Underground Biohacking
Growth hormone

Ipamorelin

Chris Hallewell, founder of Underground Biohacking

By , Founder, Underground Biohacking

Last reviewed

Research use only. Not FDA-approved. Banned by WADA (S2.2 category).

Ipamorelin is a lab made peptide that tells your pituitary gland to release a pulse of growth hormone. It does that in people: a study in healthy men measured a clear growth hormone burst. But the one proper efficacy trial, in bowel surgery patients, failed. Ipamorelin did no better than placebo. Every claim about muscle, fat loss, bone or recovery rests on rats, mice, pigs or cells. It is not an approved medicine.

What is Ipamorelin?

Ipamorelin is a pentapeptide, meaning it is built from five amino acids joined in a chain. It came out of a drug programme at Novo Nordisk in the 1990s. It belongs to a class called growth hormone secretagogues (drugs that make your own pituitary release growth hormone, rather than injecting the hormone itself). It works at the ghrelin receptor, the same switch your hunger hormone uses. The structure matters in two ways. Chemists found it by stripping a central pair of amino acids out of an older peptide, GHRP-1. It also carries unnatural D form amino acids, which your body never builds itself. Those odd building blocks are part of why regulators call the peptide hard to characterise and to check for impurities. Its inventors named it "the first selective growth hormone secretagogue". The selective part refers to one finding in pigs. It raised growth hormone without raising cortisol, the stress hormone that older peptides pushed up. That is a real published result, and it is the reason ipamorelin is talked about at all.

What is Ipamorelin used for?

  • In healthy men, an infusion of ipamorelin produced a single burst of growth hormone that peaked within the hour and then faded away.[1]Human study
  • In a randomised trial in people recovering from bowel surgery, ipamorelin did not beat placebo on the main measure or the backup measures.[2]Human study
  • In pigs, ipamorelin raised growth hormone without raising ACTH or cortisol, the stress hormones that older peptides in its class did push up.[3]Animal or lab study only
  • In that same pig work, none of the tested secretagogues changed prolactin, TSH, or the reproductive hormones LH and FSH.[3]Animal or lab study only
  • In adult rats given a steroid that wastes muscle and bone, adding ipamorelin restored calf muscle force and raised the bone building rate fourfold.[4]Animal or lab study only
  • In adult female rats, ipamorelin raised total bone mineral content, but that came from bigger bones rather than denser ones.[5]Animal or lab study only
  • In rats whose stomachs had stalled after abdominal surgery, ipamorelin sped up stomach emptying by making the stomach muscle contract again.[6]Animal or lab study only
Ipamorelin dosage chart
Typical dose200-300mcg per injection, 2-3 times per day
Cycle length8-12 weeks on, 4 weeks off
FormInjectable (subcutaneous)

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How does Ipamorelin work?

Ipamorelin is a pentapeptide, a chain of just five amino acids. It works on the ghrelin receptor in the pituitary gland, the same switch your hunger hormone ghrelin uses. Flipping that switch triggers a pulse of growth hormone. What made it notable is what it leaves alone. In conscious pigs, ipamorelin raised growth hormone without raising ACTH or cortisol, your main stress hormones. Two older peptides in the same family, GHRP-2 and GHRP-6, did raise both. Note where that came from. The selectivity was measured in pigs, not in people, so treat it as a promising lead rather than a settled human fact.

How much Ipamorelin should you take?

200-300mcg per injection, 2-3 times per day

How long should you run Ipamorelin?

8-12 weeks on, 4 weeks off

How is Ipamorelin supplied?

Injectable (subcutaneous)

What are the side effects of Ipamorelin?

EffectHow seriousWhat to watch
In the one published human trial, side effects of some kind hit almost everyone. The rate was slightly lower on ipamorelin than on placebo, so the trial did not pin anything specific on the drug.[2]Very common, but no worse than placebo in that trialAnything new after starting, and tell any doctor treating you that you are taking it
A 2026 review covers growth hormone peptides that people buy and inject on their own. It lists hormone and blood sugar problems, fluid retention, aching muscles and joints, and injection site reactions.[7]Varies, some are seriousSwelling, joint and muscle ache, blood sugar, and the skin where you inject
The same review grades this family of peptides on a scale. It runs from real trial data down to no human studies at all. The review says the claimed benefits remain uncertain.[7]UnknownTreat any confident claim about long term safety as unproven
In mice, secretagogues including ipamorelin increased body fat and food intake. That happened by a route which did not need growth hormone.[8]Unknown in peopleAppetite and weight
In pancreas tissue taken from rats, ipamorelin pushed out more insulin, in healthy and diabetic animals alike. Nobody has checked what that does to blood sugar in people.[9]Unknown in peopleBlood sugar, especially if you are diabetic or take insulin

Is Ipamorelin legal in 2026?

Checked on 6 August 2026. Ipamorelin is not an approved medicine. FDA keeps a list of bulk drug substances that may present significant safety risks. Ipamorelin acetate sits in category 2 on that list, for section 503B outsourcing facilities. It was added on 29 September 2023, and the page was current as of 22 April 2026. FDA says compounded ipamorelin may carry an immune reaction risk. It says the unnatural amino acids make the peptide hard to characterise. It also cites published research reporting serious adverse events, including death, when ipamorelin was given into a vein for stomach motility. Category 2 means FDA would consider enforcement action against a compounder who uses it. Nothing in that position has changed.

Status checked against the primary source.

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Frequently Asked Questions

Does ipamorelin actually raise growth hormone in people?
Yes. That part is settled. A study in healthy male volunteers measured growth hormone in the blood after ipamorelin was infused. It produced one burst that peaked inside the first hour and then dropped back towards nothing. That is the strongest human finding on this peptide. Note what it does not show. Raising growth hormone for an hour is not the same as changing your muscle, your fat or your health.
Did ipamorelin ever fail a clinical trial?
Yes, and this is the part most write ups leave out. It was tested in a randomised, placebo controlled phase 2 trial in patients recovering from bowel surgery. The target was postoperative ileus, where the gut stops moving after an operation. Ipamorelin did not beat placebo on the main measure or the secondary ones. The programme did not go on to succeed. That is the only efficacy trial in people that has been published.
Is ipamorelin really selective, with no cortisol or prolactin spike?
The claim traces back to one 1998 paper, and it was measured in pigs, not people. In that work ipamorelin raised growth hormone but left ACTH and cortisol alone, even at doses far above the level needed for growth hormone. None of the peptides tested changed prolactin, TSH, LH or FSH. So the selectivity claim is real published science, but it is animal science. No human study has repeated it.
Will ipamorelin build muscle or help me lose fat?
No study in people has tested that. The muscle and bone findings come from rats given steroids that waste tissue, where ipamorelin restored some muscle force and bone building. Rats are not a body composition trial. Working the other way, mice given secretagogues of this type gained body fat and ate more, by a route that did not involve growth hormone. So the animal picture on fat is not the one the marketing suggests.
Is ipamorelin safe?
Nobody can answer that properly. In the surgery trial, side effects were common in both groups. They were no worse on ipamorelin than on placebo. But that was one small study over a few days. There is no long term human safety data. FDA notes an immune reaction risk with compounded versions and reports of serious adverse events, including death, in published intravenous use. Animal work also flags more insulin release and more appetite.
What should I ask a doctor about ipamorelin?
Ask what problem you are actually trying to fix, and whether a tested treatment exists for it. Ask for baseline blood work, including blood sugar and IGF-1, before anything starts. Ask what would count as a sign to stop. Tell them plainly if you already use it, because it can shift hormone and glucose results and change how your tests read. Ask them to explain the regulatory position, since ipamorelin is not an approved medicine.

References

  1. 1.Gobburu JV, et al. (1999). Pharmacokinetic-pharmacodynamic modeling of ipamorelin, a growth hormone releasing peptide, in human volunteers. Pharmaceutical research. PMID: 10496658. DOI: 10.1023/a:1018955126402.
  2. 2.Beck DE, et al. (2014). Prospective, randomized, controlled, proof-of-concept study of the Ghrelin mimetic ipamorelin for the management of postoperative ileus in bowel resection patients. International journal of colorectal disease. PMID: 25331030. DOI: 10.1007/s00384-014-2030-8.
  3. 3.Raun K, et al. (1998). Ipamorelin, the first selective growth hormone secretagogue. European journal of endocrinology. PMID: 9849822. DOI: 10.1530/eje.0.1390552.
  4. 4.Andersen NB, et al. (2001). The growth hormone secretagogue ipamorelin counteracts glucocorticoid-induced decrease in bone formation of adult rats. Growth hormone & IGF research. PMID: 11735244. DOI: 10.1054/ghir.2001.0239.
  5. 5.Svensson J, et al. (2000). The GH secretagogues ipamorelin and GH-releasing peptide-6 increase bone mineral content in adult female rats. The Journal of endocrinology. PMID: 10828840. DOI: 10.1677/joe.0.1650569.
  6. 6.Greenwood-Van Meerveld B, et al. (2012). Efficacy of ipamorelin, a ghrelin mimetic, on gastric dysmotility in a rodent model of postoperative ileus. Journal of experimental pharmacology. PMID: 27186127. DOI: 10.2147/JEP.S35396.
  7. 7.Dominikowski A, et al. (2026). The emerging landscape of performance-enhancing peptides modulating GH-IGF1 axis: bridging the gap between clinical evidence and patient self-administration. Frontiers in endocrinology. PMID: 42395176. DOI: 10.3389/fendo.2026.1822475.
  8. 8.Lall S, et al. (2001). Growth hormone (GH)-independent stimulation of adiposity by GH secretagogues. Biochemical and biophysical research communications. PMID: 11162489. DOI: 10.1006/bbrc.2000.4065.
  9. 9.Adeghate E, Ponery AS (2004). Mechanism of ipamorelin-evoked insulin release from the pancreas of normal and diabetic rats. Neuro endocrinology letters. PMID: 15665799.

This content is for educational purposes only. These compounds are intended for research use. Nothing here is medical advice.