What is Ipamorelin?

What sources report

Ipamorelin was called the first selective growth hormone secretagogue when Novo Nordisk researchers described it in 1998.¹ Since then the record has stayed mostly in animals: PubMed indexes two clinical trials, and a larger third trial finished without posting results.³²¹ Researchers can find Ipamorelin for sale as a 10 mg research vial.

How it works

Ipamorelin activates the ghrelin receptor, also called growth hormone secretagogue receptor 1a (GHS-R1a), the receptor for ghrelin, a hormone that stimulates appetite.²²³¹⁴ FDA's 2024 review describes it acting mainly on ghrelin receptors in GHRH-producing nerve cells of the hypothalamus and on the growth hormone-making (somatotroph) cells of the pituitary.² Because it works through the pituitary, FDA says it would not be expected to raise growth hormone in people whose growth hormone-making cells are absent or badly damaged.²

Its reputation for selectivity rests on pig studies. In conscious swine, ipamorelin did not lift ACTH or cortisol above the levels GHRH produced, even at doses far beyond those needed for a growth hormone response, while GHRP-6 and GHRP-2 raised both; none of the compounds changed FSH, LH, prolactin or TSH.¹ A 2026 review also describes it as sparing cortisol and prolactin, but the human dose study's abstract reports growth hormone results only.⁹¹³

Human studies

Helsinn Therapeutics sponsored both bowel-surgery trials, and FDA quotes a 2020 review saying development stopped after disappointing results.²²²¹²

Animal and lab studies

What has not been shown

No published trial has given ipamorelin under the skin, used it for longer than about 10 days, or tested it for muscle, fat loss, sleep, skin, hair or aging, and no trial has paired it with CJC-1295.²³ A PubMed search for ipamorelin with hair or alopecia returns no records; Peptides and skin and hair covers what has been studied.²⁴ Recovery claims rest on animal work and one negative human trial.¹⁴¹⁸⁴ Peptides and muscle growth and Peptides and healing and recovery map those searches. Other goals:

• Fat loss: the animal data point the other way, with more body fat in mice and more food intake and weight gain in rats.¹⁶¹⁴ See Peptides and weight loss.
• Sleep: no sleep trial exists, and insomnia was more common on ipamorelin (10.7%) than on placebo (5.2%) in the bowel-surgery trial.²³ See Peptides and sleep.
• Blood sugar: high blood sugar at discharge was more common with ipamorelin (14.3% versus 8.6%), even though it raised insulin release from rat pancreas tissue.²²⁵ See Peptides and blood sugar.
• Testosterone: ipamorelin did not change LH or FSH in swine, and a 2020 review found too few clinical data on growth hormone secretagogues in men with low testosterone.¹²⁶ See Peptides and testosterone.

How it compares

GHRP-6 and GHRP-2 act on the same receptor with similar or greater growth hormone potency in animals, but both raised ACTH and cortisol in swine.¹

CJC-1295 No DAC mimics GHRH and works through a different receptor. The two are often marketed together, as in CJC-1295 + Ipamorelin, but no clinical trial has tested the pair.²³

Sermorelin (Geref) is the only growth hormone secretagogue FDA ever approved to treat short stature from growth hormone deficiency in children, and none is approved to treat the deficiency in adults.² Tesamorelin, a GHRH analog, is approved for HIV-associated lipodystrophy.¹⁹ HGH replaces growth hormone directly and works without a functioning pituitary.²

Side effects

Human safety data come almost entirely from one trial, in which 114 adults received IV ipamorelin or placebo for up to 7 days after bowel resection; FDA's 2024 review gives the details.⁴²

Nausea, vomiting and abdominal distention were the most common events, at similar rates in both groups and numerically lower with ipamorelin.² As FDA summarizes the study, the authors judged most events mild to moderate and generally related to the surgery or the underlying disease, and most serious events came after treatment ended.² Two patients on ipamorelin, both operated on for colon cancer, developed leaks where the bowel was rejoined and later died; FDA says it is unclear whether the deaths were related to ipamorelin.²

FDA notes that the 1999 study in healthy men did not mention any adverse events.² FDA's adverse event database held two non-serious reports through September 30, 2023, both with compounded products: watery eyes and headache after a nasal spray, and elbow joint pain after injections of ipamorelin with sermorelin.²

Warnings FDA raises

• Growth hormone effects: risks on growth hormone labels may also apply, including tumor growth, glucose intolerance and diabetes, raised pressure in the skull, fluid retention, low adrenal or thyroid function and pancreatitis; FDA is concerned that similar risks could apply to ipamorelin.²
• Immune reactions: peptides can clump, and peptide-related impurities could provoke immune responses to injected ipamorelin.⁶²
• Heart rhythm: the approved ghrelin agonist macimorelin carries a QT prolongation risk, and FDA says the data are too limited to rule out a similar concern.²
• Missing safety studies: FDA found no published acute, repeat-dose, genetic toxicity, reproductive or cancer studies of ipamorelin.²
• Pregnancy and reward effects: FDA found no reproductive toxicity studies of ipamorelin; in mice, ghrelin harmed fertilization, implantation and embryo development, and FDA notes that ghrelin receptors in brain reward areas modulate responses linked to drugs of abuse in animal studies.²

Dosage information

No human dose of ipamorelin is established.²¹⁹ Its only human dosing data come from short IV studies, and FDA found no safety or effectiveness data for injection under the skin.² A 2026 primer for sports medicine physicians adds that the indications, dosing, frequency and duration of treatment remain unknown.¹⁹

Published studies used these amounts:

These amounts describe what researchers gave under study conditions and are not guidance for anyone. Background on reading study doses is in Peptide dosage basics.

Reconstitution and storage

No FDA label exists for ipamorelin, so there are no official mixing or storage instructions.² The figures available are chemical-supplier data that FDA relayed in its 2024 review:

• Freeze-dried free base: reported stable for 3 weeks at room temperature, with long-term storage kept dry below -18 °C, because moisture lowers the stability of freeze-dried peptides.²
• After dissolving: reported stable for 2 to 3 weeks at 4 °C and 3 to 4 months at -20 °C; the acetate salt as a solid, up to 4 years at -20 °C.²
• Solubility in water: about 5 mg/mL for the acetate but only 0.0032 mg/mL for the free base.²

The vial listing does not state which salt form it holds, so the certificate of analysis is the place to confirm it before choosing a diluent. FDA links heat, pH and concentration changes to aggregation, a possible trigger of immune reactions.² Lab steps and the concentration math are in How to reconstitute a peptide vial, the Reconstitution calculator and How to store peptides.

Regulatory status

United States

No FDA-approved drug contains ipamorelin or ipamorelin acetate, and neither form has a USP or National Formulary monograph.² FDA evaluated both forms on its own initiative for growth hormone deficiency and postoperative ileus.² Its evaluation dated August 19, 2024 proposed keeping them off the 503A bulks list, citing poor physical and chemical characterization, missing endotoxin testing, safety concerns and no data supporting effectiveness.² On October 29, 2024, its advisory committee voted 0 yes, 12 no and 1 abstain on each form, with members citing too little information on safety and efficacy.⁸

Ipamorelin acetate has been in Category 2 under FDA's interim policy for outsourcing facilities since September 29, 2023.⁶ FDA's reasons include possible immune reactions, unnatural amino acids that make the peptide harder to characterize, and a published study with serious adverse events, including death, after IV use.⁶ FDA's page, marked current as of April 22, 2026, still listed it when checked on October 25, 2026.⁶

Outsourcing facilities reported compounding ipamorelin injections from 2017 to 2020 and none since.² FDA warning letters dated August 24, 2026 named two research-labeled blends of tesamorelin and ipamorelin as unapproved new drugs. FDA also cited bacteriostatic water marketed alongside a 'peptide guide' and a 'peptide calculator' as providing the means to prepare an injectable drug for people.¹⁰¹¹

Other countries and sport

FDA's 2024 search found no ipamorelin monograph in the European, Chinese, Indian or Japanese pharmacopeias and no European Medicines Agency listing. It also reports that Australia added ipamorelin to its Poisons Standard as a performance and image enhancing drug, so possession without authority is illegal there.² WADA's 2026 Prohibited List bans ipamorelin at all times, in and out of competition, under S2.2.4 (growth hormone releasing factors), in a separate group from GHRH analogues such as CJC-1295.⁷ Anti-doping labs can detect it and its metabolites in urine.¹²²