Hexarelin: what the evidence shows

What the human research shows

Real, reproducible endocrinology — a genuine GH spike — that runs into the wall every GH secretagogue hits: the body adapts, the marker stops moving, and no trial ever showed it changes anything you can see or feel. Banned in sport.

Evidence profile0–5

Metabolic & weight—0.0
CardiovascularD0.0
Muscle & growthC1.3
Healing & repair—0.0
Neuro & sleep—0.0
Immune & inflammation—0.0
Sexual & hormonal—0.0
Skin & appearance—0.0
Ageing & longevity—0.0

Each score is confidence × effect size, taken from the best-evidenced benefit in that domain: the grade (A–D) sets the confidence, the measured effect sets the size. Hover a domain to see the outcomes behind it. Adverse effects are excluded and listed separately below.

Outcome	Grade	Effect size	Human studies	Where the evidence comes from
Growth hormone release	CWeak	Moderate	Multiple acute studies + 1 chronic study	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.1
Body composition	DNo human evidence	Not measurable	1 chronic study (n small)	In the only sustained-dosing study, IGF-1, body fat, lean mass and bone density did not change significantly over 16 weeks.1
Cardiac effects	DNo human evidence	Not measurable	Mechanistic only	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.2
Safety in humansadverse	CWeak	Small	Early-phase	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.1

AMultiple good human trials, consistentBSome human trials, mostly consistentCFew or weak human studiesDAnimal or anecdotal onlyeffect size · red = adverse

Literature searched to 3 September 2026. Human studies only; animal and cell work informs the mechanism section and nothing else.

What it is

Hexarelin is one of the original growth-hormone-releasing peptides (GHRPs), a hexapeptide that stimulates growth-hormone secretion by acting on the ghrelin/GH-secretagogue receptor. It was studied in the 1990s as a possible GH-deficiency treatment and diagnostic.

It is sold on the grey market for muscle, recovery and 'anti-ageing', none of which it was ever shown to do in a trial.

How it is thought to work

It activates the GH-secretagogue receptor in the hypothalamus and pituitary, driving pulses of growth-hormone release. Continued exposure desensitises that response — the reason a molecule that clearly 'works' acutely never produced a durable clinical effect.

What is still unknown

Whether any dosing schedule produces a change in body composition or function that a person would notice — untested.
Long-term safety, including the effects of chronic receptor stimulation.
Whether the animal cardiac findings mean anything in people.

The molecule and how long it lasts

Identity

Formula: C47H58N12O6
Molecular weight: 887.0 g/mol
CAS number: 140703-51-1
PubChem: CID 6918297

PubChem record, read 23 September 2026.

Pharmacokinetics

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

Animal data only — no human pharmacokinetic study: Roumi M, et al. Radioimmunoassay for hexarelin and its pharmacokinetic studies. Peptides 1995;16

Regulatory status

European Union

Unauthorised medicinal product

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.

United States

Not approved

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.

United Kingdom

Unlicensed medicine

Not licensed by the MHRA. Selling or supplying it for human use is an offence under the Human Medicines Regulations 2012.

Australia

Prescription-only / unapproved

Not on the ARTG. Supply without a prescription is unlawful; imports are seized.

Canada

Not authorised

No Drug Identification Number; selling it for human use is illegal.

Sport (WADA)

Prohibited at all times

WADA class S2.2: growth-hormone secretagogues and GH-releasing peptides are banned in and out of competition.

Questions people actually ask

Does hexarelin build muscle?

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.

Why does it 'stop working'?

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.

Is it allowed in sport?

No. GH-releasing peptides are prohibited at all times under WADA category S2.

One page per claimed effect

CDoes Hexarelin help with growth hormone release?Multiple acute studies + 1 chronic study
DDoes Hexarelin help with body composition?1 chronic study (n small)
DDoes Hexarelin help with cardiac effects?Mechanistic only
CHow common is safety in humans with Hexarelin?Early-phase

References

1
Rahim A, et al. Growth hormone status during long-term hexarelin therapy.J Clin Endocrinol Metab, 1998;83:1644–164916 weeks; GH response attenuates, IGF-1 and body composition unchanged.
2
Arvat E, et al. Endocrine activities of ghrelin in humans: comparison with hexarelin and GHRH.J Clin Endocrinol Metab, 2001;86:1169–1174Acute GH-releasing potency of hexarelin in people.

Change log

2026-09-03Initial publication. Grade C on a real but self-limiting GH effect and no outcome data.