{"id":"hexarelin","name":"Hexarelin","aliases":["examorelin","EP-23905","GH-releasing peptide"],"url":"https://lyoresearch.com/compounds/hexarelin","class":{"id":"gh-secretagogues","name":"GH secretagogues (GHRPs)","url":"https://lyoresearch.com/classes/gh-secretagogues"},"summary":"Hexarelin is a synthetic six-amino-acid growth-hormone-releasing peptide. Single doses cause a strong, well-documented growth-hormone spike in humans, but the one study of continued use showed the response fades within weeks and that IGF-1 and body composition did not meaningfully change. It was never developed into an approved medicine, and the muscle, fat-loss and cardiac claims made for it have no controlled human evidence.","overall_grade":"C","overall_grade_meaning":"weak human evidence","human_trials":"Early-phase human studies","regulatory_status":"Not approved","molecule":{"formula":"C47H58N12O6","molecular_weight":"887.0","cas":"140703-51-1","pubchem_cid":6918297,"note":null},"pharmacokinetics":{"basis":"animal","route":"Intravenous in human GH-response studies, which report no PK","half_life":"No human pharmacokinetic data. Dog intravenous terminal half-life about 2 hours","licensed_regimen":null,"product":null,"source":{"title":"Roumi M, et al. Radioimmunoassay for hexarelin and its pharmacokinetic studies. Peptides 1995;16","url":"https://pubmed.ncbi.nlm.nih.gov/8545255/"}},"outcomes":[{"outcome":"Growth hormone release","grade":"C","grade_meaning":"weak human evidence","effect_size":"moderate","adverse":false,"human_studies":"Multiple acute studies + 1 chronic study","evidence":"Acute GH release after hexarelin is large and well established. Over 16 weeks of twice-daily dosing the response attenuated and then recovered after stopping — a tolerance effect typical of the class.","references":[{"citation":"Rahim A, et al. Growth hormone status during long-term hexarelin therapy.","where":"J Clin Endocrinol Metab, 1998;83:1644–1649","url":"https://pubmed.ncbi.nlm.nih.gov/9589671/"}],"verbatim":{"text":"chronic hexarelin therapy results in a partial and reversible attenuation of the GH response to hexarelin.","citation":"Rahim A, et al. Growth hormone status during long-term hexarelin therapy.","url":"https://pubmed.ncbi.nlm.nih.gov/9589671/"}},{"outcome":"Body composition","grade":"D","grade_meaning":"no human evidence","effect_size":"not measurable","adverse":false,"human_studies":"1 chronic study (n small)","evidence":"In the only sustained-dosing study, IGF-1, body fat, lean mass and bone density did not change significantly over 16 weeks.","references":[{"citation":"Rahim A, et al. Growth hormone status during long-term hexarelin therapy.","where":"J Clin Endocrinol Metab, 1998;83:1644–1649","url":"https://pubmed.ncbi.nlm.nih.gov/9589671/"}],"verbatim":{"text":"In the present study, the biological impact of this hexarelin schedule on the GH-IGF-I axis seems to be minimal.","citation":"Rahim A, et al. Growth hormone status during long-term hexarelin therapy.","url":"https://pubmed.ncbi.nlm.nih.gov/9589671/"}},{"outcome":"Cardiac effects","grade":"D","grade_meaning":"no human evidence","effect_size":"not measurable","adverse":false,"human_studies":"Mechanistic only","evidence":"Hexarelin binds a receptor (CD36) in the heart and has cardiovascular effects in animals and acute human physiology studies. No controlled trial has tested a clinical cardiac outcome.","references":[{"citation":"Arvat E, et al. Endocrine activities of ghrelin in humans: comparison with hexarelin and GHRH.","where":"J Clin Endocrinol Metab, 2001;86:1169–1174","url":"https://pubmed.ncbi.nlm.nih.gov/11238504/"}]},{"outcome":"Safety in humans","grade":"C","grade_meaning":"weak human evidence","effect_size":"small","adverse":true,"human_studies":"Early-phase","evidence":"Short-term dosing is generally well tolerated in the small studies; transient flushing and mild cortisol/prolactin rises are described. No long-term safety data.","references":[{"citation":"Rahim A, et al. Growth hormone status during long-term hexarelin therapy.","where":"J Clin Endocrinol Metab, 1998;83:1644–1649","url":"https://pubmed.ncbi.nlm.nih.gov/9589671/"}]}],"regions":[{"region":"European Union","status":"Unauthorised medicinal product","note":"No marketing authorisation in any member state. Supplying it for human use is an offence under national medicines law; a 'research use only' label does not change that."},{"region":"United States","status":"Not approved","note":"Not an approved drug and not a dietary-supplement ingredient. Sold as a 'research chemical' outside the medical system; the FDA has warned against several compounds in this class."},{"region":"United Kingdom","status":"Unlicensed medicine","note":"Not licensed by the MHRA. Selling or supplying it for human use is an offence under the Human Medicines Regulations 2012."},{"region":"Australia","status":"Prescription-only / unapproved","note":"Not on the ARTG. Supply without a prescription is unlawful; imports are seized."},{"region":"Canada","status":"Not authorised","note":"No Drug Identification Number; selling it for human use is illegal."},{"region":"Sport (WADA)","status":"Prohibited at all times","note":"WADA class S2.2: growth-hormone secretagogues and GH-releasing peptides are banned in and out of competition."}],"faq":[{"q":"Does hexarelin build muscle?","a":"There is no controlled human evidence that it changes muscle or body composition. The one sustained-dosing study found no significant change in lean mass, fat or IGF-1 over 16 weeks."},{"q":"Why does it 'stop working'?","a":"Like other GH-releasing peptides, continued use desensitises the receptor, so the growth-hormone response fades over weeks. It recovered after stopping in the one study that measured it."},{"q":"Is it allowed in sport?","a":"No. GH-releasing peptides are prohibited at all times under WADA category S2."}],"references":[{"cite":"Rahim A, et al. Growth hormone status during long-term hexarelin therapy.","where":"J Clin Endocrinol Metab, 1998;83:1644–1649","url":"https://pubmed.ncbi.nlm.nih.gov/9589671/","note":"16 weeks; GH response attenuates, IGF-1 and body composition unchanged."},{"cite":"Arvat E, et al. Endocrine activities of ghrelin in humans: comparison with hexarelin and GHRH.","where":"J Clin Endocrinol Metab, 2001;86:1169–1174","url":"https://pubmed.ncbi.nlm.nih.gov/11238504/","note":"Acute GH-releasing potency of hexarelin in people."}],"last_reviewed":"2026-09-03","literature_searched_to":"2026-09-03","changelog":[{"date":"2026-09-03","note":"Initial publication. Grade C on a real but self-limiting GH effect and no outcome data."}],"license":"CC BY 4.0 — cite as “LYO Research” with a link.","methodology":"https://lyoresearch.com/methodology"}