Ipamorelin
Ipamorelin is a synthetic pentapeptide GH secretagogue (GHRP class) and selective agonist of the ghrelin receptor (GHS-R1a), studied for its ability to trigger pulsatile growth hormone release without significantly raising cortisol, ACTH, or prolactin; in research and enhancement circles it is frequently paired with CJC-1295, a GHRH-receptor analog, for a proposed synergistic GH pulse.
Ipamorelin reconstitution calculator
Open full calculator →Typical dosing
| Goal | Range | Route | Frequency |
|---|---|---|---|
| Postoperative ileus (Phase 2 trial, Beck et al. 2014 — the only substantial human dosing data) | 0.03 mg/kg | IV infusion | 2x daily, postoperative day 1-7 or until discharge; well tolerated but did not beat placebo |
| Community protocol for GH-axis stimulation (no trial basis) | 100-300 mcg | SubQ | 1-3x daily |
| Community protocol — paired with CJC-1295 (no DAC / mod GRF 1-29) | ~100 mcg of each, co-administered | SubQ | 1-3x daily; this combination has never been tested in a controlled human trial |
| Community timing convention (mechanistic rationale, not trial-validated) | Same per-dose amounts | SubQ | Typically dosed fasted and/or at bedtime, on the theory that food intake blunts the GH pulse |
| FDA-approved dosing | None exists | n/a | Not FDA-approved for any indication — there is no label and no established human dose for GH-axis use |
Ranges compiled from research literature — not a prescription.
How it works
Ipamorelin is a synthetic pentapeptide first characterized by Raun et al. (1998) at Novo Nordisk, who described it as "the first selective growth hormone secretagogue." It acts as an agonist at the growth hormone secretagogue receptor (GHS-R1a) — the same receptor endogenous ghrelin binds — stimulating pituitary somatotrophs to release growth hormone in a pulsatile pattern that mimics natural GH secretion rhythms.
What distinguishes ipamorelin from earlier GHRP-class secretagogues (GHRP-6, GHRP-2, hexarelin) is its selectivity. In the original Raun et al. swine studies, ipamorelin raised GH robustly but did not produce ACTH or cortisol elevations significantly different from GHRH stimulation alone, and left FSH, LH, prolactin, and TSH unaffected — a selectivity margin the authors reported held even at high multiples of the ED50 for GH release. This is the main mechanistic claim distinguishing it from older, less selective GHRPs.
Ipamorelin is commonly paired in research and off-label use with CJC-1295, a GHRH-receptor agonist. The rationale is dual-receptor stimulation: CJC-1295 acts on the GHRH receptor while ipamorelin acts on GHS-R1a, and activating both pathways together has been shown with other GHRH+GHS combinations to produce a larger GH pulse than either agonist alone. However, direct clinical trial data on the ipamorelin+CJC-1295 combination specifically (dosing, PK interaction, long-term outcomes) is not established in the peer-reviewed literature — the synergy rationale is extrapolated from receptor pharmacology and older combination studies, not from dedicated trials of this pairing.
The evidence base for ipamorelin overall remains preclinical-heavy: most mechanistic and selectivity data comes from rodent and swine studies. The largest human dataset comes from Phase II trials testing IV ipamorelin for postoperative ileus after bowel surgery — a GI motility indication unrelated to bodybuilding, anti-aging, or fat-loss uses it is marketed for online. There is no published long-term human safety or efficacy data for GH-axis stimulation via subcutaneous ipamorelin in healthy adults, and it is not FDA-approved for any indication.
Side effects & safety
- Injection-site reactions: redness, itching, swelling, or bruising at the SubQ site.
- Increased hunger/appetite, a known ghrelin-receptor-mediated effect.
- Water/fluid retention and mild edema, reported with GH secretagogues generally.
- Theoretical concerns from sustained IGF-1 elevation (insulin sensitivity changes, unknown long-term tissue effects) that are not established by controlled human trials.
- No long-term human safety or efficacy data exists for GH-axis stimulation use; the only substantial human trials studied short-course IV dosing for postoperative ileus, not chronic SubQ self-administration.
- Not FDA-approved for any use, classified as WADA Prohibited List S2 at all times, and unregulated research-chemical sources carry unverified purity — consult a licensed clinician before considering use.
Research
Primary sources — PubMed.
- Raun K, et al. Ipamorelin, the first selective growth hormone secretagogue. Eur J Endocrinol. 1998. https://pubmed.ncbi.nlm.nih.gov/9849822/
- Johansen PB, et al. Ipamorelin, a new growth-hormone-releasing peptide, induces longitudinal bone growth in rats. Growth Horm IGF Res. 1999. https://pubmed.ncbi.nlm.nih.gov/9733495/
- Andersen NB, et al. The effect of ipamorelin on GH secretion. https://pubmed.ncbi.nlm.nih.gov/9879640/
- Gobburu JV, et al. Pharmacokinetic-pharmacodynamic modeling of ipamorelin. https://pubmed.ncbi.nlm.nih.gov/10373343/
- Beck DE, et al. Ipamorelin for postoperative ileus — Phase II. https://link.springer.com/article/10.1007/s00384-014-2030-8
- World Anti-Doping Agency. The Prohibited List — S2. https://www.wada-ama.org/en/prohibited-list