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GHRP-6: what the research shows, and what it doesn’t

By Pinnacle Pulse Editorial Team · Status as of 16 October 2026 · Next scheduled update: 14 January 2027

Short answer: GHRP-6 is a synthetic six-amino-acid peptide from the early 1980s that triggers growth hormone release. It helped scientists find the ghrelin receptor. In people it has been studied mainly in Cuba, combined with another growth factor, for acute stroke. A 2026 phase 3 trial missed its main goal. GHRP-6 is not an approved medicine.

What GHRP-6 is

In 1984 Cyril Bowers and three colleagues published a paper in Endocrinology about a six-amino-acid peptide they had made: His-DTrp-Ala-Trp-DPhe-LysNH2. Inject it and the pituitary released growth hormone. It did so in rats, in monkeys, in lambs and in calves. What nobody could say back then was which receptor it acted on.

That took a while. In 1996 a Merck team reported in Science that they had cloned the receptor, which they named the growth hormone secretagogue receptor. Three years later Masayasu Kojima and colleagues found the body’s own hormone for it, a peptide made in the stomach, and named it ghrelin (Nature, 1999). So the synthetic peptide came first, and the natural hormone turned up fifteen years later, partly thanks to it.

GHRP is short for growth hormone-releasing peptide. The 6 is the number of amino acids. Don’t confuse it with GHRH analogs like CJC-1295 or sermorelin: those work through a different receptor. GHRP-6 works through the ghrelin receptor, the same one that makes you hungry.

What has been studied

Early animal work

According to the 1984 paper, GHRP-6 didn’t raise the reproductive hormones, TSH or prolactin, and in a few tests it left insulin and glucagon alone too. Young rats injected daily for 9 or 25 days put on more weight than controls. Later pig experiments, run by a Danish group comparing several of these peptides, found GHRP-6 did push up ACTH and cortisol. That contrast is exactly what the same group later highlighted when it presented ipamorelin.

People: a stroke program in Havana

Almost all recent human work on GHRP-6 comes from a single institution, the Center for Genetic Engineering and Biotechnology in Havana. Researchers there have been testing it, together with epidermal growth factor (EGF), as a way to limit brain damage after a stroke.

First they checked how the body handles it. Nine healthy men got one intravenous dose each in a 2013 study, and the peptide had an elimination half-life of roughly two and a half hours.

The stroke trials followed. A phase I/II study, published in 2024, randomized 36 patients with acute ischemic stroke: 10 to one dose of the GHRP-6 plus EGF combination, 10 to a higher one, 16 to standard care. Nobody was blinded. The main question was safety. Serious adverse events were actually rarer in the two treatment groups, and only two events, both in one patient, were put down to the treatment. The team thought the functional results justified a bigger trial.

They ran it. COURAGE-2, a phase 3 trial in the Journal of Clinical Neuroscience (2026), randomized 188 patients, 95 to the combination, again without blinding. On its primary endpoint, disability at six months, it found no difference from standard care. Survival and daily-living scores didn’t differ either. In 27 patients with the most severe strokes the treated group did better, and the authors want a follow-up trial in that group. Fair enough, but a subgroup of 27, examined after the main result came back negative, is a lead and not a finding. Several of the authors work for the center that develops the product, as the paper discloses.

What the research does not show

The human trials tested GHRP-6 only in combination with epidermal growth factor, intravenously, in hospital, for a week after a stroke. They say nothing about GHRP-6 used on its own, by healthy people, for muscle, fat loss or recovery.

The one large trial was negative on its main question. The positive signal sits in a small subgroup of an open-label study.

There are no long-term safety data in healthy people. FDA’s assessment flags the issues that come with stimulating this receptor: possible immune reactions, a potential effect on cortisol, and higher blood sugar through reduced insulin sensitivity.

And the Cuban program doesn’t tell you what’s in a product sold online, where content and purity are unchecked.

Status as of 16 October 2026. EU and US: not an authorized medicine (no entry in EMA’s medicines data or in Drugs@FDA). FDA has placed GHRP-6 in category 2 of its 503B interim policy (since 29 September 2023), meaning it may present significant safety risks. WADA: the 2027 Prohibited List names GHRP-6 under S2.2.4 (growth hormone-releasing peptides), prohibited at all times.

FAQ

What is the difference between GHRP-6 and ghrelin?

Ghrelin is the body’s own hormone, made mainly in the stomach. GHRP-6 is a synthetic peptide, designed before ghrelin was discovered, that acts on the same receptor.

Has GHRP-6 been tested in humans?

Yes, but mostly in one research program in Cuba that combined it with epidermal growth factor for acute stroke. The phase 3 trial, published in 2026, did not meet its primary endpoint.

Does GHRP-6 raise appetite or blood sugar?

It acts on the ghrelin receptor, which is involved in appetite. FDA’s safety assessment lists a potential effect on cortisol and an increase in blood glucose via decreased insulin sensitivity among its concerns.

Sources

  • Bowers CY, 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):1537-45. PMID 6714155
  • Howard AD, et al. A receptor in pituitary and hypothalamus that functions in growth hormone release. Science. 1996;273(5277):974-7. PMID 8688086
  • Kojima M, et al. Ghrelin is a growth-hormone-releasing acylated peptide from stomach. Nature. 1999;402(6762):656-60. PMID 10604470
  • Raun K, et al. Ipamorelin, the first selective growth hormone secretagogue. Eur J Endocrinol. 1998;139(5):552-61. PMID 9849822
  • Cabrales A, 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):40-6. PMID 23099431
  • Hernández-Bernal F, et al. Combination therapy of epidermal growth factor and growth hormone-releasing hexapeptide in acute ischemic stroke: a phase I/II non-blinded, randomized clinical trial. Front Neurol. 2024;15:1303402. PMID 38638315
  • Hernández-Bernal F, et al. Phase III open-label, randomized clinical trial of epidermal growth factor and growth hormone releasing hexapeptide in acute ischemic stroke. J Clin Neurosci. 2026;152:112195. PMID 42462342
  • FDA. Certain bulk drug substances for use in compounding that may present significant safety risks (content current as of 22 April 2026). fda.gov
  • WADA. 2027 Prohibited List, class S2.2.4. wada-ama.org
  • EMA. Download medicine data: table of all medicines assessed by EMA (Excel), checked 16 October 2026. ema.europa.eu
  • FDA. Drugs@FDA, database of FDA-approved drugs, checked 16 October 2026. accessdata.fda.gov

Facts last checked: 16 October 2026.

About this article

Written by: the Pinnacle Pulse Editorial Team, the people who make the Pinnacle Pulse app. We work only from primary sources such as regulators, legal texts, trial registries and PubMed, and we remove claims we can’t check against one.

This article has not been reviewed by a physician. It is general information, not medical advice.

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Change log

  • 16 October 2026: First published.

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