What it is
Ipamorelin is a small synthetic peptide (a five-amino-acid chain: Aib-His-D-2-Nal-D-Phe-Lys-NH2) first described by Novo Nordisk researchers in 1998 as 'the first selective growth hormone secretagogue.' A secretagogue is a substance that prompts a gland to release something — here, it nudges the pituitary to secrete growth hormone (GH).
It was developed from an earlier peptide (GHRP-1) by stripping out part of the chain, which unexpectedly made it far more selective. Novo Nordisk explored it for medical uses but eventually shelved it, and it never reached the market.
Today ipamorelin is sold only as a 'research use only' compound. It is not a medicine, is not FDA-approved, and cannot legally be sold as a supplement or compounded for human use in the U.S.
How it works
Your stomach makes ghrelin, a hormone that signals hunger and also tells the pituitary gland to release a burst of growth hormone. Ipamorelin is a ghrelin mimic: it binds the same receptor (the growth-hormone-secretagogue receptor, GHS-R1a) and triggers a natural-feeling pulse of GH rather than flooding the body with synthetic GH. Because it works through the body's own pituitary, the release stays pulsatile and self-limiting.
Its selling point is selectivity. In the original studies, GHRP-6 and GHRP-2 also spiked cortisol and prolactin (stress and reproductive hormones), while ipamorelin raised GH without meaningfully raising cortisol, ACTH, or prolactin. It is often paired with CJC-1295, a GHRH analog: the two act on different receptors and different pathways, so combining them is theorized to produce a larger, more sustained GH pulse than either alone.
What people research it for
Raises growth hormone levels
Early human dataThe one effect with clear evidence: ipamorelin reliably produces a dose-dependent spike in plasma GH in both animals and humans in short studies.
More selective, fewer off-target hormones
Animal studiesUnlike related peptides, it raised GH without significantly bumping cortisol, ACTH, or prolactin in the foundational research — the trait it was named for.
Body-composition and bone effects
Animal studiesIn rodents it promoted body-weight gain and longitudinal bone growth, consistent with GH's known anabolic role. Whether this translates to humans is untested.
Gut-motility (postoperative recovery)
Early human dataThe main human trial tested it to speed gut recovery after abdominal surgery — a plausible use given ghrelin's GI effects — but it did not clearly beat placebo.
What the research actually shows
Human evidence is limited and, on the outcomes that were tested, unconvincing. The largest published human trial (114 patients, 2014) used IV ipamorelin to reduce postoperative ileus — sluggish gut recovery after bowel surgery. Time to first tolerated meal was 25.3 hours vs 32.6 hours for placebo, but the difference missed statistical significance (p=0.15).
After that miss, Novo Nordisk discontinued clinical development. That is the honest reason it stalled: not a scandal, but a failed primary endpoint and no path to approval. It never entered the Phase 3 trials required for FDA clearance.
So the bulk of what's 'known' about ipamorelin comes from cell and rodent studies plus short pharmacology experiments showing it raises GH. Claims about fat loss, muscle gain, recovery, sleep, and anti-aging in humans are extrapolated from GH biology, not demonstrated for ipamorelin itself.
Research handling & storage
Ipamorelin ships as a lyophilized (freeze-dried) white powder in a sealed vial. Sealed and kept cold, the powder is relatively stable; once reconstituted with bacteriostatic water it is a fragile solution that should be refrigerated and used within a few weeks. Repeated warming, light, and shaking degrade peptides.
It has a short elimination half-life of roughly two hours, so in the trials it was given by injection and dosed more than once a day. This is research context only — none of this is human-dosing guidance, and the compound is sold strictly for laboratory use.
Safety & cautions
In short studies ipamorelin was generally well tolerated, with the most commonly reported effects being flushing, headache, lightheadedness, water retention, and tingling — the usual GH-secretagogue profile. Long-term safety in humans is unknown because no long trials were ever completed, and boosting GH carries theoretical risks (blood-sugar changes, joint aches, and concerns about promoting existing tumor growth).
Ipamorelin is not FDA-approved for any use and is classified so that it cannot legally be compounded for humans in the U.S. It is banned in sport at all times by the World Anti-Doping Agency (WADA) as a growth-hormone secretagogue. 'Research use only' material is not manufactured to pharmaceutical purity standards, so identity, dose, and sterility are not guaranteed.
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Frequently asked questions
Is it FDA approved?
No. Ipamorelin has never been FDA-approved for any condition, never completed Phase 3 trials, and cannot legally be compounded or sold for human use in the U.S. It is available only as a research chemical.
Why is it combined with CJC-1295?
The two hit different targets — CJC-1295 mimics GHRH while ipamorelin mimics ghrelin — so together they're theorized to produce a bigger, longer GH pulse than either alone. This stacking is common in research/anecdotal use but hasn't been validated in approved human trials.
How is it different from other GH peptides like GHRP-6?
Selectivity. In the foundational studies GHRP-6 and GHRP-2 also raised cortisol and prolactin, whereas ipamorelin raised GH with minimal effect on those hormones — the reason it was called the 'first selective' secretagogue.
Does it actually work in humans?
It clearly raises growth hormone short-term. But its one large human trial (for gut recovery after surgery) missed its endpoint, and there are no completed human trials showing benefits for fat loss, muscle, or anti-aging.
Is it banned for athletes?
Yes. WADA prohibits ipamorelin at all times as a growth-hormone secretagogue, and it has reportedly been detected in doping cases.
Sources
- Raun et al., 'Ipamorelin, the first selective growth hormone secretagogue,' Eur J Endocrinol 1998 (PMID 9849822)
- Beck et al., proof-of-concept trial of ipamorelin for postoperative ileus, Int J Colorectal Dis 2014
- Ipamorelin — Wikipedia (developer, sequence, WADA status, half-life)
- Ishida et al., 'Growth hormone secretagogues: history, mechanism of action, and clinical development,' 2020
Last reviewed 2026-07-07. This guide is educational and research-focused — not medical advice. Ipamorelin products referenced on PeptidePub are sold by third parties as materials for laboratory research use only, not for human or animal consumption.
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