose a risk of immune reactions for certain routes because of aggregation or peptide-related impurities, and that its unnatural amino acids complicate characterisation.[3]
- Unknown risks by other routes. FDA has not identified safety information for certain other injectable routes and says it cannot tell whether ipamorelin would cause harm by them.[3]
- Appetite and weight. Ghrelin is an appetite hormone, and repeated ipamorelin raised food intake and body weight in rats; this has not been measured in people.[6][9]
Joint pain, water retention, fatigue and blood sugar changes are not reported as ipamorelin findings in the published human studies above. Long term use has never been studied.
Is Ipamorelin FDA Approved?
- FDA approval. No. Ipamorelin is not an approved drug; its registered trials stopped at Phase 2.[10]
- Compounding. FDA added ipamorelin acetate to 503B Category 2 on September 29, 2023, and lists its 503A nomination as withdrawn.[3]
- Sport. WADA’s 2027 List names ipamorelin among growth hormone secretagogues under S2.2.4, prohibited at all times.[11]
- UAE. Remy Research supplies ipamorelin for in-vitro laboratory research only. It is not for human consumption or veterinary use.
Ipamorelin vs Sermorelin and CJC-1295
Sermorelin is GHRH(1-29), the shortest fragment of growth hormone releasing hormone with its full activity, and it acts on the GHRH receptor; it was once an approved pediatric medicine.[12] Ipamorelin acts on the ghrelin receptor instead, so the two use different pathways to the same pituitary cells. Both are named under WADA S2.2.4.[11] For the full GHRH comparison, see tesamorelin vs sermorelin.
Ipamorelin is often paired with CJC-1295, a long-acting GHRH analog, so that the GHRH-receptor and ghrelin-receptor pathways are stimulated together. The idea comes from physiology: natural ghrelin and GHRH given in combination produced a synergistic growth hormone rise in healthy men.[13] CJC-1295 with DAC, on its own, raised growth hormone and IGF-1 for days in healthy adults, with a half life of 5.8 to 8.1 days.[14] FDA, however, cites serious adverse events with CJC-1295, including increased heart rate.[3] The ipamorelin and CJC-1295 combination itself has not been tested in a trial; see CJC-1295 + ipamorelin side effects and benefits.
What Ipamorelin Research Does Not Yet Show
- Selectivity in humans. The cortisol and prolactin findings come from swine.[1]
- Any clinical benefit. Its one published efficacy trial was negative.[2]
- Effects of repeated exposure in people. The human pharmacology data are single infusions.[7]
- The second trial’s results. The 320-person trial has never reported.[10]
- Body composition and sleep. No ipamorelin study in people has measured body composition, fat, muscle or sleep.[10][7]
Ipamorelin for Laboratory Research
Remy Research supplies ipamorelin, one of its growth hormone research peptides, for in-vitro research as the Genovare ipamorelin 25mg AQ pen, and in combination products as the CJC-1295 (no DAC) + ipamorelin 10mg vial, the Genovare CJC-1295 + ipamorelin 50mg AQ pen and the Genovare Super Geno I 36mg AQ pen. Each product page carries its batch testing details. For the original mechanism review, read the ipamorelin research profile.
Our Research Standards
This article prioritizes primary literature, trial registries and regulator records, and keeps cell, animal and human evidence apart. Where no human data exist, we say so directly. No therapeutic, dosing or administration guidance is given. Read our editorial policy →
Ipamorelin Side Effects and Benefits FAQ
What are the side effects of ipamorelin?
What is ipamorelin?
A synthetic five-amino-acid growth hormone secretagogue that acts on the ghrelin receptor. Its developers called it the first selective growth hormone secretagogue.[1]
What are the benefits of ipamorelin?
Is ipamorelin FDA approved?
No. FDA lists ipamorelin acetate in 503B Category 2 as a bulk substance that may present significant safety risks.[3]
Is ipamorelin safe?
Does ipamorelin raise cortisol?
Not in swine, where it did not raise ACTH or cortisol beyond GHRH levels. The published human pharmacology study measured growth hormone, not cortisol.[1]
Does ipamorelin reduce belly fat?
There is no evidence that it does. No ipamorelin study has measured body fat; in rats it increased body weight gain.[8]
What is the difference between ipamorelin and sermorelin?
Is ipamorelin banned by WADA?
Yes. It is named under S2.2.4 of the 2027 Prohibited List and is prohibited at all times.[11]
Sources
- Raun K, Hansen BS, Johansen NL, et al. Ipamorelin, the first selective growth hormone secretagogue. Eur J Endocrinol. 1998;139(5):552-561. doi: 10.1530/eje.0.1390552 · PMID: 9849822 ↩
- Beck 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. Int J Colorectal Dis. 2014;29(12):1527-1534. doi: 10.1007/s00384-014-2030-8 · PMID: 25331030 ↩
- U.S. Food and Drug Administration. Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks (Category 2, including “Bulk drug substances nominated but withdrawn”). Content current as of April 22, 2026. fda.gov ↩
- National Center for Biotechnology Information. PubChem Compound Summary for CID 9831659, Ipamorelin (C38H49N9O5; molecular weight 711.9). pubchem.ncbi.nlm.nih.gov/compound/9831659 ↩
- Howard AD, Feighner SD, Cully DF, et al. A receptor in pituitary and hypothalamus that functions in growth hormone release. Science. 1996;273(5277):974-977. doi: 10.1126/science.273.5277.974 · PMID: 8688086 ↩
- Kojima M, Kangawa K. Ghrelin: structure and function. Physiol Rev. 2005;85(2):495-522. doi: 10.1152/physrev.00012.2004 · PMID: 15788704 ↩
- Gobburu JV, Agersø H, Jusko WJ, Ynddal L. Pharmacokinetic-pharmacodynamic modeling of ipamorelin, a growth hormone releasing peptide, in human volunteers. Pharm Res. 1999;16(9):1412-1416. doi: 10.1023/a:1018955126402 · PMID: 10496658 ↩
- Johansen PB, Nowak J, Skjaerbaek C, et al. Ipamorelin, a new growth-hormone-releasing peptide, induces longitudinal bone growth in rats. Growth Horm IGF Res. 1999;9(2):106-113. doi: 10.1054/ghir.1999.9998 · PMID: 10373343 ↩
- Venkova K, Mann W, Nelson R, Greenwood-Van Meerveld B. Efficacy of ipamorelin, a novel ghrelin mimetic, in a rodent model of postoperative ileus. J Pharmacol Exp Ther. 2009;329(3):1110-1116. doi: 10.1124/jpet.108.149211 · PMID: 19289567 ↩
- ClinicalTrials.gov API v2. Ipamorelin studies: NCT00672074 (Phase 2, Helsinn, 117 enrolled, completed) and NCT01280344 (Phase 2, Helsinn, 320 enrolled, completed 2014; no results posted). Queried October 27, 2026. clinicaltrials.gov ↩
- World Anti-Doping Agency. 2027 Prohibited List (in force January 1, 2027), S2.2.4 Growth hormone releasing factors: growth hormone secretagogues (GHS) and their mimetics, e.g. ipamorelin; GHRH and its analogues, e.g. sermorelin; prohibited at all times. wada-ama.org ↩
- Prakash A, Goa KL. Sermorelin: a review of its use in the diagnosis and treatment of children with idiopathic growth hormone deficiency. BioDrugs. 1999;12(2):139-157. doi: 10.2165/00063030-199912020-00007 · PMID: 18031173 ↩
- Arvat E, Maccario M, Di Vito L, et al. Endocrine activities of ghrelin, a natural growth hormone secretagogue (GHS), in humans: comparison and interactions with hexarelin, a nonnatural peptidyl GHS, and GH-releasing hormone. J Clin Endocrinol Metab. 2001;86(3):1169-1174. doi: 10.1210/jcem.86.3.7314 · PMID: 11238504 ↩
- Teichman SL, Neale A, Lawrence B, Gagnon C, Castaigne JP, Frohman LA. Prolonged stimulation of growth hormone (GH) and insulin-like growth factor I secretion by CJC-1295, a long-acting analog of GH-releasing hormone, in healthy adults. J Clin Endocrinol Metab. 2006;91(3):799-805. doi: 10.1210/jc.2005-1536 · PMID: 16352683 ↩
For catalog details, see the Genovare ipamorelin 25mg AQ pen, the CJC-1295 (no DAC) + ipamorelin 10mg vial, the Genovare CJC-1295 + ipamorelin 50mg AQ pen and the Genovare Super Geno I 36mg AQ pen. For editorial standards, continue to the editorial policy.