GHRP-6

Growth hormone releasing peptide-6, GHRP, SKF-110679, His-D-Trp-Ala-Trp-D-Phe-Lys-NH2

Growth hormone axis

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Summary

Class: Synthetic hexapeptide (6 amino acids) growth hormone secretagogue; ghrelin receptor (GHS-R1a) agonist
Mechanism: Activates the ghrelin receptor in the pituitary and hypothalamus, releasing a pulse of growth hormone; also raises appetite, cortisol and prolactin
Routes studied: Intravenous, subcutaneous, intranasal and oral (human pharmacology studies); subcutaneous (community)
Dose range reported: Human studies: ~1 µg/kg IV as a single dose; subcutaneous and intranasal doses several-fold higher; oral doses in the hundreds of µg/kg. Community: 100–300 µg subcutaneous, 1–3 times daily, often with a GHRH analogue. No approved human dose
Half-life: Short. GH peaks within 15–30 minutes of an IV dose and returns toward baseline within about 2 hours; plasma half-life of the peptide itself is not well defined in humans †
Storage: Lyophilised: refrigerate, protect from light. Reconstituted: refrigerate, use within ~4 weeks (community practice)
Regulatory status: Not approved for any indication anywhere

Doses are as reported in studies or by the community — never recommendations.

1What it is

GHRP-6 is the original growth hormone releasing peptide. It was designed in the early 1980s by Cyril Bowers and Frank Momany, who started from met-enkephalin (an opioid peptide) and modified it until it released growth hormone (GH) from pituitary cells without any opioid activity. It is entirely synthetic; nothing with this sequence exists in the body.

Its scientific importance is larger than its clinical record. Researchers trying to work out how GHRP-6 released GH found a previously unknown receptor in 1996 (the growth hormone receptor, ), and three years later the natural hormone that binds it, ghrelin, was discovered in the stomach. In other words, GHRP-6 is the compound that led to the discovery of the hunger hormone. GHRP-6 itself was never developed into a medicine; later, more selective compounds (GHRP-2, hexarelin, ipamorelin, and the oral drug MK-677) followed from it.

In the community it is used as a GH secretagogue and, because it strongly increases appetite, sometimes specifically for that effect.

2How it's thought to work

Pituitary. binds on somatotroph cells and triggers GH release through a different intracellular pathway from GHRH, which is why the two act synergistically when given together.

Hypothalamus. appears to increase GHRH release and reduce somatostatin tone, amplifying the pulse.

Appetite. GHS-R1a is the ghrelin receptor, so GHRP-6 mimics ghrelin's hunger signal. Users typically notice this within 20–30 minutes.

Other hormones. unlike ipamorelin, GHRP-6 also raises ACTH/cortisol and prolactin modestly at GH-releasing doses.

Non-pituitary actions. GHS-R1a and the scavenger receptor CD36 are expressed in heart and other tissues; a Cuban research group has reported cytoprotective effects in animals that appear independent of GH.

Activates the ghrelin receptor in the pituitary and hypothalamus: a pulse of growth hormone and a strong rise in appetite.Schematic — not to scale

3What the research shows

GH release in humans

Multiple small studies in healthy adults, children and older adults from the late 1980s onward show that IV GHRP-6 (around 1 µg/kg) produces a GH peak larger than GHRH at equivalent doses, and that GHRP-6 plus GHRH produces a markedly larger, synergistic response (Bowers 1990, J Clin Endocrinol Metab). , intranasal and oral routes were also shown to release GH, with much lower potency orally. These are acute pharmacology studies, not treatment trials. [2]

Graded B/— (limited)

Chronic dosing, body composition, growth

Short courses in GH-deficient children and small studies in adults suggested GH responses persist with repeated dosing, but no controlled trial of GHRP-6 for body composition, strength or recovery in adults exists. Most chronic-dosing data in this class come from GHRP-2 and hexarelin rather than GHRP-6.

Graded D/C

Receptor and ghrelin discovery

Cloning of using GHRP-6 and MK-677 as ligands (Howard 1996, Science); identification of ghrelin as the endogenous ligand (Kojima 1999, Nature). [3][4]

Cardioprotection and organ protection

Rat and pig studies from a Cuban group report reduced infarct size and oxidative damage after GHRP-6 in acute myocardial infarction and multiple-organ-failure models (Cibrián 2006, Clin Sci; Berlanga 2007, Clin Sci). Not studied in humans. [5][6]

Appetite stimulation

GH reliably increase food intake in humans; the clearest controlled data are for the sister compound GHRP-2 (Laferrère 2005, J Clin Endocrinol Metab). Community reports for GHRP-6 are consistent with a pronounced hunger effect. [7]

4Reported side effects and interactions

Literature-reported

Acute studies report facial flushing, transient warmth, sleepiness and hunger. Cortisol and prolactin rise modestly and briefly after each dose. Blood glucose can rise after GH release. Long-term human safety has not been studied.

Community-reported

strong hunger shortly after injection (the defining feature), water retention, tingling or numbness in hands, lethargy after dosing, headache, injection-site redness; occasional reports of raised fasting glucose.

Theoretical. sustained GH/IGF-1 elevation and reduced insulin sensitivity with chronic use; concern for anyone with active malignancy; repeated cortisol and prolactin stimulation with frequent dosing; receptor desensitisation.

Interactions. synergistic GH release with GHRH analogues (CJC-1295, sermorelin, tesamorelin); glucose-lowering medicines may need monitoring; glucocorticoids and high free fatty acids blunt the GH response.

Markers researchers commonly monitor

Marker	Why it's watched
IGF-1	rises with sustained GH release; the main marker of GH-axis effect and of overshoot.
Fasting glucose and HbA1c	GH is counter-regulatory to insulin; a rise signals reduced insulin sensitivity.
Cortisol (morning)	GHRP-6 stimulates ACTH/cortisol acutely; relevant with frequent dosing.
Prolactin	modestly raised by GHRP-6, unlike ipamorelin.
Body weight and waist	appetite stimulation can produce fat gain that offsets any GH effect.
Blood pressure and fluid status	water retention is common early on.

Free for everyone. Safety information is never behind a paywall.

5Reconstitution and handling

Usually supplied in 5 mg vials. with , swirl gently. Often combined with a GHRH analogue in the same syringe; the calculator supports a two-peptide mix.

Open in calculator, pre-loaded →

6Commonly studied alongside

GHRH analogues (CJC-1295 / mod GRF 1-29, sermorelin) — the synergy is the one well-established interaction in humans. Community stacks also include GHRP-2 and ipamorelin.

Informational cross-links. Not stack recommendations.

7Regulatory status by region

Region	Status (checked —)
United States	Not FDA-approved. Placed in Category 2 of FDA's compounding bulk substances list (2023), restricting compounding
European Union	Not authorised
United Kingdom	Not licensed
Australia	Prescription-only (Schedule 4) classification as a GH secretagogue; not an approved product †
South Africa	Not registered with SAHPRA
Sport (WADA)	Prohibited (S2 — peptide hormones, growth factors, related substances and mimetics; GHRPs are named)

8Open questions

Does chronic GHRP-6 at community doses change body composition in adults? No controlled data.
How quickly does the GH response desensitise with repeated dosing?
Whether the animal cardioprotective findings mean anything for humans.

9References

1Bowers CY, Momany FA, Reynolds GA, Hong A (1984). On the in vitro and in vivo activity of a new synthetic hexapeptide that acts on the pituitary to specifically release growth hormone. Endocrinology. PubMed · DOI
2Bowers CY et al. (1990). Growth hormone (GH)-releasing peptide stimulates GH release in normal men and acts synergistically with GH-releasing hormone. J Clin Endocrinol Metab. PubMed · DOI
3Howard AD et al. (1996). A receptor in pituitary and hypothalamus that functions in growth hormone release. Science. PubMed · DOI
4Kojima M et al. (1999). Ghrelin is a growth-hormone-releasing acylated peptide from stomach. Nature. PubMed · DOI
5Cibrián D et al. (2006). Use of growth-hormone-releasing peptide-6 (GHRP-6) for the prevention of multiple organ failure. Clin Sci (Lond). PubMed · DOI
6Berlanga J et al. (2007). Growth-hormone-releasing peptide 6 (GHRP6) prevents oxidant cytotoxicity and reduces myocardial necrosis in a model of acute myocardial infarction. Clin Sci (Lond). PubMed · DOI
7Laferrère B et al. (2005). Growth hormone releasing peptide-2 (GHRP-2), like ghrelin, increases food intake in healthy men. J Clin Endocrinol Metab. PubMed · DOI
8FDA (2023). Bulk drug substances for compounding — GHRP-6 category 2 listing. PubMed

References are being resolved to PubMed/DOI identifiers; links search PubMed for the citation until then.

† Being confirmed by our reviewers against current sources.

10Community

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Self-reported side effects Phase 2

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11Page history

25 Oct 2026Profile published — awaiting medical review

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