Ipamorelin: uses, evidence and status

compound file

The answer, first. A five amino acid ghrelin-receptor agonist and selective growth hormone secretagogue, developed at Novo Nordisk in the 1990s and never approved. The strongest evidence is for acute growth hormone release, graded C — small or open-label human only.

Dose-proportional GH release across five intravenous infusion rates in 40 healthy men, a single peak at 0.67 hours then an exponential decline to negligible ¹.

One study, intravenous, no published subcutaneous human data. Every other use — muscle and bone under steroid load, appetite and weight gain, growth hormone release without a cortisol rise, recovery of gut motility after bowel surgery — grade D or E: animal or mechanism data only, or a claim the human trials have already tested and not supported.

What it is used for

Every use graded on its own evidence, not the compound as a whole. 5 outcomes, ranked by what the human record supports.

#outcome · human · animal · gradewhat the best evidence actually shows

01Acute growth hormone release1 dose-escalation study, 40 men · rat, swinegrade CDose-proportional GH release across five intravenous infusion rates in 40 healthy men, a single peak at 0.67 hours then an exponential decline to negligible ¹. One study, intravenous, no published subcutaneous human data.

02Muscle and bone under steroid loadno trial · 1 controlled rat studygrade DIn glucocorticoid-treated adult rats, 100 µg/kg three times daily for three months raised calf tetanic tension and quadrupled periosteal bone formation against steroid alone ³. No human trial has measured muscle or bone.

03Appetite and weight gainno trial · rat and ferret studiesgrade DRepeat intravenous dosing at 0.1 to 1 mg/kg raised food intake, faecal output and weight gain in post-surgical rats ⁴. In ferrets, 1 to 3 mg/kg cut cisplatin-induced weight loss by about 24% ⁵.

04Growth hormone release without a cortisol risenot measured in humans · swine, ratgrade DIn conscious swine, ipamorelin released GH as effectively as GHRP-6 ⁶. It did not raise ACTH or cortisol at doses more than 200-fold above its GH ED50 ⁶. The human study measured GH only ¹.

05Recovery of gut motility after bowel surgery1 phase 2 RCT, 114 patients · rat modelgrade EThe only randomized human trial. In 114 bowel-resection patients on 0.03 mg/kg twice daily, median time to a tolerated meal was 25.3 against 32.6 hours, P=0.15 ². No separation on key or secondary endpoints ².

gradewhat it means

ARegulatory approval, or multiple adequately-powered trials agreeing with each other

BAt least one well-powered human randomised trial, with the direction replicated

CSmall or open-label human trials only

DAnimal or mechanism data only, with no controlled human outcome

EA claim the human trials have already killed

How it works

The proposed mechanism, in three steps. A mechanism is a reason to run a trial, never a substitute for one.

1targetBinds the ghrelin receptor on pituitary somatotrophs, a different receptor from the GHRH analogs it is usually sold beside ⁶.

2signalOne discrete growth hormone pulse per dose, peaking at 0.67 hours and falling to negligible, at every dose tested ¹.

3effectDownstream tissue outcomes were never measured in humans. In rats, repeat dosing raised bone formation, food intake and weight gain ³⁴.

What it does not do

Claims the current record does not support. Worth knowing before you set expectations.

not supported by the evidence

Builds muscle. No trial has measured it. With growth hormone itself, fat-free mass rose while muscle protein synthesis and strength matched placebo ⁷.
Proven in humans because a trial exists. The one randomized trial tested gut motility after surgery and did not separate from placebo on any efficacy analysis ².
Safe because it is selective. Selectivity over ACTH and cortisol was shown in swine ⁶. FDA lists it in category 2, citing serious adverse events including death ⁸.
Burns fat. No human or animal study has measured fat mass on ipamorelin. In rats, repeat dosing increased body weight rather than reducing it ⁴.

How it is used

What published protocols administered, and what the community reports doing. Descriptive on both counts, and never a recommendation.

routeSubcutaneous injection in community use. Both published human studies used intravenous infusion ¹².

formatLyophilised powder in a research vial, reconstituted before use.

published dosesThe pharmacokinetic study infused 4.21 to 140.45 nmol/kg intravenously over 15 minutes, eight men per dose level ¹. The ileus trial gave 0.03 mg/kg intravenously twice daily for up to seven days ². No subcutaneous human dose has been published.

human pharmacokineticsTerminal half-life about 2 hours after intravenous infusion in healthy men, clearance 0.078 L/h/kg ¹.

reported conventionsAs reported on bodybuilding forums, catalogued in a 2026 review of self-administration, 2025 to 2026 ⁹. The pattern: 200 to 300 µg subcutaneously, two or three injections a day, timed to natural GH pulses ⁹. Usually combined with no-DAC CJC-1295, in cycles of 8 to 12 weeks ⁹. Convention, not guidance.

commonly paired withCJC-1295

This site does not publish protocols to follow. The doses above are what studies administered or what users report, stated as facts about the literature and the market. How protocols are structured, mixing and storage and the reconstitution calculator cover the arithmetic.

What to expect

Where a trial measured it, the trial. Where only the community reports it, that is said out loud.

onsetGrowth hormone peaks 0.67 hours after an intravenous dose and returns to negligible within the same session ¹. In the ileus trial the readout was hours to a tolerated meal, and it did not separate from placebo ². No trial has tracked weeks.

most common reportThe measured result is one short growth hormone pulse per dose ¹. Nothing downstream of that pulse has been measured in a human.

adverse effectsTreatment-emergent events reached 87.5% on ipamorelin against 94.8% on placebo across 114 surgical patients ². FDA cites serious adverse events including death when it was given intravenously for gastric motility ⁸. As reported: fluid retention, myalgia, injection-site reactions ⁹.

the stop signalThe literature names no stop rule. The 2026 clinical review triages fluid retention, dysglycaemia, and prolactin or cortisol changes in people self-administering this class ⁹.

Approval and status

What regulators and sport bodies have actually said, separately from what the evidence shows.

approvalNone. Development ended after a phase 2 trial. Sold as a research chemical ⁸.

FDAIn FDA category 2 of bulk substances that may present significant safety risks, added 29 September 2023 under the 503B interim policy ⁸.

sport [WADA]Prohibited at all times, class S2.2.4 ¹⁰.

sold asresearch chemical

Covered in depth

These reports grade Ipamorelin at length and carry their own verified reference lists.

Fullness Is Not Muscle: What Tesamorelin, CJC-1295 With Ipamorelin, and MOTS-c Actually Do to Body Composition

Three compounds, three different stories, and one measurement problem that explains all of them. The scan moves. The muscle does not.

Check the vial

The grade above describes a molecule studied under controlled conditions. It says nothing about the powder in a particular vial.

That gap is the one part of this market a reader can actually close. How to read a certificate of analysis covers the five measures in five minutes, and the 2026 audit grades vendors on the documents they publish against a rubric printed in full.

Questions we get

What is Ipamorelin used for?

In the published record, two things were tested. A short growth hormone pulse in 40 healthy men ¹. Recovery of gut motility after bowel surgery in 114 patients, where it did not beat placebo ². It is bought for muscle, recovery and sleep. No trial has measured any of those ⁹.

How is Ipamorelin used?

Descriptively. The pharmacokinetic study infused 4.21 to 140.45 nmol/kg intravenously over 15 minutes ¹. The ileus trial gave 0.03 mg/kg intravenously twice daily for up to seven days ².

As reported on forums and catalogued in a 2026 review, 200 to 300 µg subcutaneously, two or three times a day ⁹. In cycles of 8 to 12 weeks ⁹. Convention, not guidance.

How long does Ipamorelin take to work?

For the only measured effect, under an hour. Growth hormone peaks at 0.67 hours after an intravenous dose and is back to negligible in the same session ¹.

Nothing else has been timed, because nothing else has been measured. Reports of results at four, six or eight weeks come from uncontrolled community logs, not from trials.

Does Ipamorelin build muscle?

No trial has measured it. The nearest evidence is a warning. Growth hormone itself was added to 16 weeks of resistance training in older men ⁷.

Fat-free mass rose more, while muscle protein synthesis, creatinine excretion and strength gains matched placebo ⁷. A different oral secretagogue did raise lean mass 1.4 kg in older adults, and body weight by the same 1.4 kg ¹¹.

Why is Ipamorelin on the FDA category 2 list?

FDA added ipamorelin acetate on 29 September 2023 to its list of bulk substances that may present significant safety risks ⁸. Its stated reasons: immunogenicity risk from aggregation and peptide impurities ⁸.

Unnatural amino acids that complicate characterisation ⁸. Published serious adverse events including death when the drug was given intravenously for gastric motility ⁸.

References

Gobburu JV, Agerso H, Jusko WJ, Ynddal L. Pharmacokinetic-pharmacodynamic modeling of ipamorelin, a growth hormone releasing peptide, in human volunteers. Pharm Res. 1999;16:1412-1416. PMID 10496658
Beck DE, Sweeney WB, McCarter MD, et al. Prospective, randomized, controlled, proof-of-concept study of the ghrelin mimetic ipamorelin for the management of postoperative ileus in bowel resection patients. Int J Colorectal Dis. 2014;29:1527-1534. PMID 25331030
Andersen NB, Malmlof K, Johansen PB, et al. The growth hormone secretagogue ipamorelin counteracts glucocorticoid-induced decrease in bone formation of adult rats. Growth Horm IGF Res. 2001;11:266-272. PMID 11735244
Venkova K, Mann W, Nelson R, Greenwood-Van Meerveld B. Efficacy of ipamorelin, a novel ghrelin mimetic, in a rodent model of postoperative ileus. J Pharmacol Exp Ther. 2009;329:1110-1116. PMID 19289567
Lu Z, Ngan MP, Liu JYH, et al. The growth hormone secretagogue receptor 1a agonists, anamorelin and ipamorelin, inhibit cisplatin-induced weight loss in ferrets. Physiol Behav. 2024;284:114644. PMID 39043357
Raun K, Hansen BS, Johansen NL, et al. Ipamorelin, the first selective growth hormone secretagogue. Eur J Endocrinol. 1998;139:552-561. PMID 9849822
Yarasheski KE, Zachwieja JJ, Campbell JA, Bier DM. Effect of growth hormone and resistance exercise on muscle growth and strength in older men. Am J Physiol. 1995;268:E268-E276. PMID 7864103
US Food and Drug Administration. Certain bulk drug substances for use in compounding that may present significant safety risks. Category 2 listing, ipamorelin acetate entry, added 29 September 2023. fda.gov
Dominikowski A, Rekos Z, Olejarz M, et al. The emerging landscape of performance-enhancing peptides modulating the GH-IGF1 axis. Front Endocrinol. 2026;17:1822475. PMID 42395176
World Anti-Doping Agency. The Prohibited List, 2026. Section S2.2.4, growth hormone secretagogues. wada-ama.org
White HK, Petrie CD, Landschulz W, et al. Effects of an oral growth hormone secretagogue in older adults. J Clin Endocrinol Metab. 2009;94:1198-1206. PMID 19174493

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