Muscle & Performance
Hexarelin
aka Examorelin · EP-23905 · Hexarelin acetate · hexarelin · hexa
Grade
An old experimental peptide that triggers a growth hormone burst, but the body quickly adapts and it was never approved as a medicine.
- Class
- Synthetic hexapeptide growth hormone secretagogue (GHRP-6 analogue); GHS-R1a and CD36 agonist
- Evidence
- Grade C · Early / limited human data
- Sport / WADA
- Prohibited at all times under WADA Section S2 (Peptide Hormones, Growth Factors, Related Substances and Mimetics). Hexarelin (examorelin) is explicitly named as a GH-releasing peptide/growth hormone secretagogue.
- Last reviewed
- 2026-06
Grade C · Early / limited human data
Why this grade
Real human pharmacology data exist: multiple short-term studies confirm hexarelin triggers a dose-dependent growth-hormone spike in healthy volunteers, the elderly, and GH-deficient adults and children. Development reached Phase 2 but was never licensed anywhere. The GH effect desensitises with repeated dosing, and there are no long-term outcome trials showing it builds muscle, improves cardiac endpoints, or delivers any clinically meaningful benefit. Early, short and incomplete: a C, not a B.
What is it?
Hexarelin is a lab-made peptide that tells the pituitary gland to release growth hormone, the body's natural building-and-repair signal. In the 1990s scientists hoped it could help children with severe short stature or adults who don't make enough of their own. After a few weeks of regular use the body stops responding as strongly, so the effect fades. It was tested in people but never became an approved medicine. Today it's sold online as an unlicensed 'research chemical', not as something proven safe or effective for building muscle.
Like a doorbell that triggers an instant answer from the growth-hormone gland the first few times you press it. Keep pressing and the gland stops coming to the door. Impressive in a one-off lab demo, unreliable as a long-term plan, and it never passed medical testing.
How is it meant to work?
Hexarelin is an agonist at the growth hormone secretagogue receptor (GHS-R1a, the ghrelin receptor) in the anterior pituitary and hypothalamus, evoking pulsatile release of endogenous growth hormone. Acutely, it also raises ACTH, cortisol and prolactin. It binds CD36, a scavenger receptor in cardiac and vascular tissue, producing cardiovascular effects that appear independent of GH release. Repeated administration causes partial, reversible desensitisation of the GH response.
What's it studied for?
Research contexts. Not proven uses, and not recommendations.
Does the human evidence stack up?
Real but early and incomplete. Single-dose human studies from the 1990s clearly show hexarelin produces a strong, dose-dependent growth-hormone spike in healthy volunteers, the elderly, and GH-deficient adults and children, and it was studied as a diagnostic provocation agent. The GH effect desensitises (tachyphylaxis) with repeated dosing and recovers after a washout, a significant limitation for any sustained use. A small number of cardiac studies explored CD36-mediated, GH-independent cardioprotection, though the cardiac case rests mostly on animal data. Development reached Phase 2 but the compound was never licensed anywhere. There are no robust controlled trials demonstrating that hexarelin increases muscle mass, strength or athletic performance in healthy people.
What could go wrong?
- !Never approved as a medicine in any country; development stalled at Phase 2
- !GH response desensitises with repeated use, undermining any sustained benefit
- !Acutely raises ACTH, cortisol and prolactin. Not a selective GH stimulus
- !No long-term human safety data. Unknown effects of chronic GH/IGF-1 elevation and theoretical risks of abnormal tissue growth
- !Sold as an unregulated 'research chemical' with no guarantee of identity, purity, sterility or dose
- !Marketed for muscle-building despite no human evidence supporting that use
- !Prohibited in sport at all times by WADA as a growth hormone secretagogue
Is it legal in the UK?
Not a licensed medicine in the UK. Hexarelin holds no MHRA marketing authorisation and is not an approved or prescribed drug. It is an investigational compound whose development was abandoned. It is sold online as an unlicensed 'research chemical' labelled 'not for human consumption'. Selling or supplying it for human medicinal use, or marketing it with health or muscle-building claims, engages the Human Medicines Regulations 2012, and the MHRA enforces action against such sales. It is not a controlled drug under the Misuse of Drugs Act 1971.
Sources
- 01Growth hormone-releasing activity of hexarelin in humans: a dose-response study — Ghigo E, Arvat E, et al., European Journal of Clinical Pharmacology (1994)
Human dose-response study establishing hexarelin's GH-releasing activity.
- 02CD36 mediates the cardiovascular action of growth hormone-releasing peptides in the heart — Bodart V, Febbraio M, et al., Circulation Research (2002)
Identifies CD36 as the receptor behind hexarelin's GH-independent cardiovascular effects (largely preclinical).
- 03Does desensitization to hexarelin occur? — Rahim A, Shalet SM, Growth Hormone & IGF Research (1998)
Documents partial, reversible desensitisation of the GH response with repeated hexarelin administration in the elderly.
- 04Hexarelin growth hormone secretagogue / GHRP literature (PubMed search), PubMed (1998)
Search link for the broader hexarelin/GHS literature; provided in place of a single uncertain review identifier.
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