Ipamorelin is sold for daily subcutaneous injection, usually beside CJC-1295, and its side-effect lists on seller pages are short and confident. The record behind them is narrow. Every human trial gave it intravenously, to people recovering from bowel surgery or to healthy men for a single infusion. None measured what happens with months of subcutaneous use.
What it is and where it came from is on Peptide Lexicon's ipamorelin entry; what the labelled and trial doses are is on our CJC-1295 and ipamorelin dosage page. This page counts the harms.
The surgical trials
Helsinn Therapeutics tested ipamorelin as a treatment for post-operative ileus, the gut slowdown after abdominal surgery. Two phase 2 trials are registered:
| Trial | Patients | Regimen | What is public |
|---|---|---|---|
| NCT00672074 (2008–2009) | 117 enrolled, 114 evaluable | 0.03 mg/kg IV twice daily, up to 7 days | Published: Beck et al. 2014 |
| NCT01280344 (2011–2014) | 320 enrolled | IV vs saline | No posted results; no paper found |
The published trial's safety finding is a total: any treatment-emergent adverse event in 87.5% on ipamorelin and 94.8% on placebo. Its efficacy endpoint missed — median time to a tolerated solid meal was 25.3 hours against 32.6 (p = 0.15). The authors called the drug "well tolerated", and in that setting that is a fair reading. It is also a reading about patients with fresh abdominal wounds, monitored in hospital for a week. Nausea, pain and fever are what bowel surgery produces; a trial in that population cannot isolate the milder effects a healthy user would notice.
The larger trial, three times the size, never reported. ClinicalTrials.gov listed no results for it when we read it on 4 October 2026, and PubMed returned no paper. Its adverse-event table — the biggest ipamorelin safety dataset ever collected — is not public.
The healthy-volunteer study
The one study in healthy people (Gobburu et al. 1999) infused ipamorelin over 15 minutes at five dose levels, eight men per level. It reported pharmacokinetics: a terminal half-life of 2 hours and a single growth-hormone pulse peaking at 0.67 hours at every dose. It was not designed as a safety study and the abstract carries no adverse-event figures. PubMed lists 50 records with ipamorelin in the title or abstract; only these two are tagged as clinical trials.
The "no cortisol" claim
The most repeated safety point about ipamorelin — that unlike older secretagogues it does not raise cortisol — comes from the developer's own 1998 pharmacology paper (Raun et al.). In swine, ipamorelin did not raise ACTH or cortisol even at doses more than 200-fold above its growth-hormone ED50, while GHRP-6 and GHRP-2 did. That is a real and specific finding, and it is an animal one. No published human study has measured cortisol, prolactin or glucose across repeated subcutaneous dosing. How the two older peptides compare is on our GHRP-2 vs GHRP-6 page.
What FDA has on file
openFDA's adverse-event endpoint returned 11 reports naming ipamorelin on 4 October 2026. We opened each one:
| Role coded for ipamorelin | Reports | Reaction terms |
|---|---|---|
| Suspect drug | 3 | Arthralgia (2020); drug hypersensitivity with preparation errors (2026); myocardial infarction, acute kidney injury, low potassium, dyspnoea, dysphagia (2026, a CJC-1295/ipamorelin product) |
| Concomitant only | 8 | Including injection-site abscess, rash, chills, night sweats, raised blood pressure, injection-site pain |
Four of the concomitant reports, all from 2022, carry the coded term "recalled product administered", alongside other compounded drugs. Eleven reports cannot produce a rate, and a report records that someone noticed something, not that the drug caused it. Why the numbers are this small for every research compound is on our peptide side-effects overview.
FDA's 2023 risk entry
On 29 September 2023 FDA listed ipamorelin acetate, nominated for the 503B outsourcing list, among bulk substances that may present significant safety risks. Its stated reasons: possible immunogenicity from aggregation or peptide-related impurities; unnatural amino acids in the molecule that make characterisation harder; and "a study published in literature" that identified serious adverse events including death when ipamorelin was given intravenously for gastric motility. FDA added that it had no safety information for other injectable routes.
FDA does not name the study. The only published intravenous trial in that indication is Beck 2014, whose abstract reports totals, not individual serious events; in a bowel-surgery population, deaths can occur in either arm. A reader cannot check the claim from the public record, and we have not seen the full paper's serious-event table. The full list is indexed on our FDA category 2 page.
What the receptor class shows
Ipamorelin acts on the ghrelin (GHS) receptor. One drug acting there has a current FDA label: Macrilen (macimorelin), an oral diagnostic given once to test for adult growth-hormone deficiency. Its label warns of QT prolongation of about 11 ms and lists, in 154 people:
| Reaction | Share |
|---|---|
| Dysgeusia | 4.5% |
| Dizziness | 3.9% |
| Headache | 3.9% |
| Fatigue | 3.9% |
| Nausea | 3.2% |
| Hunger | 3.2% |
Macimorelin is a different molecule, taken by mouth, once. The table shows what this receptor can do in people who were measured. It is not evidence about ipamorelin.
What nobody has measured
- Any adverse effect of subcutaneous ipamorelin, at any dose, for any duration.
- Effects of repeated dosing over weeks or months: glucose, insulin, water retention, IGF-1 over time.
- Antibodies to ipamorelin, the risk FDA named.
- Ipamorelin combined with CJC-1295, the way most of it is sold; the trial record for that pairing is on our CJC-1295 side effects page.
- What is actually in a research-market vial, which a certificate of analysis only partly answers.
Anyone with symptoms after using ipamorelin should tell a doctor what the product was, where it came from and how it was used.
Sources and dates
- Beck DE et al. Int J Colorectal Dis 2014;29:1527–34, PMID 25331030 (abstract read 2026-10-04).
- ClinicalTrials.gov v2 API, intervention "ipamorelin": NCT00672074, NCT01280344 (read 2026-10-04).
- Gobburu JV et al. Pharm Res 1999;16:1412–6, PMID 10496658; Raun K et al. Eur J Endocrinol 1998;139:552–61, PMID 9849822 (abstracts read 2026-10-04).
- PubMed E-utilities: ipamorelin[tiab] 50 records, 2 tagged clinical trial (2026-10-04).
- openFDA drug adverse-event endpoint, medicinal product "ipamorelin", all 11 reports opened (2026-10-04).
- FDA, Certain bulk drug substances for use in compounding that may present significant safety risks, ipamorelin acetate entry; content current as of 2026-04-22 (read 2026-10-04).
- MACRILEN (macimorelin) prescribing information, NDA 205598, via openFDA, effective 2021-01-30 (read 2026-10-04).
Corrections go to the contact page.