Peptide Evidence Index

GHRP-6

Evidence last reviewed: September 2026

Quick answers

What is it?: GHRP-6 is a fully synthetic chain of six amino acids, the original member of the GHRP family of growth-hormone-releasing peptides. It is not approved as a medicine and is sold only as an unregulated research chemical.
Why are people interested in it?: It's marketed for muscle building, fat loss, and anti-aging, but it also has an unusually real modern clinical trial program for a completely different use: stroke treatment.
What has actually been studied?: A Cuban research group tested GHRP-6 combined with epidermal growth factor (EGF) as an intravenous stroke therapy, through a 36-patient Phase I/II trial and a 188-patient Phase III trial; separately, a pharmacokinetic study gave single IV doses to nine healthy men.
How strong is the evidence?: Mixed and, on the primary result, negative: the Phase III stroke trial missed its main endpoint, and no human trial has ever tested GHRP-6 alone for the muscle, fat-loss, or anti-aging uses it is marketed for.
What don't we know yet?: Whether a signal of benefit seen only in the most severe stroke patients is real, whether GHRP-6 contributes anything when it isn't combined with EGF, and whether it has any effect on muscle, fat, or aging in healthy adults.
Where can I read the original research?: Sources at the bottom of this page: Combination therapy of Epidermal Growth Factor and Growth Hormone-Releasing Hexapeptide in acute ischemic stroke, Frontiers in Neurology 2024; Phase III trial of EGF and GHRP-6 in acute ischemic stroke (COURAGE-2), Journal of Clinical Neuroscience 2026.

Plain-English overview

GHRP-6 is a fully synthetic six-amino-acid peptide and the original prototype of the GHRP family, the first small peptide shown to mimic the natural hunger hormone ghrelin and trigger a pulse of growth hormone from the pituitary gland. It has never been approved as a medicine for any use and is sold only as an unregulated research chemical, prohibited at all times in competitive sport. Unusually for a compound marketed this way, GHRP-6 has a real, modern clinical trial program behind it: a Cuban research group has tested it intravenously, combined with epidermal growth factor (EGF), as a possible treatment given in the first hours after an acute ischemic stroke. That program progressed from a 36-patient Phase I/II safety trial to a 188-patient Phase III efficacy trial — real drug-development-style human research, just not for the reasons GHRP-6 is sold today. None of that stroke research involved GHRP-6 alone, and none of it touches the muscle-building, fat-loss, or anti-aging claims made about it in the research-chemical market.

What researchers are studying it for

acute ischemic stroke (combined with epidermal growth factor, not alone)
acute growth hormone response (pharmacokinetic measurement only)
appetite and tissue-protective effects (animal studies)

Current evidence level

Mixed human evidence

Regulatory status: Not an approved medicine. Evidence strength and approval are scored separately; approval is a regulatory decision about a specific use, not a measure of how much research exists.

Human research

GHRP-6 has more real human outcome-trial evidence than most compounds in this library, but all of it comes from one Cuban research program testing GHRP-6 combined with epidermal growth factor (EGF) for acute ischemic stroke, not from testing GHRP-6 alone. A Phase I/II trial in 36 patients, published in 2024 in Frontiers in Neurology, gave the combination intravenously within hours of stroke onset and found it safe, with fewer serious adverse events than standard care, and reported encouraging signals on disability and survival at three and six months. That result justified a larger Phase III trial in 188 patients, published in 2026 in the Journal of Clinical Neuroscience under the name COURAGE-2, comparing twice-daily intravenous EGF plus GHRP-6 against standard care for seven days. On the trial's primary, pre-specified intention-to-treat analysis, there was no significant difference between the treated and control groups in disability, daily function, or survival. A secondary analysis restricted to the most severe strokes (NIHSS score of 15 or higher) suggested reduced disability and lower mortality risk in the treated group, but this was not the trial's primary result and the overall trial missed its main endpoint. Separately, an older pharmacokinetic study gave single intravenous doses of GHRP-6 alone — 100, 200, or 400 micrograms per kilogram — to nine healthy men and tracked how it moved through and cleared from the bloodstream over about 12 hours; it measured no health outcome. No trial registered on ClinicalTrials.gov exists for GHRP-6; all the stroke trials are registered in the Cuban Public Registry of Clinical Trials. No human trial has ever tested GHRP-6 alone for muscle growth, fat loss, recovery, or anti-aging, the uses it is most commonly marketed for.

Animal and preclinical research

A preclinical dose-ranging and time-window study in animals examined EGF and GHRP-6 coadministration ahead of the human stroke program, helping establish the dosing and treatment-window assumptions later used in the Phase I/II and Phase III trials. Separately, animal and cell studies have reported GHRP-6 reducing lung and kidney injury in rodents. That work is real but preclinical, and it has not been tested in people for those uses.

Major findings

A Cuban Phase I/II trial in 36 acute ischemic stroke patients found intravenous GHRP-6 combined with epidermal growth factor safe, with fewer serious adverse events than standard care and encouraging disability/survival signals at three and six months (Frontiers in Neurology, 2024).
The follow-up Phase III trial (COURAGE-2), in 188 patients, missed its primary endpoint: no significant difference in disability, daily function, or survival between the treated and control groups on the intention-to-treat analysis (Journal of Clinical Neuroscience, 2026).
A secondary analysis limited to the most severe strokes (NIHSS ≥15) suggested reduced disability and lower mortality risk with treatment, but this was not the trial's pre-specified primary result.
A pharmacokinetic study in nine healthy men measured how single IV doses of GHRP-6 alone (100–400 µg/kg) moved through and cleared from the bloodstream, without measuring any health outcome.
Animal studies have reported GHRP-6 reducing lung and kidney injury in rodents, and preclinical dose-ranging work underpinned the human stroke trial's dosing regimen.
No human trial has ever tested GHRP-6 alone — without EGF — for any purpose, efficacy-related or otherwise.

What has not been established

Whether GHRP-6 contributes anything on its own, since every human efficacy trial tested it combined with epidermal growth factor, never alone.
Whether the severe-stroke subgroup benefit is real or a chance finding, since the trial's primary, whole-population result was negative.
Whether GHRP-6 has any effect on muscle mass, fat loss, or aging in healthy adults — this has never been tested in any human trial.
What repeated, long-term, self-administered use does, since every human trial ran for one week or less.
What is actually in an unregulated vial sold as GHRP-6 online.

Important limitations

The only human outcome trials tested GHRP-6 as part of a two-drug combination with epidermal growth factor, so they cannot isolate what GHRP-6 itself does.
The Phase III trial's positive-looking subgroup finding was a secondary, non-primary analysis in a small subset (27 patients) and needs independent confirmation.
All human efficacy trials were run by one research group in one country (Cuba) and registered in a national registry rather than ClinicalTrials.gov, limiting independent verification.
No trial population resembles the healthy adults who buy GHRP-6 today for muscle or fat-loss purposes.
The pharmacokinetic study measured blood levels only, not any effect on health or performance.

Regulatory status

GHRP-6 is not approved as a medicine anywhere, for stroke or any other condition. The one clinical program that reached Phase III — GHRP-6 combined with epidermal growth factor for stroke — missed its primary efficacy endpoint. It is sold elsewhere only as an unregulated research chemical, and it is prohibited at all times in competitive sport by the World Anti-Doping Agency as a growth-hormone-releasing peptide (GHRP class, S2).

Primary research sources

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": Frontiers in Neurology 2024; PMID 38638315, DOI 10.3389/fneur.2024.1303402
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" (COURAGE-2): Journal of Clinical Neuroscience 2026; PMID 42462342, DOI 10.1016/j.jocn.2026.112195
Cabrales A, et al., "Pharmacokinetic study of Growth Hormone-Releasing Peptide 6 (GHRP-6) in nine male healthy volunteers": European Journal of Pharmaceutical Sciences 2012; PMID 23099431, DOI 10.1016/j.ejps.2012.10.006
Subirós N, et al., "Assessment of dose-effect and therapeutic time window in preclinical studies of rhEGF and GHRP-6 coadministration for stroke therapy" (animal/preclinical): Neurological Research 2016; PMID 26311576, DOI 10.1179/1743132815Y.0000000089

Full evidence entry (complete data, registry records, dosing evidence)

Mixed human evidence

Controlled human trials exist and disagree

At a glance

Also known as: Growth hormone-releasing hexapeptide
Class: Synthetic hexapeptide growth hormone secretagogue (GHRP family); the original prototype of the GHRP family
Derived from: A fully synthetic peptide, one of the earliest small peptides shown to mimic ghrelin's action on the growth hormone secretagogue receptor; not a fragment of a natural hormone
Registered human trials: 0
…with published results: 2
Largest human trial: 188 patients with acute ischemic stroke (Cuba, Phase III, published 2026) — GHRP-6 combined with epidermal growth factor (EGF) versus standard care; the trial missed its primary endpoint
Studied for: acute ischemic stroke (combined with epidermal growth factor, not as a standalone drug), acute growth hormone response (pharmacokinetic measurement), appetite/cachexia and tissue-protective effects (animal)
Dosing evidence: No human dose establishedThe only defined human dosing regimens come from a Cuban stroke research program combining GHRP-6 with a growth factor; no dose of GHRP-6 alone has ever been studied for the muscle-building, fat-loss, or anti-aging uses it is marketed for.
Regulatory status: Not approved as a medicine anywhere, for stroke or any other condition. The one clinical program that reached Phase III (GHRP-6 combined with epidermal growth factor, for stroke) missed its primary efficacy endpoint. It is sold elsewhere only as an unregulated research chemical.
Anti-doping status: Prohibited at all times by the World Anti-Doping Agency, as a growth hormone-releasing peptide (GHRP class, S2); named explicitly in laboratory anti-doping detection studies

What it is

GHRP-6 is a fully synthetic chain of six amino acids and the original member of the GHRP family — the first small peptide shown to mimic the natural hormone ghrelin and trigger a pulse of growth hormone from the pituitary gland. Related compounds like hexarelin and GHRP-2 were developed from the same research lineage.

It is not approved as a medicine anywhere, is sold as an unregulated research chemical, and is prohibited in competitive sport at all times.

What the studies actually found

Unusually for a compound in this library, GHRP-6 has a real, modern clinical trial program behind it — just not for the reasons it's marketed. A Cuban research group has spent years testing GHRP-6 combined with epidermal growth factor (EGF), not alone, as a possible neuroprotective treatment given intravenously in the first hours after an acute ischemic stroke.

A Phase I/II trial in 36 patients, published in 2024, found the combination safe, with fewer serious adverse events than standard care, and reported encouraging signals on disability and survival measures at three and six months — enough to justify a larger trial. That larger Phase III trial, in 188 patients and published in 2026, is the real test: on the primary, pre-specified analysis of all patients, it found no significant difference in disability, daily function, or survival between the treated and control groups. A secondary analysis limited to the most severe strokes suggested a possible benefit, but the trial's own primary result was negative.

Separately, animal and cell studies have reported GHRP-6 reducing lung and kidney injury in rodents. That is real preclinical work, but it has not been tested in people for those uses.

What exists in humans

No GHRP-6 trial is registered on ClinicalTrials.gov. The trials that exist are registered instead in the Cuban Public Registry of Clinical Trials, and all of them test GHRP-6 as part of a two-drug combination for stroke — not as a standalone compound, and not for muscle, fat loss, or anti-aging.

A separate, older Phase I study gave single intravenous doses of GHRP-6 alone to nine healthy men to measure how quickly it's cleared from the bloodstream — pharmacokinetics, not efficacy.

No human trial has ever tested GHRP-6, alone, for muscle growth, fat loss, recovery, or anti-aging — the uses it is most commonly marketed for today. The only outcome-level human evidence that exists is for a combination stroke therapy that missed its primary endpoint in its largest trial.

What doses have been studied in humans

The pharmacokinetic study gave nine healthy male volunteers a single intravenous dose — 100, 200, or 400 micrograms per kilogram of body weight — and tracked how the peptide moved through and cleared from the bloodstream over about 12 hours; it did not measure any health outcome.

The stroke trials gave hospitalized patients a fixed intravenous dose of GHRP-6 (3.5 or 5 milligrams), combined with epidermal growth factor, twice daily for seven days, starting within 12 hours of stroke onset — a regimen designed for that specific combination therapy in a hospital setting, not for self-administered use, and not tested in healthy people for any other purpose.

No study has given GHRP-6 alone, at any dose, to healthy adults over time to measure effects on muscle, fat, sleep, or aging. Amounts described online for those uses do not come from any of the studies above. They typically trace back to animal research, or to the stroke-trial doses, scaled or repurposed using conversions that estimate comparable exposure — not effectiveness or safety for an entirely different use in an entirely different population.

What remains unknown

Whether the "severe stroke" subgroup benefit is real or a chance finding, since the trial's primary, whole-population result was negative
Whether GHRP-6 contributes anything on its own, since every human efficacy trial tested it combined with a growth factor, never alone
Whether it has any effect on muscle, fat, or aging in healthy adults — this has never been tested
What repeated, long-term, self-administered use does, since every human trial ran for one week or less
What is actually in an unregulated vial sold as "GHRP-6" online

Registry and study records

Combination therapy of Epidermal Growth Factor and Growth Hormone-Releasing Hexapeptide in acute ischemic stroke: a phase I/II non-blinded, randomized clinical trial: PubMed · DOI: 10.3389/fneur.2024.1303402 — n=36, Cuban Public Registry of Clinical Trials RPCEC00000214, safety + functional outcomes
Phase III Open-Label, Randomized Clinical Trial of Epidermal Growth Factor and Growth Hormone Releasing Hexapeptide in Acute Ischemic Stroke: PubMed · DOI: 10.1016/j.jocn.2026.112195 — n=188 (COURAGE-2), missed primary endpoint on intention-to-treat analysis
Pharmacokinetic study of Growth Hormone-Releasing Peptide 6 (GHRP-6) in nine male healthy volunteers: PubMed · DOI: 10.1016/j.ejps.2012.10.006 — n=9, single IV bolus doses of 100, 200, or 400 µg/kg, pharmacokinetics only, no efficacy outcome measured
Assessment of dose-effect and therapeutic time window in preclinical studies of rhEGF and GHRP-6 coadministration for stroke therapy: PubMed · DOI: 10.1179/1743132815Y.0000000089 — animal (preclinical) dose-ranging study underlying the human stroke program

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Evidence last reviewed: September 2026. Peptide Proof reports what studies found. We do not give medical advice, dosing guidance, or treatment recommendations.