GHRP-6

CNot approvedGH secretagogues (GHRPs) →GH-releasing peptide-6His-D-Trp-Ala-Trp-D-Phe-Lys
In one paragraphGHRP-6 is the first of the growth-hormone-releasing peptides, a synthetic six-amino-acid ghrelin mimic. In studies it raises growth hormone as reliably as the standard insulin tolerance test, which makes it a useful diagnostic; it also stimulates appetite. As with the rest of its class, there is no controlled human trial showing it builds muscle or reduces fat, and it is banned in sport.
Schematic 3D structure of GHRP-6
6 residues · the original GH-releasing hexapeptide · schematic
Overall gradeC Weak
Human trialsDiagnostic studies + small work
Outcomes graded4
Last reviewed3 September 2026
EvidenceWhat it isHow it worksUnknownsMolecule & PKRegulationQuestionsReferences

What the human research shows

Historically important — it helped map the ghrelin system — and clinically it is a diagnostic-grade GH stimulus, nothing more. The physique reputation has no trial behind it.

MetabolicCardioMuscleHealingNeuroImmuneSexualSkinAgeing

Evidence profile0–5

  • Metabolic & weightC0.7
  • Cardiovascular—0.0
  • Muscle & growthB2.3
  • 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.
OutcomeGradeEffect sizeHuman studiesWhere the evidence comes from
Growth hormone release (diagnostic)BProbableModerateDiagnostic comparison studiesGHRP-6, alone or with GHRH, stimulated growth hormone as sensitively and specifically as the insulin tolerance test for diagnosing adult GH deficiency.1
AppetiteCWeakSmallSmall human studiesAs a ghrelin-receptor agonist it increases hunger; the human appetite data are smaller and less quantified than for GHRP-2.1
Body compositionDNo human evidenceNot measurableNoneNo controlled trial has tested whether repeated GHRP-6 changes muscle or fat in people.1
Safety in humansadverseCWeakSmallDiagnostic useAs a single diagnostic dose, flushing was the only side effect reported. Repeated-use safety is not established.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

GHRP-6 is the original growth-hormone-releasing peptide, a hexapeptide discovered while mapping how the body controls growth-hormone secretion. That work eventually led to the discovery of ghrelin and its receptor.

It is sold on the grey market for muscle and recovery, uses it has never been shown to have in a trial.

How it is thought to work

It activates the GH-secretagogue (ghrelin) receptor, releasing growth hormone and stimulating appetite. A single dose is a clean diagnostic stimulus; chronic use for physique is untested.

What is still unknown

  • Whether repeated dosing does anything to body composition — never tested.
  • Long-term safety and receptor desensitisation.
  • The size and reliability of the appetite effect relative to GHRP-2.

The molecule and how long it lasts

Identity
Formula
C46H56N12O6
Molecular weight
873.0 g/mol
CAS number
Not listed
PubChem
CID 4345065

PubChem record, read 23 September 2026.

Pharmacokinetics
Route
Intravenous bolus (9 healthy men)
Half-life
About 2.5 hours elimination half-life; distribution half-life about 8 minutes

From a published human pharmacokinetic study: Cabrales A, et al. Pharmacokinetic study of growth hormone-releasing peptide 6 (GHRP-6) in nine male healthy volunteers. Eur J Pharm Sci 2013;48:40–46

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

What is GHRP-6 actually good for?
As a diagnostic stimulus for growth-hormone deficiency it performs as well as the standard insulin tolerance test. That is its only evidence-backed use.
Does it build muscle?
No controlled human trial has tested it. Like the rest of the class, it raises growth hormone acutely but has no outcome data for body composition.
How is it different from GHRP-2?
They are close cousins. GHRP-2 has a formal diagnostic approval in Japan and better-quantified appetite data; GHRP-6 is the older molecule and drives hunger somewhat more prominently.

One page per claimed effect

References

  1. 1

Change log

  • 2026-09-03Initial publication. Grade reflects diagnostic-grade GH data and no outcome trials.