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Evidence-rated reference Updated August 2026
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GHRP-2 vs GHRP-6

These are not equivalent in evidence GHRP-2 is rated 3/5 and GHRP-6 is rated 2/5 — a gap of 1 level on our scale. Similar marketing does not mean similar proof.

GHRP-2 Limited ApprovalGHRP-6 Research Use Only
Evidence rating
3/5 Moderate Evidence rating 3 out of 5: Moderate
2/5 Limited Evidence rating 2 out of 5: Limited
Regulatory statusApproved in Japan as a diagnostic agent for GH deficiency. Not approved in the US or EU for therapeutic use.Not approved. Superseded by more selective secretagogues; largely of historical and research interest.
CategoryGrowth Hormone AxisGrowth Hormone Axis
Drug classGrowth hormone-releasing peptide — synthetic hexapeptide ghrelin mimeticFirst-generation growth hormone-releasing hexapeptide
RouteSubcutaneous or intravenousSubcutaneous (research)
Half-life~33 min (t1/2 0.55 h) after IV — measured in children, the only published human study; no adult figure exists.~2.5 h elimination after IV in healthy men; the short figures quoted elsewhere are its ~8 min distribution phase.
Sequence length6 residues6 residues
Molecular weight818 Da873 Da
Studied inDiagnostic validation studies in Japan; short-term GH secretion studies; small studies in cachexia.Extensive endocrine pharmacology research; small cardioprotection studies; no completed therapeutic development program.
Who should avoid it
  • Active malignancy
  • Pregnancy
  • Hyperprolactinemia
  • Cushing syndrome or adrenal disorder
  • Active malignancy
  • Pregnancy
  • Hyperprolactinemia
  • Diabetes
Legal statusDiagnostic approval in Japan only. Not lawful for therapeutic sale in the US.Not approved for human use in any major market.

Benefits — GHRP-2

  • Strong, reliable GH release

    Robust and reproducible enough to serve as an approved diagnostic stimulus for pituitary function.

  • Appetite stimulation

    Meaningful in cachexia and appetite-loss settings, where it has been studied in small trials.

  • Oral and intranasal bioavailability studied

    Alternative routes have been explored, unlike most peptides.

Benefits — GHRP-6

  • Powerful appetite stimulation

    Among the strongest orexigenic effects of any peptide — potentially useful in cachexia, and unwanted in almost every other context.

  • Reliable GH release

    Effective as a pituitary stimulus, historically important for characterising the GH axis.

  • Preclinical cytoprotective signals

    Animal work suggests cardioprotective and gastric-protective effects.

Risks & cons — GHRP-2

  • Cortisol and prolactin elevation

    Less selective than ipamorelin; repeated dosing can push these hormones outside normal ranges.

  • No therapeutic approval

    Approved only as a one-off diagnostic; chronic dosing has never been evaluated for safety.

  • Tachyphylaxis

    GH response declines with continued use.

  • Insulin resistance

    GH-axis class effect.

  • Unregulated supply outside Japan

    Sold as a research chemical with no quality assurance.

Risks & cons — GHRP-6

  • Intense hunger

    Often sabotages the body-composition goals people take it for.

  • Cortisol and prolactin elevation

    More pronounced than with newer secretagogues; chronic elevation carries real endocrine consequences.

  • No approved use anywhere

    Never completed clinical development.

  • Rapid desensitisation

    Response falls off with repeated dosing.

  • Unregulated supply

    Research-chemical market only.

Infographic for GHRP-2
Infographic for GHRP-6

A comparison is not a recommendation. Neither column is being suggested for you. Which — if either — is appropriate depends on your diagnosis, history and medications, and that is a conversation for a qualified clinician.