Reviewed & approved by Dr. Nova Reyes · Last checked 2026-10-15. ← Back to Evidence Library

Ipamorelin: what the evidence says

Legend: HUMAN data · ANIMAL / LAB data · UNKNOWN · UNVERIFIED: not yet confirmed against a primary source

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What is it?

Ipamorelin is a pentapeptide, a chain of 5 amino acids (Aib-His-D-2-Nal-D-Phe-Lys-NH2). It acts on the ghrelin receptor (also called the growth hormone secretagogue receptor). Novo Nordisk scientists described it in 1998 as the first "selective" growth hormone releaser. In pigs it released growth hormone without changing several other pituitary hormones (FSH, LH, prolactin, TSH). It also didn't raise ACTH or cortisol (stress hormones) beyond the levels seen with GHRH, even at very high doses. ^R1

It is a different kind of drug from CJC-1295. Ipamorelin mimics ghrelin. CJC-1295 copies GHRH, the brain's growth-hormone "on" signal. See the CJC-1295 page.

About the evidence

• Who did the studies: the early animal work came from Novo Nordisk, the developer. ^R1 The surgery trial and one rat study were linked to Helsinn, which was developing it. ^{R3, R6} We found no independent human study.
• What kind: one small human study of how the body handles the drug (a pharmacokinetic study), one published phase 2 trial (mid-size studies testing doses and early effects), one unpublished phase 2 trial, and animal studies. We found no phase 3 trial (large studies confirming benefit and safety before approval).
• Access limits: we read PubMed abstracts and registry records, not full papers. Claims seen only in summaries or vendor pages are marked UNVERIFIED.

Does it raise growth hormone?

Human Yes, briefly. In 40 healthy men given a single 15-minute IV infusion at one of five dose levels, ipamorelin caused one burst of growth hormone that peaked at about 40 minutes and then faded. Its half-life (the time it takes for half of the drug to be cleared from the body) was about 2 hours. ^R2

Animal In rats and pigs it released growth hormone about as strongly as GHRP-6. ^R1

A hormone change isn't a health benefit. No study we found tested whether ipamorelin improves muscle, fat, healing, sleep or aging in people.

Does it help the gut recover after surgery?

Human Not in the one published trial. This is the only use it was tested for in patients. - Beck 2014 (Helsinn trial NCT00672074): a phase 2, double-blind, placebo-controlled trial in 117 adults after bowel surgery (114 analyzed). Patients got IV ipamorelin or placebo in hospital for up to 7 days (study arm in the study table). The median (middle) time to tolerating a solid meal was 25.3 hours with ipamorelin vs 32.6 hours with placebo (a dummy treatment). That difference could easily be chance (p = 0.15). The authors concluded there were "no significant differences between ipamorelin and placebo" in the main or secondary measures. Bottom line: tested, no benefit shown. ^R3 - NCT01280344: a larger Helsinn phase 2 trial testing three dose levels against placebo in 320 patients after bowel surgery. It finished in May 2014. No results were posted and we found no publication. ^R4 UNVERIFIED Secondary sources say development stopped after phase 2; we found no sponsor statement. - Animal In rats after abdominal surgery, ipamorelin sped up stomach emptying and the first bowel movement. ^{R5, R6} Those animal results did not carry over to a clear benefit in the human trial.

Is it safe?

• Human Surgery trial: adverse events (problems reported after use, which may or may not have been caused by the drug) were reported by 87.5% on ipamorelin and 94.8% on placebo. The authors called it well tolerated. Use was short, in hospital, and by IV (into a vein). The abstract doesn't report dropouts because of side effects compared with placebo. ^R3
• Caution FDA: "A study published in literature identified serious adverse events including death when ipamorelin was administered intravenously for improving gastric motility." ^R7 FDA's own reviewers identified this as the Beck 2014 surgery trial, the only such study they found. At FDA's Oct 29, 2024 advisory meeting they said serious adverse events (infection, leaks at the surgical join, readmissions) and 2 deaths in the ipamorelin group occurred, and that "it is unclear whether deaths were related to ipamorelin." They also noted more low potassium, insomnia and high blood sugar at discharge on ipamorelin. ^R11 The deaths aren't in the trial abstract. UNVERIFIED Causes of death and per-group serious-event counts are reported only in the full paper, which we couldn't read from an official source.
• Caution FDA: compounded ipamorelin "may pose risk for immunogenicity" (an unwanted immune reaction) from clumping or impurities, and its unnatural amino acids make it harder to check. FDA says it lacks enough information to know whether it would cause harm by other injected routes, such as under the skin. ^R7
• Unknown Dropouts: we found no trial reporting dropouts because of side effects compared with placebo.
• Unknown Long-term use: no data. The human studies lasted one infusion ^R2 or up to 7 days in hospital ^R3. Under-the-skin use, the way it's sold, hasn't been studied in published trials.
• Caution Theoretical concern: growth hormone and IGF-1 (a growth factor) help tissue grow, which could in theory help existing tumors grow, and they can raise blood sugar. The approved GHRH drug tesamorelin carries label warnings on these points. This is a concern for the whole drug class. It has not been studied for ipamorelin. ^R9

What we don't know

• Unknown Any benefit on muscle, fat, healing, sleep or aging in people
• Unknown Safety of repeated under-the-skin use, long-term or at all
• Unknown What the unpublished 320-patient trial found
• Unknown How it interacts with CJC-1295 when mixed. Nobody has tested the combination

Is it legal?

• US: not FDA-approved. Sold online as "research use only" powder, which is not a legal medicine for people.
• FDA advisers voted against compounding it (Oct 29, 2024): FDA proposed not adding ipamorelin to the 503A bulks list, and its advisory committee voted 0 yes, 12 no, 1 abstaining, for both the free base and the acetate. ^R11 We found no final FDA rule on it.
• Compounding: FDA lists ipamorelin acetate in 503B Category 2 (substances with "significant safety risks," added Sept 29, 2023). It also appears on FDA's list of substances that were in Category 2 and whose nominations were withdrawn. (FDA page current as of Apr 22, 2026.) ^R7
• Elsewhere: we found no approval by any regulator. Caution We did not check non-US drug registries one by one.
• Athletes: WADA's 2026 list names ipamorelin under S2.2.4 (growth hormone secretagogues), banned at all times, in and out of competition. ^R8

As of Oct 15, 2026.

What's in the vial?

Unknown For "research use" or fake (counterfeit) products, the contents are unknown. Danish forensic chemists found an altered ipamorelin (with an extra amino acid) in seized doping products. ^R10 We test retail products blind under the Open Peptide Standard. See results at /tests/. A passing test covers one batch, tested on one date. It does not mean the compound itself is safe.

What do users report?

Self-report, not evidence.

Unknown TBD. We'll only list this once we can cite a public source.

Study details

^R2–R4 Human Human studies: full table

Study arms are what researchers used, not recommendations.

Study	People	Design	Study arm	Reported	Limitations	Funding / ties	Citation
Gobburu 1999	40 healthy men (8 per dose level)	Dose escalation; no placebo described	Single 15-min IV infusion, 4.21–140.45 nmol/kg	Half-life ~2 h; single GH peak at 0.67 h, then decline	Hormone levels only; one dose	Caution Not in abstract (first author SUNY Buffalo)	PMID 10496658 R2
Beck 2014 (NCT00672074)	117 enrolled, 114 analyzed; bowel resection	Phase 2, randomized, double-blind, placebo-controlled	IV 0.03 mg/kg twice daily, day 1–7 or discharge	Time to first tolerated meal 25.3 vs 32.6 h (p = 0.15, not significant); no significant difference on any efficacy measure; any adverse event 87.5% vs 94.8%; 2 deaths on ipamorelin per FDA review R11	Small; mixed conditions; dropouts not in abstract	Sponsor Helsinn (registry)	PMID 25331030 R3
NCT01280344	320 enrolled; bowel resection	Phase 2, randomized, quadruple-blind, 3 doses vs placebo	Unknown Not reported	Unknown No results posted; no publication found	Unpublished	Sponsor Helsinn (registry)	ClinicalTrials.gov R4

^{R1, R5, R6} Animal Animal and lab studies

Study	Animals / cells	Study arm	Reported	Funding / ties	Citation
Raun 1998	Rat pituitary cells; anesthetized rats; conscious pigs	Rat ED50 80 nmol/kg; pig ED50 2.3 nmol/kg	GH release similar to GHRP-6; no effect on FSH, LH, PRL, TSH; no ACTH/cortisol rise beyond GHRH	Novo Nordisk (developer)	PMID 9849822 R1
Venkova 2009	Rats after laparotomy	IV 0.01–1 mg/kg, single or repeated	Shorter time to first bowel movement (single 1 mg/kg); more fecal output, food intake, weight gain with repeated dosing	Caution Not in abstract	PMID 19289567 R5
Greenwood-Van Meerveld 2012	Rats after laparotomy	IV 0.014–0.14 µmol/kg	Faster gastric emptying (52% vs 78% of meal left)	One author at Helsinn	PMID 27186127 R6

^R7–R11 Safety, regulatory and product quality (as of Oct 15, 2026)

• ^R7 FDA, Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks (content current as of 04/22/2026): ipamorelin acetate, 503B Category 2, added Sept 29, 2023; also under "nominated but withdrawn." https://www.fda.gov/drugs/human-drug-compounding/certain-bulk-drug-substances-use-compounding-may-present-significant-safety-risks
• ^R8 WADA 2026 Prohibited List, S2.2.4: "growth hormone secretagogues (GHS) and their mimetics [e.g. … ipamorelin …]"; prohibited at all times. Checked in the official PDF text (mirror copy; wada-ama.org blocks automated download). https://www.wada-ama.org/en/resources/world-anti-doping-code-and-international-standards/prohibited-list
• ^R9 Class concern by analogy to the tesamorelin label (EGRIFTA SV). DailyMed. Not shown for ipamorelin.
• ^R11 FDA Pharmacy Compounding Advisory Committee, Oct 29, 2024, meeting transcript (https://www.fda.gov/media/185414/download): FDA review of ipamorelin; "Beck et al. study was the only available study" for postoperative ileus; "2 fatalities in the ipamorelin-treated groups, it is unclear whether deaths were related to ipamorelin"; votes on ipamorelin free base and acetate: 0 yes, 12 no, 1 abstention each.
• ^R10 Gajda 2019, Drug Test Anal: glycine-modified ipamorelin, GHRP-2, GHRP-6 and modified GRF 1-29 identified in seized products (University of Copenhagen). PMID 30136411.

Full reference list (verified on PubMed E-utilities and ClinicalTrials.gov, Oct 15, 2026)

• Raun K, et al. Eur J Endocrinol. 1998;139(5):552-61. doi:10.1530/eje.0.1390552. PMID 9849822
• Gobburu JV, et al. Pharm Res. 1999;16(9):1412-6. doi:10.1023/a:1018955126402. PMID 10496658
• Beck DE, et al. Int J Colorectal Dis. 2014;29(12):1527-34. doi:10.1007/s00384-014-2030-8. PMID 25331030
• Helsinn Therapeutics. NCT01280344 (ClinicalTrials.gov; completed 2014-05; no results posted)
• Venkova K, et al. J Pharmacol Exp Ther. 2009;329(3):1110-6. doi:10.1124/jpet.108.149211. PMID 19289567
• Greenwood-Van Meerveld B, et al. J Exp Pharmacol. 2012;4:149-55. doi:10.2147/JEP.S35396. PMID 27186127
• Gajda PM, et al. Drug Test Anal. 2019;11(2):350-354. doi:10.1002/dta.2489. PMID 30136411

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Disclaimer

This page is for education and harm reduction. It is not medical advice and not a recommendation to use ipamorelin. Its safety in humans is not established. Please talk to a clinician you trust, especially if you have or have had cancer, have diabetes or prediabetes, are pregnant, or are a tested athlete. Seek care right away for a serious reaction, and report it to FDA MedWatch (https://www.fda.gov/safety/medwatch).