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PeptideLimited humanNot FDA approved

GHRP-6

Growth Hormone Releasing Peptide 6

Last reviewed October 27, 2026 · 20 sources · Written for general readers · Compare with another compound →

The bottom line

GHRP-6 is one of the first lab made peptides shown to release growth hormone, and in people it was studied mostly as a one time test of the pituitary. Claims about muscle, healing and heart protection rest on animal studies. It was never approved, FDA lists safety concerns including effects on cortisol and blood sugar, and it is banned in sport.

Where the evidence stands

What it is

GHRP-6 is a small lab made peptide of six amino acids, a hexapeptide, in the growth hormone releasing peptide (GHRP) family. It was the first hexapeptide of this kind to be studied widely in people.[1]

A six amino acid peptide of this type was first described in 1984, after tests showed it released growth hormone in rats, monkeys, lambs and calves.[2] Its chemical formula in PubChem is C46H56N12O6.[3]

A Cuban research center has developed a GHRP-6 product called CIGB-500, meant to protect the heart after a heart attack, and has published animal safety testing for it.[4] Among GHRPs, only GHRP-2 has reached clinical approval anywhere, while others circulate on the black market.[5]

Name
GHRP-6 (Growth Hormone Releasing Peptide 6)
Other names
growth hormone releasing hexapeptide, CIGB-500 (Cuban research product)
Type
Peptide
Formula
C46H56N12O6
Molecular weight
About 873 g/mol

How it works

GHRP-6 signals the pituitary gland to release growth hormone through a receptor that is separate from the one used by the body's growth hormone releasing hormone (GHRH).[1] That receptor's natural partner, the hunger hormone ghrelin, was identified in 1999.[6]

  • In cells taken from human pituitary tumors, GHRP-6 switched on an internal signaling pathway, and growth hormone release rose along with it.[7]
  • In guinea pigs, GHRP-6 given into the brain released far more growth hormone than the same peptide given into a vein, which points to the hypothalamus (a control area of the brain) as a main target.[8]
  • Combined with GHRH, it produces a much larger growth hormone release than either alone, even in people with obesity, who normally release little growth hormone.[9]
  • In people it also raises ACTH and cortisol, hormones of the body's stress system.[10]
  • Given by vein, it leaves the blood quickly at first and is mostly cleared within hours.[11]

The hormone release effect is well documented. Benefits beyond that have not been shown in good human trials.

What the research shows

We keep animal and human evidence apart. A result in animals is a reason to study something in people, not proof that it works in people.

Animal and lab studies

Hormone effects and organ protection in animals

  • The 1984 hexapeptide released growth hormone without releasing other pituitary hormones, and repeated injections increased weight gain in young rats.[2]
  • Guinea pig work suggested the brain is a key site of action.[8]
  • In pigs with a lab induced heart attack, GHRP-6 reduced dead heart tissue by 78 percent and its thickness by 50 percent, and seemed to lower oxidative stress.[14]
  • In rats with heart failure, three weeks of shots of GHRP-6 or related peptides improved heart pumping and reduced body wasting.[16]
  • A 2025 mouse study packed GHRP-6 into a gel and reported that it helped kidney cells survive an injury caused by cut off blood flow.[15]
  • In a 28 day safety study in beagle dogs given repeated IV doses of the Cuban GHRP-6 product, higher amounts caused drooling, low activity, a slower heart rate and redness of the head, which the authors judged temporary.[4]

Limit: These animal results, including the heart and kidney work, have not been confirmed in human trials.

Human studies

Small one time test studies only

  • Researchers gave GHRP-6 by vein to children and adults as a test for growth hormone deficiency. Deficient patients responded less, but their results overlapped a lot with healthy people, and patients with a damaged pituitary stalk showed almost no response.[12]
  • In 19 people with obesity, an IV dose released about twice as much growth hormone as GHRH, and combining the two produced a very large release, showing the pituitary in obesity can still respond.[9]
  • In 10 older men, 9 severely obese men and 7 healthy men given GHRP-6 plus GHRH by vein, obese men released much less growth hormone, so the usual test cut off point does not work for them.[17]
  • In a placebo controlled sleep study of healthy men, repeated IV doses during the night raised growth hormone about threefold, raised ACTH and roughly doubled cortisol, and added about 25 minutes of light sleep without changing deep sleep.[10]
  • In 9 healthy men given a single IV dose in a Cuban phase 1 study, GHRP-6 left the blood quickly at first, with most of it cleared within hours. Four of the 9 showed unusual spikes in blood levels later on. The summary did not report side effects.[11]
  • Reviews of this drug class find few long term, well controlled studies of benefits or safety.[13]

Limit: No human trial has tested GHRP-6 as a repeated treatment for any health outcome.

Claims check

The most common claims about this compound, and what studies actually found. Verdicts rate the evidence, not whether you should use it.

Raises growth hormone

Shown in people

In 19 people with obesity, an IV dose of GHRP-6 released about twice as much growth hormone as GHRH, and the two together caused a very large release.[9] In children and adults tested for growth hormone deficiency, deficient patients responded less, but results overlapped with healthy people.[12] These were one time tests, not treatment.

Improves sleep

Mixed results

In a placebo controlled study of healthy men, repeated IV doses during the night raised light stage 2 sleep from about 245 to 270 minutes, but deep sleep did not change. Cortisol in the first part of the night roughly doubled.[10] This is one small study.

Builds muscle and speeds growth

Only in animals

In the first 1984 studies, repeated shots increased weight gain in young rats.[2] No study has measured muscle or strength gain in people given GHRP-6.[13]

Protects the heart

Only in animals

In pigs given a heart attack in the lab, GHRP-6 reduced the mass of dead heart tissue by 78 percent compared with saline, and blood markers of heart damage were lower.[14] No human trial results have been published.

Heals organs and tissues

Only in animals

A 2025 mouse study packed GHRP-6 into a gel and reported that it helped kidney cells survive injury from cut off blood flow.[15] In rats with heart failure, GHRP-6 and related peptides improved heart pumping and reduced body wasting.[16] None of this has been tested in people.

Known risks and side effects

  • Cortisol and blood sugar. In healthy men, GHRP-6 roughly doubled cortisol during the night.[10] FDA says available data raise concerns about effects on cortisol and about higher blood sugar from reduced insulin sensitivity.[18]
  • Limited safety data. FDA describes the safety data for GHRP-6 as limited, and reviews call for more long term study of drugs in this class.[18][13]
  • Immune reactions and impurities. FDA warns that GHRP-6 may trigger immune reactions for certain routes because the peptide can clump and carry impurities.[18]
  • Unregulated products. GHRPs are sold on the black market, and seized vials have held unknown look alike peptides, so labels cannot be trusted.[5]
  • Banned in sport. WADA lists GHRP-6 as a prohibited growth hormone releasing peptide.[19]

Regulatory status

Today: GHRP-6 is not an approved drug. FDA places it in Category 2 for 503B outsourcing facilities because of safety concerns, and in Category 3 for 503A pharmacies.[18][20] WADA bans it.[19]

  1. FDA placed GHRP-6 in Category 2 for 503B outsourcing facilities.[18]
  2. The 2026 WADA Prohibited List took effect and names GHRP-6.[19]
  3. FDA's updated 503A nomination list shows GHRP-6 in Category 3.[20]

Sources

  1. Ghigo E, Arvat E, Muccioli G, Camanni F. Growth hormone-releasing peptides. Eur J Endocrinol. 1997;136(5):445-460. PMID 9186261
  2. Bowers CY, Momany FA, Reynolds GA, et al. 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;114(5):1537-1545. PMID 6714155
  3. PubChem. Ghrp-6, Compound Summary, CID 4345065. National Library of Medicine. PubChem CID 4345065
  4. Castro J, Shaikh I, Silo S, Hum C, Carrier M, DiFruscia R, et al. Subchronic safety assessment of CIGB-500 in beagle dog after repeated daily dose administration over 28 days. Regul Toxicol Pharmacol. 2025;158:105798. PMID 40024561
  5. Poplawska M, Blazewicz A. Identification of a novel growth hormone releasing peptide (a glycine analogue of GHRP-2) in a seized injection vial. Drug Test Anal. 2019;11(1):162-167. PMID 30051972
  6. Bowers CY. History to the discovery of ghrelin. Methods Enzymol. 2012;514:3-32. PMID 22975043
  7. Lei T, Buchfelder M, Fahlbusch R, Adams EF. Growth hormone releasing peptide (GHRP-6) stimulates phosphatidylinositol (PI) turnover in human pituitary somatotroph cells. J Mol Endocrinol. 1995;14(1):135-138. PMID 7772238
  8. Fairhall KM, Mynett A, Robinson IC. Central effects of growth hormone-releasing hexapeptide (GHRP-6) on growth hormone release are inhibited by central somatostatin action. J Endocrinol. 1995;144(3):555-560. PMID 7738479
  9. Cordido F, Peñalva A, Dieguez C, Casanueva FF. Massive growth hormone (GH) discharge in obese subjects after the combined administration of GH-releasing hormone and GHRP-6: evidence for a marked somatotroph secretory capability in obesity. J Clin Endocrinol Metab. 1993;76(4):819-823. PMID 8473389
  10. Frieboes RM, Murck H, Maier P, Schier T, Holsboer F, Steiger A. Growth hormone-releasing peptide-6 stimulates sleep, growth hormone, ACTH and cortisol release in normal man. Neuroendocrinology. 1995;61(5):584-589. PMID 7617137
  11. Cabrales A, Gil J, Fernández E, Valenzuela C, Hernández F, García I, et al. Pharmacokinetic study of Growth Hormone-Releasing Peptide 6 (GHRP-6) in nine male healthy volunteers. Eur J Pharm Sci. 2013;48(1-2):40-46. PMID 23099431
  12. Pombo M, Leal-Cerro A, Barreiro J, et al. Growth hormone releasing hexapeptide-6 (GHRP-6) test in the diagnosis of GH-deficiency. J Pediatr Endocrinol Metab. 1996;9 Suppl 3:333-338. PMID 8887178
  13. Sigalos JT, Pastuszak AW. The Safety and Efficacy of Growth Hormone Secretagogues. Sex Med Rev. 2018;6(1):45-53. PMID 28400207
  14. Berlanga J, Cibrian D, Guevara L, Dominguez H, Alba JS, Seralena A, 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;112(4):241-250. PMID 16989643
  15. Zhao X, Pan K, Li R, et al. GHRP-6 hydrogel for acute kidney injury therapy via metabolic regulation. J Nanobiotechnology. 2025;24(1):15. PMID 41327290
  16. Xu XB, Pang JJ, Cao JM, Ni C, Xu RK, Peng XZ, et al. GH-releasing peptides improve cardiac dysfunction and cachexia and suppress stress-related hormones and cardiomyocyte apoptosis in rats with heart failure. Am J Physiol Heart Circ Physiol. 2005;289(4):H1643-H1651. PMID 15951341
  17. Haijma SV, van Dam PS, de Vries WR, Maitimu-Smeele I, Dieguez C, Casanueva FF, Koppeschaar HP. The GHRH/GHRP-6 test for the diagnosis of GH deficiency in elderly or severely obese men. Eur J Endocrinol. 2005;152(4):575-580. PMID 15817913
  18. U.S. Food and Drug Administration. Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks. Content current as of April 22, 2026. FDA
  19. World Anti-Doping Agency. World Anti-Doping Code: 2026 Prohibited List, section S2 (peptide hormones, growth factors, related substances and mimetics). In effect January 1, 2026. WADA 2026
  20. U.S. Food and Drug Administration. Bulk Drug Substances Nominated for Use in Compounding Under Section 503A of the Federal Food, Drug, and Cosmetic Act. Updated May 14, 2026. FDA 503A categories
Medical disclaimer

This page is educational information only. It is not medical advice and does not replace care from a licensed medical provider. Do not use this page to decide whether to take any substance. Talk to a licensed medical provider first.

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