Ipamorelin vs sermorelin
Last updated: October 2, 2026 · 6 min read · By the Grey Peptides Editorial Board
- Both release the body's own growth hormone, by different doors: sermorelin copies the first 29 amino acids of growth hormone-releasing hormone, while ipamorelin acts like ghrelin on the growth hormone secretagogue receptor.
- Sermorelin was an approved drug, Geref, for diagnosing and treating growth hormone deficiency in children; both forms were discontinued. Ipamorelin was never approved, and its one phase 2 trial found no benefit.
- No study has compared them directly. Both are banned in sport under S2.2.4 of WADA's 2026 List, and as of October 2, 2026 neither is an FDA-approved drug on the market.
Side by side
Sermorelin Medium and ipamorelin Medium are both called growth hormone secretagogues, substances that make the pituitary release its own growth hormone rather than supplying it. They act on different receptors. WADA's 2026 Prohibited List makes the distinction itself: it names sermorelin among the growth hormone-releasing hormone (GHRH) analogues and ipamorelin among the growth hormone secretagogues that mimic ghrelin, both in section S2.2.4 1. The table is read from our encyclopedia entries.
| Field | Ipamorelin | Sermorelin |
|---|---|---|
| Encyclopedia entry | Ipamorelin Full entry | Sermorelin Full entry |
| Molecule class | Peptide | Peptide |
| Category | Growth Hormone | Growth Hormone |
| FDA status | Discontinued | Discontinued |
| Approved elsewhere | None recorded | None recorded |
| Evidence grade | Medium | Medium |
| Half-life | ≈ 2 hours | Not established in our sources |
| Formula | C38H49N9O5 | C149H246N44O42S |
| Molecular weight | 711.9 g/mol | 3,357.9 g/mol |
| WADA 2026 | Prohibited at all times (S2.2.4) | Prohibited at all times (S2.2.4) |
| WADA 2027 | Prohibited at all times (S2.2.4) | Prohibited at all times (S2.2.4) |
| In one line | A ghrelin-receptor agonist that released growth hormone without raising cortisol in pigs; in people it has one dosing study and a phase 2 surgery trial that found no benefit. Never approved. | GHRH's first 29 amino acids, sold in the US as Geref (approved 1990 and 1997) to test and treat childhood growth hormone deficiency until it was discontinued, not for safety reasons. |
| Mechanism | Agonist at the ghrelin (GHRP) receptor that releases growth hormone with a potency close to GHRP-6's in rat pituitary cells and animals. In pigs it did not raise ACTH or cortisol even at more than 200 times its effective dose, unlike GHRP-6 and GHRP-2; that selectivity has not been measured in a published human study. As a ghrelin mimetic it speeds gut transit in rodents. | GHRH receptor agonist: the 29-amino-acid active fragment of GHRH, which stimulates growth hormone secretion from the anterior pituitary. Used as a 1 µg/kg intravenous test of pituitary reserve (a normal response cannot exclude hypothalamic deficiency) and, as Geref, as a nightly treatment for children with idiopathic growth hormone deficiency. |
| Sources in the entry | 15 | 9 |
| Study cards | 14 | 6 |
| Dosage page | Dosage page | Dosage page |
Sermorelin: a former drug
Sermorelin is GRF(1-29) amide, the active first 29 amino acids of human growth hormone-releasing hormone. It was approved in the US as Geref: a 0.05 mg ampoule for diagnosis in 1990 and 0.5 and 1.0 mg vials in 1997 for children with idiopathic growth hormone deficiency. Both were discontinued, and in 2013 the FDA determined Geref had not been withdrawn for reasons of safety or effectiveness 2.
Its human literature is mostly from that era. A review of its use in children describes an intravenous dose of 1 microgram per kilogram as a rapid and relatively specific diagnostic test for growth hormone deficiency 3. In 16 short children who had not responded to a first test, six days of GHRH(1-29) under the skin raised the growth hormone response to a repeat test in eight of them, helping to separate pituitary from hypothalamic causes 4. Five children given it as a nasal spray all had a prompt rise in growth hormone, peaking at 15 minutes 5.
Ipamorelin: a candidate that stopped
Ipamorelin was developed in the 1990s as a selective secretagogue that released growth hormone with potency similar to the older GHRP-6. Its human data are short. In 40 healthy men given single intravenous infusions at five doses, its kinetics were dose-proportional with a terminal half-life of about 2 hours 6. Its one efficacy trial, a multicentre double-blind phase 2 study in 114 adults recovering from bowel resection, gave intravenous ipamorelin 0.03 mg/kg or placebo twice daily for up to seven days and found no significant benefit on recovery of bowel function 7.
It was never approved. The FDA placed ipamorelin acetate in Category 2 of its 503B list, substances raising significant safety concerns for compounding, on September 29, 2023, and its 503A nomination was withdrawn 2. Most of what is written about its effects on muscle, bone and fat comes from rat studies, which our entry lists.
What the difference in mechanism means
Because they act through different receptors, the two are often combined in gray-market vials, on the theory that a GHRH signal and a ghrelin-type signal add up. Our blends and stacks hub covers that practice; no study has tested either drug in combination with the other in people. On their own, sermorelin's effect depends on a working pituitary that responds to GHRH, which is why it doubled as a diagnostic test, while ipamorelin's selling point in development was that it released growth hormone in pigs without raising ACTH or cortisol, which the older GHRP-6 and GHRP-2 did, according to the discovery work recorded on our entry 2.
Neither has outcome data in adults for the uses they are marketed for online, such as body composition or anti-ageing. The evidence gap is the same for both; it is simply older for sermorelin.
Sport and legal status (as of October 2, 2026)
For tested athletes there is no difference: both are prohibited at all times under S2.2.4 as non-Specified substances 1. For everyone else, neither is an FDA-approved drug on the market. Sermorelin's approvals are historical and its products discontinued; ipamorelin was never approved and sits in Category 2 for outsourcing-facility compounding 2. Neither was among the twelve peptides the FDA removed from 503A Category 2 in April 2026 or the seven its compounding committee considered in July. Products sold online under either name are not regulated drugs, and their contents are not verified.
How the differences add up
Sermorelin has the stronger regulatory history, a real approval for a narrow paediatric use, and a mechanism that depends on the body's own pituitary response. Ipamorelin has a cleaner pharmacological profile in early studies but a failed phase 2 trial and no approval. Neither has modern trials in adults, and no study has compared them. Doses on this page and in the table are those recorded in our entries' sources, not recommendations, and anyone considering either should speak with a doctor first.
Frequently asked questions
Is ipamorelin better than sermorelin?
No study has compared them. Sermorelin was an approved drug (Geref) for children with growth hormone deficiency; ipamorelin was never approved, and its one phase 2 trial, after bowel surgery, found no benefit over placebo.
How do ipamorelin and sermorelin work differently?
Sermorelin copies growth hormone-releasing hormone and acts on its receptor; ipamorelin acts like ghrelin on the growth hormone secretagogue receptor. Both make the pituitary release its own growth hormone.
Are ipamorelin and sermorelin banned in sport?
Yes. WADA's 2026 List names both in section S2.2.4, prohibited at all times.
Related on Grey Peptides
Sources
- World Anti-Doping Agency. Prohibited List 2026, section S2.2.4; read October 2, 2026. WADA
- Grey Peptides dataset records for both compounds (status, half-life and studied doses as sourced on each entry); read October 2, 2026.
- Prakash, A., et al. (1999). Sermorelin: a review of its use in the diagnosis and treatment of children with idiopathic growth hormone deficiency. BioDrugs, 12(2), 139-57. PMID: 18031173
- Bueno, G., et al. (1994). Priming with GHRH (1-29) NH2: an aid in differential diagnosis between hypothalamic and pituitary deficiencies. J Pediatr Endocrinol, 7(4), 309-16. PMID: 7735368
- Borkenstein, M. (1986). The effects of intranasal insufflation of growth hormone releasing factor analogue GRF 1-29 NH2 on growth hormone secretion in children with short stature. Acta Endocrinol Suppl (Copenh), 279, 135-8. PMID: 2877535
- Gobburu, J. V., et al. (1999). Pharmacokinetic-pharmacodynamic modeling of ipamorelin, a growth hormone releasing peptide, in human volunteers. Pharm Res, 16(9), 1412-6. PMID: 10496658
- Beck, D. E., 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. Int J Colorectal Dis, 29(12), 1527-34. PMID: 25331030
Educational information, not medical advice. Each dose in this guide names its source, an approved label or a published study. None is a recommendation for you. An unapproved compound has no established safe or effective human dose, and products sold for “research use only” are not made or tested for people. Talk to a doctor before acting on anything on this site, including before you start, stop or change any medicine or dose.
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