Ipamorelin

What is ipamorelin?

Growth hormone release from the pituitary can be stimulated through two separate receptor pathways: the GHRH receptor, to which GHRH from the hypothalamus binds, and the ghrelin receptor (growth hormone secretagogue receptor, GHS-R1a), to which the hunger hormone ghrelin from the stomach binds. Ipamorelin uses the second pathway. The molecule introduced by Novo Nordisk researchers in 1998 is made up of five amino acids and contains amino acids not found in nature; it was derived from the older secretagogue peptides (GHRP-6, GHRP-2) and designed as a candidate that releases GH with similar potency while stimulating fewer other hormones. ^[1]

In healthy volunteers its terminal half-life is about 2 hours, and its effect starts and fades as a single GH wave after administration. ^[2] In this respect it differs from CJC-1295, whose action is measured in days; the sale of the two together rests on this difference, but combined use has never been studied in humans. Details: CJC-1295, CJC-1295 or ipamorelin?

Ipamorelin was considered by the developing company as a drug candidate in areas such as growth retardation; later, Helsinn took the molecule into development for the stoppage of bowel movement after surgery (postoperative ileus). ^{[6] [4]} It was not licensed in any area. What the “research peptide” label means is covered in a separate guide: What does research peptide mean?

Which human studies exist?

Published human data consist of one volunteer study and one patient trial; a second patient trial was completed but no results were published. None measures muscle, fat, sleep, performance or aging outcomes.

The authors of the Beck study conclude that ipamorelin was well tolerated and state, as limitations, that the study was small and included patients with very different underlying diseases. ^[3] This study is the only published trial asking whether ipamorelin works in a disease, and the answer is negative; on this site the relevant line is therefore graded E (“no benefit shown”). The GH rise in the volunteer study is a laboratory value: a single GH wave in a healthy person is not a measured benefit for muscle mass, fat percentage, sleep or aging. ^[2]

What did animal studies show?

Almost all positive findings on ipamorelin come from animal experiments, and most were conducted by researchers at the company that developed the molecule.

• Selectivity (1998): In rat pituitary cells, in anesthetized rats and in conscious pigs, ipamorelin released GH with a potency similar to GHRP-6 and GHRP-2. In pigs it did not change FSH, LH, prolactin and TSH levels; unlike GHRP-6 and GHRP-2, it also did not markedly raise ACTH and cortisol. The authors therefore described ipamorelin as the “first selective” growth hormone secretagogue. ^[1] This selectivity is the argument most often used in promoting ipamorelin; however, it has not been confirmed with the same measurements in humans.
• Bone lengthening (1999): In adult female rats, ipamorelin given three times a day for 15 days increased the lengthening rate of the tibia and body weight gain dose-dependently; total IGF-1 and bone turnover markers did not change. The authors wrote that any place in the treatment of children with growth retardation would need to be shown in future clinical studies. ^[6]
• Bone mineral content (2000): In young adult female rats, ipamorelin and GHRP-6 given continuously for 12 weeks increased bone mineral content measured by DXA; however, the increase came from growth of the bones, and volumetric bone density did not change. ^[7]
• Steroid-induced loss (2001): In adult rats given methylprednisolone for three months, ipamorelin given at the same time counteracted the fall in maximum contraction force of the calf muscle and the decrease in bone formation. ^[8]
• Bowel after surgery (2009): In rats subjected to laparotomy and intestinal manipulation, intravenous ipamorelin shortened the time to the first bowel movement; two days of repeated administration improved fecal output, food intake and weight gain. The authors suggested this might be useful in patients with postoperative ileus; the human trial above did not confirm this suggestion. ^{[9] [3]}
• Insulin release (2004): In pancreatic tissue of normal and diabetic rats, ipamorelin significantly increased insulin release; the effect was explained through calcium channel and adrenergic receptor pathways. ^[10] This finding has not been studied in humans, and the direction of its effect on blood sugar is uncertain.

The general limits in carrying animal data over to humans are also discussed on the BPC-157 and TB-500 pages: BPC-157, TB-500.

What are the risks?

There are no long-term safety data; the longest human administration was 7 days after surgery. ^[3] What is known comes from regulatory assessments, the single patient trial and substances stimulating the same hormone pathway.

• The FDA’s serious adverse event note: The FDA writes that, in a published study, serious adverse events including death were described when ipamorelin was given intravenously for gastrointestinal motility; it states that there is no safety information for other injection routes and that it lacks sufficient information to know whether the drug would cause harm by those routes. ^[11] The abstract of the Beck et al. (2014) study does not mention deaths, reports the frequency of any adverse event as higher in the placebo group (94.8% vs 87.5%), and concludes that ipamorelin was well tolerated. ^[3] The FDA page does not state whether the events were attributable to the drug; in surgical patients, death is an outcome that can also occur independently of the drug.
• Blood sugar: Growth hormone reduces insulin sensitivity; ipamorelin has also been reported to stimulate insulin release in rat pancreas. ^[10] The same FDA list records, for GHRP-6, a rise in blood sugar due to reduced insulin sensitivity, and for GHRP-2, with a note that causality was not established, an increase in insulin requirement. ^[11]
• Heart: For ibutamoren (MK-677), from the same class, the FDA writes that a study in patients recovering from hip fracture was stopped early because of a congestive heart failure signal. ^[11] This finding does not belong to ipamorelin; it shows the type of risk that can be seen with ghrelin receptor agonists.
• Product quality and immune response: According to the FDA, products containing ipamorelin acetate may carry a risk of immune response (immunogenicity) because of aggregation and peptide-related impurities; the unnatural amino acids add to the complexity of characterizing the active substance. ^[11] In an unlicensed product, whether the content really is ipamorelin and its purity have not been verified.
• Appetite: The ghrelin receptor is the receptor of the hunger signal; anamorelin, which stimulates the same receptor, was developed for appetite and weight gain in cancer cachexia. The effect of ipamorelin on appetite in humans has not been measured; in rats, repeated administration increased food intake. ^[9]

The general picture of side effects seen with peptides is in a separate guide: Peptide side effects

FDA, WADA and Türkiye: what is the legal status?

United States (FDA)

The FDA evaluates substances nominated for use as bulk ingredients in compounded (pharmacy-prepared) drugs and places those that may present significant safety risks in “category 2.” Ipamorelin acetate has been in category 2 for 503B (outsourcing facilities) since 29 September 2023; it also appears in the same page’s “nominated but withdrawn” table, where the FDA separately notes that the substance is in category 2 under the 503B interim policy. ^[11] This list is not a drug approval; it concerns the use of the substances in compounding. There is no approved medicine containing ipamorelin in the United States.

Sport (WADA)

In WADA’s list in force from 1 January 2026, under S2.2.4 “growth hormone releasing factors,” ipamorelin appears by name among growth hormone secretagogues and their mimetics (together with anamorelin, ibutamoren, lenomorelin/ghrelin and macimorelin). Substances in section S2 are prohibited at all times, in and out of competition. ^[12]

Türkiye

In the TİTCK (Turkish Medicines and Medical Devices Agency) Licensed Human Medicinal Products List dated October 16, 2026, there is no product with ipamorelin as the active substance. ^[13] Article 19 of Law No. 1262 on Pharmaceutical and Medicinal Preparations (İspençiyari ve Tıbbi Müstahzarlar Kanunu) punishes with imprisonment of one to five years those who manufacture unlicensed preparations and those who knowingly sell, offer for sale or have sold preparations manufactured in this way; importing preparations made abroad for commercial purposes without a license counts as smuggling. ^[14]

The general legal framework for peptides in Türkiye and other countries is in a separate guide: Are peptides legal?

Limits of this guide

This page summarizes the published human and animal data on ipamorelin and the decisions of official bodies. It does not give dose, cycle, preparation, administration technique or product sourcing information; the administrations in the studies are only the protocol of that study. A health problem related to the growth hormone axis is a condition that needs to be measured and treated and requires physician assessment.