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Ipamorelin vs Hexarelin: What the Research Shows

Ipamorelin and Hexarelin side by side: what they are, how they are regulated and what is still unknown.

Medically reviewed by Juan Pablo Frías, MD · · DisclosureUpdated
GHRP (ghrelin receptor agonist)Not FDA approved · research chemicalIpamorelinGhrelin-receptor agonist peptide, not FDA-approved; in a randomized trial after bowel resection, median time to first tolerated meal was 25.3 versus 32.6 hours with placebo.[6]Growth hormone+70% searches
Growth hormone releasing peptide (GHRP)Not FDA approved · research chemicalHexarelinSynthetic analog of ghrelin that binds the growth hormone secretagogue receptor; reviews describe strong growth hormone-releasing effects for this drug class.[9]
Quick verdict

Where the research points

Summary of studies, not a recommendation

Consider Ipamorelin if…

  • you want the option with a randomized human trial, though it found no significant difference from placebo (postoperative ileus): median time to first tolerated meal was 25.3 h vs 32.6 h[6]

Consider Hexarelin if…

  • you want a human GH-release study: hexarelin stimulated GH secretion in patients with idiopathic GH deficiency[10]
  • you are tested in sport and want to avoid a WADA-prohibited substance: WADA prohibits growth hormone secretagogues at all times; its list names ibutamoren (MK-677) and ipamorelin (check hexarelin's own status separately)[2]
Ipamorelin is prohibited in tested sport (WADA). Status labels come from public FDA and WADA records; see the sources below.
Side by side

Spec comparison

Showing 9 of 11 fields where the two differ. FDA status, PCAC vote, Jul 2026 are the same or both unknown.

FieldIpamorelinHexarelin
ClassGHRP (ghrelin receptor agonist)Growth hormone releasing peptide (GHRP)
Also calledipa, ipam—
WADAProhibited by WADA (S2.2.4)Ipamorelin is named as a growth hormone secretagogue in S2.2.4, prohibited at all times.No WADA record in our data
Anti-doping detection
  • After nasal dosing, ipamorelin metabolites were still found in urine after the parent drug was gone (samples were collected for 2 days).PMID 25869809
  • A direct-urine screen includes ipamorelin among the peptides it can detect, at 50 to 500 pg/mL.PMID 26578461
None reportedanti-doping literature, as of 2 Oct 2026
Half-life2 hours terminal half-lifeintravenous infusion (15 min) · Pharmaceutical research 1999, PMID 10496658[half-life by route]
Evidence strengthHuman RCT evidence, 4 of 4Strongest: International journal of colorectal disease 2014, PMID 25331030[evidence grade]
Human studies we summarised2 human (2 randomized or controlled) of 12 summarised[n]
Typical study doses[dose range]
Named in FDA warning letters, 2026Yes (24 Aug 2026)Not in the letters we track

Bracketed values are pending a sourced figure. Legal data reflects the regulatory events in our tracker.

Sources

  1. 1FDA warning letters to five research-peptide sellersFDA warning letter (NuScience Peptides; 1 of 5) · 2026fda.govAccessed 2 Oct 2026
  2. 2World Anti-Doping Code International Standard Prohibited List 2026World Anti-Doping Agency · 2026wada-ama.orgAccessed 2 Oct 2026
  3. 3Determination of growth hormone releasing peptides metabolites in human urine after nasal administration of GHRP-1, GHRP-2, GHRP-6, Hexarelin, and Ipamorelin.Drug testing and analysis · 2015PMID 25869809Accessed 2 Oct 2026
  4. 4Simplifying and expanding the screening for peptides <2 kDa by direct urine injection, liquid chromatography, and ion mobility mass spectrometry.Journal of separation science · 2016PMID 26578461Accessed 2 Oct 2026
  5. 5Pharmacokinetic-pharmacodynamic modeling of ipamorelin, a growth hormone releasing peptide, in human volunteers.Pharmaceutical research · 1999PMID 10496658Accessed 2 Oct 2026
  6. 6Prospective, 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 · 2014PMID 25331030Accessed 2 Oct 2026
  7. 7The growth hormone secretagogue receptor 1a agonists, anamorelin and ipamorelin, inhibit cisplatin-induced weight loss in ferrets: Anamorelin also exhibits anti-emetic effects via a central mechanism.Physiology & behavior · 2024PMID 39043357Accessed 2 Oct 2026
  8. 8PubMed search: (hexarelin[tiab]) AND (ipamorelin[tiab])PubMed · 2026pubmed.ncbi.nlm.nih.govAccessed 2 Oct 2026
  9. 9Implications of ghrelin and hexarelin in diabetes and diabetes-associated heart diseases.Endocrine · 2015PMID 25645463Accessed 2 Oct 2026
  10. 10The effect of hexarelin on growth hormone (GH) secretion in patients with GH deficiency.The Journal of clinical endocrinology and metabolism · 1995PMID 7673411Accessed 2 Oct 2026

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