GHRP-2

CApproved (diagnostic, Japan)GH secretagogues (GHRPs) →pralmorelinKP-102GH-releasing peptide-2
In one paragraphGHRP-2, or pralmorelin, is a synthetic six-amino-acid growth-hormone-releasing peptide. It reliably and measurably raises growth hormone, and on that basis is approved in Japan as a diagnostic test for growth-hormone deficiency. Like natural ghrelin it also increases appetite in short human studies. What it does not have is any trial showing it builds muscle, burns fat or improves body composition — the uses it is actually sold for. It is banned in sport.
Schematic 3D structure of GHRP-2
6 residues · GH-releasing hexapeptide (pralmorelin) · schematic
Overall gradeC Weak
Human trialsDiagnostic-grade + small studies
Outcomes graded4
Last reviewed3 September 2026
EvidenceWhat it isHow it worksUnknownsMolecule & PKRegulationQuestionsReferences

What the human research shows

The clearest example in this class of a real, approved use (a one-off diagnostic injection) being stretched into an unproven daily one (physique). The GH spike and the appetite bump are genuine; the body-composition claims have never been tested in a trial.

MetabolicCardioMuscleHealingNeuroImmuneSexualSkinAgeing

Evidence profile0–5

  • Metabolic & weightC1.3
  • Cardiovascular—0.0
  • Muscle & growthA3.3
  • 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)AEstablishedModerateApproval-grade diagnostic studiesGHRP-2 produces a large, reproducible GH rise that cleanly separates GH-deficient from healthy people — the basis of its Japanese approval as a diagnostic agent.1
AppetiteCWeakModerateSmall crossover study (n=7)As a ghrelin mimic, GHRP-2 increased food intake in healthy men in a controlled infusion study — a real acute effect, studied in very few people.2
Body compositionDNo human evidenceNot measurableNoneNo controlled trial has tested whether repeated GHRP-2 changes muscle or fat in humans. The physique claims are extrapolation from the acute GH rise.1
Safety in humansadverseCWeakSmallDiagnostic useAs a single diagnostic dose it is well tolerated, with flushing the main effect. Safety of repeated self-dosing is not established, and it raises cortisol and prolactin more than the most selective secretagogues.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-2 (pralmorelin) is a hexapeptide growth-hormone secretagogue — a synthetic ghrelin mimic. It stimulates a pulse of growth-hormone release and, separately, appetite.

In Japan it is an approved diagnostic: a single injection to test the pituitary's capacity to release growth hormone. Everywhere else it is sold as a physique and 'anti-ageing' research chemical.

How it is thought to work

It activates the GH-secretagogue (ghrelin) receptor in the hypothalamus and pituitary, producing GH release and, via the same system, hunger. A diagnostic test uses one dose; the marketed use is chronic — a very different proposition that has not been studied for benefit.

What is still unknown

  • Whether repeated dosing changes body composition at all — never tested.
  • Long-term safety, including desensitisation and the effect of raised appetite.
  • Whether the cortisol and prolactin rises matter with chronic use.

The molecule and how long it lasts

Identity
Formula
C45H55N9O6
Molecular weight
818.0 g/mol
CAS number
158861-67-7
PubChem
CID 6918245

PubChem record, read 23 September 2026.

Pharmacokinetics
Route
Intravenous (diagnostic use in Japan as pralmorelin)
Half-life
Human intravenous use is documented; no primary half-life figure was found

From a published human pharmacokinetic study: Pralmorelin. Drugs R D 2004;5:236–239

Regulatory status

European Union
Not authorised

No EMA authorisation. Supplying it for human use is an offence under national medicines law.

United States
Not approved

Not an FDA-approved drug; sold as a research chemical. The FDA has flagged GHRPs among peptides that should not be in compounded products.

United Kingdom
Unlicensed medicine

No MHRA licence; supply for human use is an offence.

Australia
Prescription-only / unapproved

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

Japan
Approved (diagnostic)

Pralmorelin (GHRP Kaken) is approved as a diagnostic agent for growth-hormone secretion — not as a treatment.

Sport (WADA)
Prohibited at all times

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

Questions people actually ask

Is GHRP-2 approved?
Only in Japan, and only as a diagnostic test (pralmorelin) for growth-hormone deficiency — a single injection to measure pituitary function. It is not approved anywhere as a treatment for muscle, fat or ageing.
Does it build muscle?
No trial has tested that. It reliably raises growth hormone acutely, but no controlled study has shown that repeated use changes body composition.
Why does it make you hungry?
It mimics ghrelin, the hunger hormone, at the same receptor — so it drives appetite as well as growth-hormone release.

One page per claimed effect

References

  1. 1
    Chihara K, et al. A simple diagnostic test using GH-releasing peptide-2 in adult GH deficiency.Eur J Endocrinol, 2007;157:19–2777 healthy + 58 GH-deficient adults; the diagnostic basis.
  2. 2

Change log

  • 2026-09-03Initial publication. Grade A for the diagnostic GH response, D for the marketed physique use.