Quick Facts
Plain-English Summary
Ipamorelin is a synthetic pentapeptide growth hormone releasing peptide (GHRP) and selective agonist of the ghrelin receptor (GHS-R1a). Developed by Novo Nordisk in the 1990s, it was studied clinically under the designation NNC 26-0161 and entered phase IIb trials for postoperative ileus via Helsinn Healthcare. Its primary distinction within the GHRP class is selectivity: unlike GHRP-2 and GHRP-6, Ipamorelin stimulates GH release without significantly elevating cortisol, prolactin, or ACTH. This selectivity makes it the preferred GHRP in research and clinical practice contexts, and it is most commonly combined with a GHRH analogue (CJC-1295 or Sermorelin) to amplify GH pulses through complementary receptor pathways.
No completed RCTs have examined Ipamorelin specifically for body composition, anti-ageing, or performance endpoints in healthy adults. Community protocols are not supported by a controlled human evidence base for these goals.
Mechanism of Action
Proposed mechanisms below are derived from in vitro and rodent studies only. No mechanistic pathway has been validated in a controlled human study.
All mechanistic data is derived from in vitro or rodent studies. Applicability of these pathways in humans is not established.
Animal Data
| Model | Finding | ICPS Status |
|---|---|---|
| Rat selectivity study | Raun et al. (1998) demonstrated robust GH release without cortisol or prolactin elevation at doses that stimulate ACTH with other GHRPs. Foundational selectivity data. Raun et al. 1998 ↗ | Preclinical |
| Rat longitudinal bone growth | Johansen et al. (1999) confirmed dose-dependent IGF-1 increases and longitudinal bone growth effects consistent with GH axis stimulation. Johansen et al. 1999 ↗ | Preclinical |
| Multi-species GH secretion | Equine and porcine studies support the selectivity findings across species, with GH stimulation absent of meaningful ACTH co-stimulation across all tested species. | Preclinical |
| Rat GI motility | Gastrointestinal motility effects documented in rat models, providing mechanistic support for the postoperative ileus indication pursued in clinical development by Helsinn Healthcare. | Preclinical |
No finding from this section has been replicated in a controlled human trial. Animal-to-human translation for peptides is uncertain and cannot be assumed.
Human Trials
| Trial | Population | Status | ICPS Status |
|---|---|---|---|
| Phase IIb — Postoperative Ileus | Surgical patients; bowel motility recovery endpoint; conducted by Helsinn Healthcare | — | Incomplete |
| PD studies — healthy volunteers | Healthy adults; confirmed GH pulse induction and IGF-1 elevation at pharmacodynamic doses | — | Limited |
| Body composition / anti-ageing / performance | — | — | No Data |
Ipamorelin has no FDA, EMA, or Health Canada–approved indications and no published Phase III trial data for any condition as of 2026.
Safety & Side Effects
Ipamorelin has the most favourable safety profile of the GHRP class. Unlike GHRP-2 and GHRP-6, it does not cause significant cortisol elevation, substantial appetite stimulation, or prolactin increase. The Helsinn clinical program provides genuine clinical safety data not available for many research peptides.
GH-elevating compounds carry standard precautions: potential for IGF-1 elevation, theoretical risk in malignancy or pre-malignant states, and unknown long-term effects in healthy adults. Periodic monitoring of IGF-1 and metabolic markers is recommended for extended use.
- Mild transient flushing post-injection
- Tingling or warmth sensation at injection site
- Mild appetite increase (significantly less than GHRP-6)
- Headache in initial days of use
- No pharmacovigilance database exists for Ipamorelin outside of clinical trials
- Active or suspected malignancy
- Pregnancy or breastfeeding
- Diabetic retinopathy or significant insulin resistance
- Hormone-sensitive conditions
- Children and adolescents
Ipamorelin is not approved by the FDA, EMA, or Health Canada for any medical indication. It is classified as a research compound and is not legal for human therapeutic use in most jurisdictions. Procurement and use outside of registered clinical trials carries regulatory and unknown health risks.
References
Research disclaimer. CompoundProfile publishes summaries of available scientific literature for educational purposes only. This page does not constitute medical advice and should not be interpreted as an endorsement of Ipamorelin for any therapeutic use. Consult a licensed healthcare professional before considering any research compound. All evidence gradings reflect the state of published literature as of August 2026 and are assessed independently by ICPS.
Community Commentary
Selected discussion from r/Peptides · Curated for signal, not volume
Switched from GHRP-6 to Ipamorelin 18 months ago. The difference in sides is stark — no hunger spikes, no cortisol issues, same or better GH response. Should be the default recommendation for anyone starting GHRPs.
The selectivity data in Raun 1998 predicted exactly this. Took the biohacking community a decade to catch up to what the pharmacology already showed.
Pre-sleep Ipamorelin + Mod GRF has been part of my protocol for 2 years. Sleep quality improved measurably (tracked with Oura). IGF-1 up 40 points from baseline. Recovery noticeably faster. No adverse events.
The Helsinn clinical program for postoperative ileus is underappreciated context here. This compound went through proper IND/clinical development. It's not just a research chemical — it's a failed drug candidate with actual clinical safety data.
Good point. The clinical safety data is genuinely reassuring relative to compounds that have never been near a trial.
For anyone choosing between GHRPs: GHRP-6 has the most GH bang but causes hunger and cortisol issues. GHRP-2 is middle ground. Ipamorelin is cleanest but modest GH stimulation as monotherapy. Stack it with a GHRH analogue.