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Research information only. Not medical advice. 18+ only. Not FDA-approved for human therapeutic use.

GHRP-6

Also known as: Growth Hormone-Releasing Peptide-6, Growth Hormone-Releasing Hexapeptide-6, His-(D-Trp)-Ala-Trp-(D-Phe)-Lys-NH2, GH-Releasing Hexapeptide-6

Synthetic hexapeptide; Growth Hormone Secretagogue (GHS); GHS-R1a agonist

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What it is

GHRP-6 (His-(D-Trp)-Ala-Trp-(D-Phe)-Lys-NH2; MW=872.44 Da) is a synthetic hexapeptide that stimulates GH secretion by binding to the GH secretagogue receptor (GHS-R), a G protein-coupled receptor expressed predominantly in brain, pituitary gland, and pancreas. Its action involves a dual mechanism at both the hypothalamic and pituitary levels: at the pituitary, it activates the phosphatidylinositol second messenger system, leading to protein kinase C (PKC) activation, intracellular Ca2+ mobilization, and GH secretion; it also induces CREB phosphorylation via a PKCσ-dependent pathway. At the hypothalamic level, studies in patients with hypothalamo-pituitary disconnection demonstrate near-complete blockade of GHRP-6-induced GH release, indicating the hypothalamus is the primary site of action. GHRP-6 acts through mechanisms distinct from GHRH—its GH-releasing effect is dependent on endogenous somatostatinergic tone but is not mediated by changes in hypothalamic somatostatin release. It also upregulates Pit-1 transcription in the anterior pituitary via PKC, MAPK kinase, and PKA pathways. Beyond GH secretion, GHRP-6 exhibits cytoprotective, anti-inflammatory, and tissue-regenerative properties across multiple organs including gut, liver, kidney, lung, and heart—mechanisms proposed to involve mTOR-P70 pathway activation, mitochondrial metabolic reprogramming, fatty acid beta-oxidation upregulation, and antioxidant defense activation. GHRP-6 also binds to melanocortin receptor subtypes MC1 and MC5.

Class: Synthetic hexapeptide; Growth Hormone Secretagogue (GHS); GHS-R1a agonist

What it's studied for

  • GH secretagogue / stimulation of GH secretion Mixed
    • GHRPs, including GHRP-6, release GH in animals and humans through a dual complementary action on the hypothalamus and pituitary via a unique receptor. PMID 9893708 Bowers CY (1998). Growth hormone-releasing peptide (GHRP). Cell Mol Life Sci.
    • GHRP-6 (1 µg/kg IV) exerts a potent stimulatory effect on GH secretion in adults and children; effects are independent of sex and age. PMID 8435889 Peñalva A et al. (1993). Influence of sex, age and adrenergic pathways on the growth hormone response to GHRP-6. Clin Endocrinol.
    • GHRP-6 and GHRH together produce synergistic GH release. Atropine completely prevented GH response to GHRP-6; pyridostigmine increased it. GHRP-6's GH-releasing effect is not mediated by changes in hypothalamic somatostatin tone. PMID 8421084 Peñalva A et al. (1993). Effect of GHRH, atropine, pyridostigmine, or hypoglycemia on GHRP-6-induced GH secretion in man. J Clin Endocrinol Metab.
    • Oral GHRP-6 (300 µg/kg) induced a GH response in short-statured children similar to that of IV GHRH (1 µg/kg). PMID 7581965 Bellone J et al. (1995). GH-releasing effect of oral GHRP-6 in children with short stature. Eur J Endocrinol.
    • Oral GHRP-6 (300 µg/kg) induced GH release in both young and elderly men; arginine (8 g oral) enhanced GHRP-6-induced GH in elderly but not young subjects. PMID 8051337 Ghigo E et al. (1994). Arginine enhances the GH-releasing activity of oral GHRP-6 in elderly but not young subjects. J Endocrinol Invest.
  • Diagnosis of adult GH deficiency (combined GHRH+GHRP-6 test) Human observational
    • Combined GHRH+GHRP-6 test (1 µg/kg each IV) in 125 GH-deficient adults vs. 125 controls: GH cut-off of 15.0 µg/L distinguished healthy from GH-deficient adults. Not confounded by age, sex, or adiposity. Proposed as a safe alternative to insulin tolerance test (ITT). PMID 11030292 Popovic V et al. (2000). GH-releasing hormone and GHRP-6 for diagnostic testing in GH-deficient adults. Lancet.
    • GH peak <7 µg/L for GHRP-6 alone and <13 µg/L for combined GHRP-6+GHRH identified all GH-deficient adults as defined by ITT. Only side effect during GHRP-6 administration was flush symptoms. PMID 11980622 Petersenn S et al. (2002). Diagnosis of GH deficiency in adults by testing with GHRP-6 alone or combined with GHRH. Eur J Endocrinol.
    • GH peak <15.0 µg/L after GHRH+GHRP-6 showed 94.4% sensitivity and 98.8% specificity for GHD diagnosis in multicenter study of 50 hypopituitary patients and 100 controls. PMID 12864804 Popovic V et al. (2003). Effectiveness of arginine+GHRH vs GHRH+GHRP-6 test in diagnosing GH deficiency in adults. Clin Endocrinol.
    • GH cut-off of 15.0 µg/L after GHRH+GHRP-6 cannot be used in severely obese men (7/9 obese men remained below cut-off), but was valid in elderly men. PMID 15817913 Haijma SV et al. (2005). The GHRH/GHRP-6 test for diagnosis of GH deficiency in elderly or severely obese men. Eur J Endocrinol.
  • Cytoprotection / prevention of multiple organ failure (ischemia-reperfusion injury) Animal studies only
    • GHRP-6 (120 µg/kg IP) pre-treatment in rats truncated hepatic and intestinal damage, neutrophilic infiltration, and lipid peroxidation by 50–85% after ischemia/reperfusion. Combination with EGF provided additional benefit. In vitro: 3-fold increase in gut epithelial cell migration. PMID 16417467 Cibrián D et al. (2006). Use of GHRP-6 for the prevention of multiple organ failure. Clin Sci.
  • Cardioprotection / post-infarct ventricular remodeling Animal studies only
    • In a rat permanent coronary ligation model, GHRP-6 (minimum effective dose 0.4 mg/kg determined echocardiographically) attenuated myocardial tissue demise, reduced interstitial fibrosis/scarring, and improved left ventricle physiology. Proteomic analysis indicated upregulation of fatty acid beta-oxidation, apoptosis pr PMID 41901314 Wang L et al. (2026). GHRP-6 ameliorates post-infarct ventricular remodeling and systolic dysfunction. Pharmaceuticals.
  • Acute lung injury and pulmonary fibrosis prevention Animal studies only
    • In LPS- and zymosan/PAF-induced mouse models of lung injury, GHRP-6 reduced neutrophilic alveolitis, attenuated lung compliance failure, improved alveolar-capillary permeability, reduced IL-1β serum levels, and preserved lung parenchymal integrity with meager collagen accumulation over 28 days. PMID 41534456 Wang L et al. (2026). GHRP-6 ameliorates acute lung injury and its subsequent evolvement to interstitial fibrosis. Int Immunopharmacol.
  • Acute kidney injury (AKI) therapy Animal studies only
    • A self-assembling GHRP-6 peptide hydrogel enhanced recovery from AKI in a mouse model by reprogramming TEC metabolism (enriching spermidine, L-glutamine, acetyl-CoA) and activating the mTOR-P70 pathway, improving TEC survival. PMID 41327290 Zhao X et al. (2025). GHRP-6 hydrogel for AKI therapy via metabolic regulation. J Nanobiotechnol.
  • Neuroprotection / stroke therapy (combined with rhEGF) Animal studies only
    • In gerbil global brain ischemia, combined rhEGF+GHRP-6 (100+600 µg/kg IP, respectively) administered up to 4 hours after ischemic insult significantly improved survival, neurological outcome, and reduced infarct volume vs. vehicle. PMID 26311576 Subirós N et al. (2016). Assessment of dose-effect and therapeutic time window of rhEGF and GHRP-6 for stroke therapy. Neurol Res.
  • ACTH/cortisol stimulation testing (Cushing's disease, Addison's disease) Human observational
    • GHRP-6 (2 µg/kg IV) significantly increased ACTH and cortisol in 10 Cushing's disease patients; responses similar to DDAVP. Suggests similar mechanisms at hypothalamic or pituitary level. PMID 12809173 Oliveira JHA et al. (2003). GHRP-6 is able to stimulate cortisol and ACTH release in patients with Cushing's disease. J Endocrinol Invest.
    • GHRP-6 (1 µg/kg IV) elicited significantly higher ACTH responses in Addison's disease patients on glucocorticoid replacement vs. controls; enhanced responsiveness was not maintained after 72h glucocorticoid withdrawal. PMID 12739742 Martins MRA et al. (2003). GHRP-6-induced ACTH release in patients with Addison's disease. J Endocrinol Invest.
  • GH deficiency in Prader-Willi syndrome (diagnostic evaluation) Human observational
    • GH responses to GHRP-6 (1 µg/kg IV) were significantly lower in PWS patients compared to obese controls and short normal children, indicating complex hypothalamo-pituitary dysfunction not solely attributable to obesity. PMID 11407654 Grugni G et al. (2001). Impairment of GH responsiveness to GHRP-6 in Prader-Willi syndrome. J Endocrinol Invest.
  • Immunomodulation in aquaculture (fish studies) Animal studies only
    • Dietary GHRP-6 (500 µg/kg of feed) over 97 days in sea bream maintained stable plasma lactate, triglycerides, and cortisol after immune challenge; increased circulating immunoglobulin levels; upregulated mucosal and adaptive immune gene expression without histological alterations. PMID 40906090 Rodríguez-Viera L et al. (2025). GHRP-6 delivered through aquafeeds modulates endocrine and immune responses in Sparus aurata. Biology.
  • Ghrelin receptor antagonism (using [D-Lys3]-GHRP-6 as antagonist tool) Mixed
    • [D-Lys3]-GHRP-6 (6 mg/kg IV, 7 days) in pigs significantly reduced body weight gain, adipocyte size, and promoted adipose lipolysis, hepatic gluconeogenesis, and fatty acid oxidation by inhibiting ghrelin activity. PMID 37301480 Zhang H et al. (2023). [D-Lys3]-GHRP-6 enhances hepatic fatty acid oxidation and gluconeogenesis in a growing pig model. Peptides.
    • [D-Lys3]GHRP-6 (subcutaneous, 7 days) markedly decreased food intake, body weight, blood glucose, insulin, and leptin in ovariectomized HF-diet mice; increased β-hydroxybutyrate and UCP-1 mRNA. Effect was primarily anorexigenic. PMID 21704671 Maletínská L et al. (2011). [D-Lys3]GHRP-6 markedly improves adiposity and metabolic abnormalities in postmenopausal obesity mouse model. Mol Cell Endocrinol.
    • D-Lys-GHRP-6 (2.0 µg/kg IV bolus or continuous infusion) did not modify spontaneous or ghrelin/hexarelin-stimulated GH, PRL, ACTH, or cortisol in 6 normal volunteers, questioning its effectiveness as a GHS-R1a antagonist in human studies. PMID 17112585 Benso A et al. (2007). D-Lys-GHRP-6 does not modify the endocrine response to acylated ghrelin or hexarelin in humans. Neuropeptides.

Community-reported dosing

RouteDoseFrequency / DurationPopulation / contextSource tier
Intravenous bolus100, 200, and 400 µg/kg body weightSingle dosehumanResearch PMID 23099431
Intravenous bolus2 µg/kgSingle dose (two separate occasions)humanResearch PMID 12809173
Intravenous1 µg/kgSingle dosehumanResearch PMID 12739742
Intravenous1 µg/kgSingle dosehumanResearch PMID 8435889
Intravenous1 µg/kgSingle dosehumanResearch PMID 8421084
Intravenous bolus1 µg/kg (combined with GHRH 1 µg/kg)Single dosehumanResearch PMID 11030292
Intravenous bolus93 µg GHRP-6 (combined with GHRH 100 µg)Single dosehumanResearch PMID 15817913
Intravenous bolus100 µg (combined with GHRH 100 µg)Single dosehumanResearch PMID 14693411
Intravenous1 µg/kgSingle dosehumanResearch PMID 34
Intravenous1 µg/kg (GHRP-6 alone) or combined with GHRH 1 µg/kgSingle dosehumanResearch PMID 10583306
Intravenous90 µgSingle dosehumanResearch PMID 7883854
Intravenous1 µg/kgSingle dosehumanResearch PMID 7593423
Oral300 µg/kgSingle dosehumanResearch PMID 7581965
Oral300 µg/kgSingle dosehumanResearch PMID 8051337
IntranasalNot specified (nasal administration, single dose per compound)Single dose; samples collected for 2 dayshumanResearch PMID 25869809
Intraperitoneal120 µg/kg body weightSingle pre-treatment doseanimalResearch PMID 16417467
Intraperitoneal600 µg/kg (combined with rhEGF 100 µg/kg)Single dose; administered up to 4 hours post-ischemiaanimalResearch PMID 26311576
Not specified in abstractMultiple doses tested (specific mg/kg values not stated in abstract); single administration (acute) or five administrations (chronic scenario)Acute: 24 h; Chronic: 15 days or 28 days post-injuryanimalResearch PMID 41534456
Not specified in abstract0.4 mg/kg (minimum effective dose per echocardiographic parameters)7 days post-surgeryanimalResearch PMID 41901314
Not specified (continuous treatment in dwarf rats)1 mg/kg per 24 h14 days (continuous)animalResearch PMID 46
Intravenous6 mg/kg body weight ([D-Lys3]-GHRP-6)7 daysanimalResearch PMID 37301480
SubcutaneousNot specified (subcutaneous, 7 days) ([D-Lys3]GHRP-6)7 daysanimalResearch PMID 21704671
Intraperitoneal20 nmoles/mouse/day or 200 nmoles/mouse/day ([D-Lys3]-GHRP-6)14 days (experiment 1); 18 days (experiment 2)animalResearch PMID 30390209
Oral (dietary)500 µg/kg of feed (dietary)97 daysanimalResearch PMID 40906090
Intravenous bolus or continuous infusion2.0 µg/kg IV bolus or 2.0 µg/kg/h IV infusion; also 2.0 µg/kg bolus + 4.0 µg/kg/h infusion ([D-Lys-GHRP-6])Single sessionhumanResearch PMID 17112585
subcutaneous injection100 mcg3x daily (upon waking, pre-workout or midday, and pre-sleep)Bodybuilders and fitness-oriented biohackers seeking GH pulse stimulation and muscle growth[S] Claude Sonnet 4.6 — synthesized from aggregate training data
subcutaneous injection200-300 mcg1-2x dailyExperienced bodybuilders seeking stronger GH pulses; users who have plateaued on 100 mcg[S] Claude Sonnet 4.6 — synthesized from aggregate training data
subcutaneous injection100 mcg2x daily (upon waking and pre-sleep)Biohackers and anti-aging community members prioritizing IGF-1 elevation and sleep quality[S] Claude Sonnet 4.6 — synthesized from aggregate training data
subcutaneous injection100 mcg1x daily, 30 minutes pre-workoutFitness-oriented users running a conservative or introductory GHRP protocol[S] Claude Sonnet 4.6 — synthesized from aggregate training data
subcutaneous injection100 mcg3x dailyBodybuilders and physique athletes stacking GHRP-6 with CJC-1295 no DAC (Mod GRF 1-29)[S] Claude Sonnet 4.6 — synthesized from aggregate training data
subcutaneous injection150 mcg3x dailyIntermediate-to-advanced bodybuilders seeking enhanced GH output beyond the standard 100 mcg dose[S] Claude Sonnet 4.6 — synthesized from aggregate training data
subcutaneous injection100 mcg1x daily, pre-sleepOlder adults (40+) and longevity-focused biohackers using GHRP-6 as a conservative GH secretagogue[S] Claude Sonnet 4.6 — synthesized from aggregate training data
subcutaneous injection200 mcg3x dailyAdvanced bodybuilders and experienced peptide users pursuing aggressive GH optimization[S] Claude Sonnet 4.6 — synthesized from aggregate training data
subcutaneous injection100 mcg2x daily (pre-workout and pre-sleep)Intermediate users seeking a balanced protocol with manageable hunger side effects[S] Claude Sonnet 4.6 — synthesized from aggregate training data
intramuscular injection100 mcg3x dailyBodybuilders preferring IM injection for potentially faster absorption kinetics[S] Claude Sonnet 4.6 — synthesized from aggregate training data

Tier key: Research = PMID-cited study · [C] = scraped community source · [S] = model-synthesized from aggregate community reports (softer evidence). How we source.

References

  1. [1] PMID 9893708 — GHRPs, including GHRP-6, release GH in animals and humans through a dual complementary action on the hypothalamus and pituitary via a unique receptor.
  2. [2] PMID 8435889 — GHRP-6 (1 µg/kg IV) exerts a potent stimulatory effect on GH secretion in adults and children; effects are independent of sex and age.
  3. [3] PMID 8421084 — GHRP-6 and GHRH together produce synergistic GH release. Atropine completely prevented GH response to GHRP-6; pyridostigmine increased it. GHRP-6's GH-releasing
  4. [4] PMID 7581965 — Oral GHRP-6 (300 µg/kg) induced a GH response in short-statured children similar to that of IV GHRH (1 µg/kg).
  5. [5] PMID 8051337 — Oral GHRP-6 (300 µg/kg) induced GH release in both young and elderly men; arginine (8 g oral) enhanced GHRP-6-induced GH in elderly but not young subjects.
  6. [6] PMID 11030292 — Combined GHRH+GHRP-6 test (1 µg/kg each IV) in 125 GH-deficient adults vs. 125 controls: GH cut-off of 15.0 µg/L distinguished healthy from GH-deficient adults.
  7. [7] PMID 11980622 — GH peak <7 µg/L for GHRP-6 alone and <13 µg/L for combined GHRP-6+GHRH identified all GH-deficient adults as defined by ITT. Only side effect during GHRP-6 admi
  8. [8] PMID 12864804 — GH peak <15.0 µg/L after GHRH+GHRP-6 showed 94.4% sensitivity and 98.8% specificity for GHD diagnosis in multicenter study of 50 hypopituitary patients and 100
  9. [9] PMID 15817913 — GH cut-off of 15.0 µg/L after GHRH+GHRP-6 cannot be used in severely obese men (7/9 obese men remained below cut-off), but was valid in elderly men.
  10. [10] PMID 16417467 — GHRP-6 (120 µg/kg IP) pre-treatment in rats truncated hepatic and intestinal damage, neutrophilic infiltration, and lipid peroxidation by 50–85% after ischemia/
  11. [11] PMID 41901314 — In a rat permanent coronary ligation model, GHRP-6 (minimum effective dose 0.4 mg/kg determined echocardiographically) attenuated myocardial tissue demise, redu
  12. [12] PMID 41534456 — In LPS- and zymosan/PAF-induced mouse models of lung injury, GHRP-6 reduced neutrophilic alveolitis, attenuated lung compliance failure, improved alveolar-capil
  13. [13] PMID 41327290 — A self-assembling GHRP-6 peptide hydrogel enhanced recovery from AKI in a mouse model by reprogramming TEC metabolism (enriching spermidine, L-glutamine, acetyl
  14. [14] PMID 26311576 — In gerbil global brain ischemia, combined rhEGF+GHRP-6 (100+600 µg/kg IP, respectively) administered up to 4 hours after ischemic insult significantly improved
  15. [15] PMID 12809173 — GHRP-6 (2 µg/kg IV) significantly increased ACTH and cortisol in 10 Cushing's disease patients; responses similar to DDAVP. Suggests similar mechanisms at hypot
  16. [16] PMID 12739742 — GHRP-6 (1 µg/kg IV) elicited significantly higher ACTH responses in Addison's disease patients on glucocorticoid replacement vs. controls; enhanced responsivene
  17. [17] PMID 11407654 — GH responses to GHRP-6 (1 µg/kg IV) were significantly lower in PWS patients compared to obese controls and short normal children, indicating complex hypothalam
  18. [18] PMID 40906090 — Dietary GHRP-6 (500 µg/kg of feed) over 97 days in sea bream maintained stable plasma lactate, triglycerides, and cortisol after immune challenge; increased cir
  19. [19] PMID 37301480 — [D-Lys3]-GHRP-6 (6 mg/kg IV, 7 days) in pigs significantly reduced body weight gain, adipocyte size, and promoted adipose lipolysis, hepatic gluconeogenesis, an
  20. [20] PMID 21704671 — [D-Lys3]GHRP-6 (subcutaneous, 7 days) markedly decreased food intake, body weight, blood glucose, insulin, and leptin in ovariectomized HF-diet mice; increased
  21. [21] PMID 17112585 — D-Lys-GHRP-6 (2.0 µg/kg IV bolus or continuous infusion) did not modify spontaneous or ghrelin/hexarelin-stimulated GH, PRL, ACTH, or cortisol in 6 normal volun
  22. [22] PMID 23099431 — 100, 200, and 400 µg/kg body weight Intravenous bolus (human)
  23. [23] PMID 14693411 — 100 µg (combined with GHRH 100 µg) Intravenous bolus (human)
  24. [24] PMID 34 — 1 µg/kg Intravenous (human)
  25. [25] PMID 10583306 — 1 µg/kg (GHRP-6 alone) or combined with GHRH 1 µg/kg Intravenous (human)
  26. [26] PMID 7883854 — 90 µg Intravenous (human)
  27. [27] PMID 7593423 — 1 µg/kg Intravenous (human)
  28. [28] PMID 25869809 — Not specified (nasal administration, single dose per compound) Intranasal (human)
  29. [29] PMID 46 — 1 mg/kg per 24 h Not specified (continuous treatment in dwarf rats) (animal)
  30. [30] PMID 30390209 — 20 nmoles/mouse/day or 200 nmoles/mouse/day ([D-Lys3]-GHRP-6) Intraperitoneal (animal)
  31. [31] PMID 15814848 — in-prose reference
  32. [32] PMID 7772238 — in-prose reference
  33. [33] PMID 20407870 — in-prose reference
  34. [34] PMID 11518797 — in-prose reference
  35. [35] PMID 9574823 — in-prose reference
  36. [36] PMID 22154075 — in-prose reference
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