Hexarelin is a lab-made peptide, six amino acids long, that triggers a strong release of growth hormone from the pituitary gland. It was built in the early 1990s by modifying GHRP-6, the original growth hormone-releasing peptide, and studied mainly by researchers in Turin, Italy.[1][2] It acts on the ghrelin receptor and, unusually, also binds CD36, a receptor in the heart.[12] We found no country where it is approved as a medicine.
This profile covers how hexarelin works, what human studies found, why its effect fades with daily use, the heart research, side effects, doses studied, how it compares with related peptides, and its legal status.
What is hexarelin?
Hexarelin was made by swapping one amino acid in GHRP-6 (tryptophan) for a modified version, which made it active by mouth, though absorption by mouth rarely exceeds 1%.[1] WADA lists it under its other name, examorelin.[19]
Like GHRP-6 and GHRP-2, it belongs to the growth hormone-releasing peptides (GHRPs), which act on the ghrelin receptor and work alongside the brain’s own growth hormone-releasing hormone (GHRH).[7]
How hexarelin works in people
Several small studies in healthy volunteers, from Italy and the UK, mapped its effects:
- Strong growth hormone release: in 12 young volunteers, 1 mcg/kg IV released about twice as much growth hormone as the same dose of GHRH, and the response was very reproducible.[2]
- Dose and timing: in 12 healthy men, growth hormone peaked about 30 minutes after an IV dose and returned to baseline within 4 hours. The response was close to its maximum at 2 mcg/kg.[3]
- Routes: judged by the growth hormone response compared with IV, the biological bioavailability was about 77% under the skin, 4.8% in the nose and 0.3% by mouth.[2]
- Compared with GHRP-2: in a head-to-head study in Turin, hexarelin and GHRP-2 released similar amounts of growth hormone and raised prolactin, ACTH and cortisol to a similar degree.[4]
Desensitization with long-term use
The main limitation of hexarelin is that its effect fades with repeated use. A 1997 review noted that the whole GHRP class shows partial desensitization, more with continuous infusion than with intermittent doses.[7]
- Older adults (UK): 12 healthy older adults injected 1.5 mcg/kg under the skin twice daily for 16 weeks. The total growth hormone released by a test dose fell from 19.1 to 13.1 (micrograms per liter over hours) after one week and to 10.5 by week 16, about 45% lower. Four weeks after stopping, it was back to baseline.[8][9] IGF-1, body fat, lean mass and bone density did not change significantly.[8]
- Children (Israel): in seven short children using a nasal spray three times daily, the growth hormone response roughly halved after 7 days and stayed lower for 6 months. Growth speed still rose, from 5.3 to 7.4 cm a year, and the response partly recovered 3 months after stopping.[11]
Heart research and CD36
Hexarelin is the GHRP most studied for the heart:
- CD36 discovery (Canada): researchers in Montreal found hexarelin binds CD36 in rat heart tissue. In isolated hearts it raised coronary artery pressure, an effect missing in hearts from mice lacking CD36.[12]
- Heart attack model (mice): 21 days of hexarelin after a heart attack improved pumping function and reduced scarring in an Australian study.[13]
- Bypass surgery (people): in a study of 24 men with coronary disease, split between hexarelin, GHRH, growth hormone and placebo, a single 2 mcg/kg IV dose of hexarelin during surgery raised ejection fraction and cardiac output within 10 minutes, lasting up to 90 minutes. GHRH and growth hormone itself had no such effect, suggesting a direct action on the heart.[14]
- Heart failure (people): in 13 patients with severe heart weakness, one IV dose raised ejection fraction in those with ischemic cardiomyopathy (from about 23% to 26%) but not in those with dilated cardiomyopathy.[15]
All human heart data come from single doses. No trial has tested hexarelin as an ongoing heart treatment.
Hexarelin side effects
Published studies are short and small, so data on side effects are limited. The clearest effects are on other hormones:
- Prolactin and cortisol: in healthy men, prolactin rose by up to 180% and cortisol by about 40% at higher IV doses. A low dose combined with GHRH caused a large growth hormone release with no rise in cortisol.[5]
- Sleep: in seven young volunteers, four night-time doses reduced deep sleep and raised growth hormone, prolactin, ACTH and cortisol overnight.[6]
- Long-term use: over 16 weeks, the cortisol response to each injection shrank rather than grew, prolactin did not climb further, and 24-hour urine cortisol did not change.[10]
We found no FDA safety review of hexarelin; it does not appear on FDA’s compounding nomination or safety-risk lists.[16][17][18] Products sold online have no quality oversight.
Hexarelin dosage: what has been studied
| Setting | Dose |
|---|---|
| Healthy adults, single IV dose | 0.5 to 2 mcg/kg[3] |
| Under the skin, single dose | 1.5 or 3 mcg/kg[2] |
| Older adults, 16 weeks | 1.5 mcg/kg under the skin twice daily[8] |
| Short children, 6 to 10 months | 60 mcg/kg nasally three times daily[11] |
| By mouth, single dose | 20 or 40 mg[2] |
No dose has been shown to improve muscle, fat or performance. Doses promoted online come from forums and sellers, not trials. For converting milligrams to syringe units, see our peptide calculator.
Hexarelin vs GHRP-6, GHRP-2 and ipamorelin
- GHRP-6 is the parent peptide; hexarelin was built from it.[1]
- GHRP-2 matched hexarelin for growth hormone and stress hormones head to head.[4]
- Ipamorelin proved more selective; in pigs it released growth hormone without raising ACTH or cortisol, even at high doses.[22]
Our GHRP-2 vs GHRP-6 vs hexarelin comparison compares them side by side, and more compounds are on our growth hormone peptides page.
Is hexarelin legal?
- Not approved: we found no FDA approval for hexarelin.
- Compounding: hexarelin does not appear on FDA’s 503A list (updated May 2026), its 503B list (updated March 2025) or its list of substances with significant safety risks.[16][17][18] Because it is on none of these lists, it falls outside FDA’s interim compounding policies, which cover only certain nominated substances.
- Banned in sport: WADA lists “examorelin (hexarelin)” by name among growth hormone-releasing peptides, prohibited at all times.[19] A Moscow anti-doping lab found hexarelin is broken down heavily and detected its fragments in urine after the parent drug had cleared.[20]
This is general information, not legal advice; rules differ by country and change over time.
