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GHRP-6

GHRP-6 is a synthetic six-amino-acid peptide, described in 1984, that stimulates growth hormone release through what is now known as the ghrelin receptor. It is historically important because research on it and similar compounds helped lead to the discovery of that receptor and of ghrelin itself. Human studies are short hormone-response experiments; it has never been approved as a medicine.

By the PepFinder editorial team · Reviewed 23 Sept 2026 · Editorial independence

GHRP-6 suppliers and prices

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35 suppliers in our directory list GHRP-6. Median price per mg: US$3.90 (10 suppliers pricing in USD), £1.90 (11 suppliers pricing in GBP), CA$5.50 (3 suppliers pricing in CAD), A$8.00 (2 suppliers pricing in AUD). Prices are compared only within the same currency.

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What it is

GHRP-6 (growth hormone-releasing peptide 6) has the sequence His-D-Trp-Ala-Trp-D-Phe-Lys-NH2. Cyril Bowers and Frank Momany reported in 1984 that this small synthetic peptide released GH specifically, without releasing LH, FSH, TSH or prolactin in their experiments, and that it worked in rats, monkeys, lambs and calves. When injected once or twice daily into young rats for 9 to 25 days, it increased weight gain, and the pituitary was still fully responsive to it at the end [1].

Its mechanism was unknown for years. In 1996 researchers cloned the receptor that GHRP-6 and related compounds act on, the growth hormone secretagogue receptor [2], and in 1999 its natural ligand was identified as ghrelin, a hormone made in the stomach [3]. GHRP-6 is therefore the parent of a family that includes GHRP-2, hexarelin and ipamorelin.

How it is thought to work

GHRP-6 mimics ghrelin at the GHS-R1a receptor in the pituitary and hypothalamus, triggering a pulse of GH. In healthy men, intravenous GHRP-6 raised GH in a dose-dependent way, and combining it with GHRH released more GH than the two would be expected to release separately. The authors took this synergy as evidence that GHRPs work through a system separate from GHRH [4]. It underlies the common practice of pairing a GHRP with a GHRH analogue such as CJC-1295 or sermorelin, though those specific combinations have not been tested in published trials.

Unlike ipamorelin, GHRP-6 is not fully selective for GH. At the highest intravenous dose in the 1990 study, prolactin and cortisol each rose about twofold [4], and in pigs GHRP-6 raised ACTH and cortisol where ipamorelin did not [5]. As a ghrelin mimetic it is also widely described as increasing appetite; this has been shown in people for GHRP-2 [6] but we did not find an equivalent controlled human study for GHRP-6.

What the research shows

In humans the published work measures hormones rather than clinical outcomes. Intravenous doses of 0.1, 0.3 and 1.0 µg/kg produced mean peak GH levels of 7.6, 16.5 and 68.7 µg/L in 18 healthy men [4]. Taken by mouth, GHRP-6 still released GH at doses of 100 and 300 µg/kg, but with only about 0.3% of the intravenous activity; in nine children with short stature and varying degrees of GH deficiency, four responded like adults and the rest had low or undetectable responses [7].

A 2013 Cuban phase 1 study measured GHRP-6 levels in nine healthy men after single intravenous doses of 100, 200 and 400 µg/kg. The elimination half-life was about 2.5 hours, and the amount in the blood rose roughly in proportion to dose. The authors also noted unexplained spikes in GHRP-6 concentration during the elimination phase in four of the nine volunteers [8].

Animal research has explored effects beyond GH. In adult female rats, 12 weeks of GHRP-6 or ipamorelin increased bone mineral content by making bones larger, not denser [9]. A Cuban group has studied GHRP-6 as a tissue-protective agent: in pigs with an induced heart attack, a single 400 µg/kg dose reduced infarct mass by 78% compared with saline, which the authors linked to antioxidant effects [10]. These findings have not been tested in human trials.

Doses used in published research

Human studies used single intravenous doses of 0.1 to 1.0 µg/kg [4], oral doses of 100 and 300 µg/kg [7], and, in the pharmacokinetic study, intravenous doses of 100 to 400 µg/kg [8]. Animal studies used 0.5 mg/kg per day by infusion in rats [9] and 400 µg/kg in pigs [10]. These figures describe what researchers gave; they are not recommendations, and animal doses should not be converted into human ones. For reconstitution arithmetic, see our peptide calculator.

Safety and side effects reported

In the 1990 dose-ranging study, no adverse clinical effects or laboratory abnormalities were seen after GHRP-6 injection; the brief facial flushing reported was after GHRH, not GHRP-6 [4]. The known effects are hormonal: rises in prolactin and cortisol at higher doses [4][5]. There are no long-term human safety data, and products sold for research are not manufactured to medicine standards.

Regulatory status

GHRP-6 is not an approved medicine in the UK, US, Canada, Australia or New Zealand. It appears by name on the WADA Prohibited List among the GH-releasing peptides in section S2 and is banned at all times [11]. Anti-doping laboratories have found glycine-extended GHRP-6 in black-market products [12]. For national rules, see our legal status overview.

Storage and handling

GHRP-6 for research is sold as a freeze-dried powder, and no stability data have been published for these products. See our guides to storing peptides and bacteriostatic water.

Buying and testing

Compare prices per milligram, check the certificate of analysis with our guide on how to read a COA, and prefer third-party tested suppliers.

References

  1. [1] Bowers CY, Momany FA, Reynolds GA, Hong A On the in vitro and in vivo activity of a new synthetic hexapeptide that acts on the pituitary to specifically release growth hormone Endocrinology. 1984. PubMed 6714155
  2. [2] Howard AD, Feighner SD, Cully DF, Arena JP, et al. A receptor in pituitary and hypothalamus that functions in growth hormone release Science. 1996. PubMed 8688086
  3. [3] Kojima M, Hosoda H, Date Y, Nakazato M, et al. Ghrelin is a growth-hormone-releasing acylated peptide from stomach Nature. 1999. PubMed 10604470
  4. [4] Bowers CY, Reynolds GA, Durham D, Barrera CM, et al. Growth hormone (GH)-releasing peptide stimulates GH release in normal men and acts synergistically with GH-releasing hormone J Clin Endocrinol Metab. 1990. PubMed 2108187
  5. [5] Raun K, Hansen BS, Johansen NL, Thøgersen H, et al. Ipamorelin, the first selective growth hormone secretagogue Eur J Endocrinol. 1998. PubMed 9849822
  6. [6] Laferrère B, Abraham C, Russell CD, Bowers CY Growth hormone releasing peptide-2 (GHRP-2), like ghrelin, increases food intake in healthy men J Clin Endocrinol Metab. 2005. PubMed 15699539
  7. [7] Bowers CY, Alster DK, Frentz JM The growth hormone-releasing activity of a synthetic hexapeptide in normal men and short statured children after oral administration J Clin Endocrinol Metab. 1992. PubMed 1730807
  8. [8] Cabrales A, Gil J, Fernández E, Valenzuela C, et al. Pharmacokinetic study of growth hormone-releasing peptide 6 (GHRP-6) in nine male healthy volunteers Eur J Pharm Sci. 2013. PubMed 23099431
  9. [9] Svensson J, Lall S, Dickson SL, Bengtsson BA, et al. The GH secretagogues ipamorelin and GH-releasing peptide-6 increase bone mineral content in adult female rats J Endocrinol. 2000. PubMed 10828840
  10. [10] Berlanga J, Cibrian D, Guevara L, Dominguez H, et al. Growth-hormone-releasing peptide 6 (GHRP6) prevents oxidant cytotoxicity and reduces myocardial necrosis in a model of acute myocardial infarction Clin Sci (Lond). 2007. PubMed 16989643
  11. [11] World Anti-Doping Agency The Prohibited List (2026): S2.2.4 Growth hormone releasing factors wada-ama.org. 2026. Source
  12. [12] Krug O, Thomas A, Malerød-Fjeld H, Dehnes Y, et al. Analysis of new growth promoting black market products Growth Horm IGF Res. 2018. PubMed 29864719

Frequently asked questions

What is GHRP-6?

GHRP-6 is a synthetic six-amino-acid peptide that stimulates growth hormone release by acting on the ghrelin receptor. It was first described in 1984, before the receptor it acts on had been identified.

Does GHRP-6 increase appetite?

GHRP-6 is a ghrelin mimetic and is widely reported to increase hunger, and the closely related GHRP-2 increased food intake by about 36% in a controlled study in men. We did not find an equivalent controlled human study of GHRP-6 itself.

What is the difference between GHRP-6 and ipamorelin?

Both act on the ghrelin receptor, but in animal studies ipamorelin released GH without raising ACTH or cortisol, whereas GHRP-6 raised both. GHRP-6 also raised prolactin and cortisol at higher doses in men.

What is the half-life of GHRP-6?

In a study of nine healthy men given intravenous GHRP-6, the elimination half-life averaged about 2.5 hours.

Is GHRP-6 banned in sport?

Yes. GHRP-6 is named on the WADA Prohibited List among the GH-releasing peptides and is banned at all times.

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