COMPOUND

Compounds / GH secretagogues

GHRP-6

Growth Hormone Releasing Peptide-6 (His-D-Trp-Ala-Trp-D-Phe-Lys-NH2)

GH secretagogues SubQ Not FDA approved

The original synthetic GHRP, discovered by Cyril Bowers in 1984 as the first peptide to specifically and dose-dependently release GH in vitro and in vivo. Hexapeptide ghrelin-receptor (GHSR-1a) agonist. Notorious for the most pronounced appetite stimulation of any GHRP: intense hunger 15-20 minutes post-injection.

At a glance

Half-life
~18 min ~15-20 min plasma t½. Peak GH ~15-30 min post-dose; pulse decays over ~2h. Oral bioavailability ~0.30%.
Routes
SubQ
Vial sizes
2 mg · 5 mg · 10 mg
Evidence base
4 studies 2 human · 1 review · 1 preclinical

Mechanism

Binds GHSR-1a on pituitary somatotrophs → cAMP-independent phosphatidylinositol turnover → GH release. Also binds the same receptor on hypothalamic NPY/AgRP neurons in arcuate nucleus, mimicking ghrelin's orexigenic effect. Dose-dependent GH release in humans: peak GH 1.2/7.6/16.5/68.7 mcg/L at placebo/0.1/0.3/1.0 mcg/kg. Above ~1 mcg/kg threshold, additionally stimulates ACTH (cortisol) and prolactin via hypothalamic AVP release: larger spike than GHRP-2 or ipamorelin. Synergizes with GHRH analogs (CJC-1295, sermorelin): true synergy demonstrated, basis for GHRH+GHRP stacking. Oral bioavailability 0.30%, t½ 0.30h.

Dosing

Any amounts shown here are reported from published studies only. 2 of 4 catalogued studies involved human subjects. COMPOUND does not publish its own dosing guidance.

Where a study reports an amount, it appears in that study's entry below, attributed to the source.

Published evidence

  1. Human RCT 1999

    GHRP-6 stimulates ACTH/cortisol release

    Korbonits M, Kaltsas G, Perry LA, et al. J Clin Endocrinol Metab

    Above ~1 mcg/kg, GHRP-6 stimulates ACTH and cortisol via hypothalamic AVP release. Larger spike than GHRP-2 or ipamorelin.

    PMID 10404825

  2. Human RCT 1990

    GHRP stimulates GH release in normal men and acts synergistically with GH-releasing hormone

    Bowers CY, Reynolds GA, Durham D, et al. J Clin Endocrinol Metab

    Dose-dependent GH release in 18 normal men: peak GH 1.2 / 7.6 / 16.5 / 68.7 mcg/L at placebo / 0.1 / 0.3 / 1.0 mcg/kg. Submaximal GHRP-6 + GHRH demonstrated true synergy: basis for GHRH+GHRP stacking.

    PMID 2108187

  3. Review 2018

    The Safety and Efficacy of Growth Hormone Secretagogues

    Sigalos JT, Pastuszak AW Sex Med Rev

    Comprehensive safety/efficacy review. Reports GHRP-6 oral bioavailability 0.30%, t½ 0.30h. Reviews hormonal side effects and glycemic risks of chronic GH-elevating protocols.

    PMID 28400207

  4. Animal in vivo 1984

    On the in vitro and in vivo activity of a new synthetic hexapeptide that acts on the pituitary to specifically release growth hormone

    Bowers CY, Momany FA, Reynolds GA, Hong A Endocrinology

    Foundational paper introducing GHRP-6. First synthetic peptide to specifically and dose-dependently release GH both in vitro and in vivo. Established structure-activity baseline for the entire GHRP class.

    PMID 6714155

Reported side effects

Intense hunger / appetite increase
Very common Moderate · Defining side effect: most pronounced of any GHRP. Onset 15-20 min, lasts 30-60 min. Useful in cachexia/bulking; problematic for fat-loss goals.
Cortisol elevation
Common Moderate · Above ~1 mcg/kg threshold, ACTH and cortisol rise via hypothalamic AVP release. Larger spike than GHRP-2 or ipamorelin. Chronic use measurably elevates baseline.
Prolactin elevation
Common Mild · Stimulates lactotroph secretion. Larger than ipamorelin/GHRP-2.
Flushing / warmth
Occasional Mild · Transient, within minutes of injection.
Water retention
Occasional Mild · GH-mediated; mild compared to MK-677 or CJC-DAC.
Lightheadedness / drowsiness
Occasional Mild · Especially with first doses or dose changes.
Increased fasting glucose / reduced insulin sensitivity
Occasional Moderate · GH-mediated; less prominent than chronic GHRH (CJC-DAC) but worth tracking.

Interactions

  • CJC-1295 (no DAC) Synergy

    GHRH+GHRP supra-additive GH pulse via independent receptor pathways (cAMP vs PI turnover).

  • Ipamorelin Redundant

    Both are GHSR-1a agonists.

  • GHRP-2 Redundant

    Both GHSR-1a agonists; same receptor.

  • Hexarelin Redundant

    Both GHSR-1a agonists; both spike cortisol/prolactin.

  • MK-677 Redundant

    Both target GHSR-1a; oral and injectable ghrelin mimetics overlap.

  • Food Absorption interference

    Insulin and somatostatin surges from food blunt GH pulse.

Reconstitution and storage

5 mg vial + 2 mL BAC water = 2.5 mg/mL = 250 mcg per 10 units on insulin syringe. Gentle swirl, do not shake.

Lyophilized: freezer (-20°C). Reconstituted: refrigerate 2-8°C, use within 30-45 days. Protect from light.

Open the reconstitution calculator for GHRP-6