GHRP-6: What the Evidence Actually Shows

GHRP-6 — growth hormone-releasing hexapeptide — is sold in the peptide-research market as an appetite-stimulating, muscle-building GH secretagogue, usually alongside GHRP-2 or CJC-1295. That market framing skips something real and specific this article found by checking the current literature directly rather than repeating the standard "unapproved bodybuilding peptide" summary: GHRP-6 is also the active ingredient in a genuine Cuban state drug-development program, with a real Phase III human trial completed in 2026 — for acute ischemic stroke, an application that has nothing to do with why it's sold in the U.S.

What it actually is

GHRP-6 — His-D-Trp-Ala-Trp-D-Phe-Lys-NH2 — was the first of the growth hormone-releasing peptides extensively studied in humans, and its own founding pharmacology paper is worth reading precisely: a 1984 animal study (not a human trial, stated plainly) found the hexapeptide "specifically elicits a dosage-related release of GH in vitro and in vivo without a concomitant release of LH, FSH, TSH, or PRL," active across rats, monkeys, lambs, calves, and chicks, given IV, SC, or IP³. That original "specific for GH alone" finding turned out not to hold cleanly once human pharmacology was studied more closely — a 2026 peer-reviewed review states that in controlled human studies, GHRP-6 "robustly stimulates pulsatile GH secretion" but also produces "transient increases in cortisol and prolactin," a strong, consistent appetite-stimulating effect via ghrelin-pathway signaling, and measurable effects on sleep architecture⁵. It activates the ghrelin receptor (GHSR-1a), the same target GHRP-2 and hexarelin bind — our GHRP-2 evidence review and our Hexarelin evidence review cover those two related compounds directly.

CIGB-500: a real Cuban cardioprotection drug-development program

Here's what the standard bodybuilding-market framing of GHRP-6 omits entirely: GHRP-6 is the active pharmaceutical ingredient in CIGB-500, an investigational drug developed by Cuba's Center for Genetic Engineering and Biotechnology (CIGB). A 2025 published toxicology study states this plainly in its own opening sentence: "CIGB-500 is a product whose active pharmaceutical ingredient is GHRP-6 ... a synthetic peptide that allows the rescue of cardiac mass affected during Acute Myocardial Infarction²." That study — a real, completed 28-day repeated-dose toxicology assessment in beagle dogs, given CIGB-500 intravenously at doses up to 2,000 mcg/kg/day — found transient, non-adverse clinical signs (hypersalivation, reduced heart rate, changes in respiration) at the higher doses, with no adverse macroscopic or microscopic organ changes, and a no-observed-adverse-effect level (NOAEL) at the highest dose tested². This is genuine, current, regulatory-track animal toxicology work for a real drug-development program most GHRP-6 marketing never mentions.

A real Phase III human trial — for stroke, not muscle

More substantial still: a real, published, multicenter, randomized, open-label Phase III human trial — COURAGE-2, sponsored by the same Cuban institute, enrolling 188 patients — tested intravenous EGF (75 micrograms) plus GHRP-6 (5 mg), given twice daily for 7 days, against standard care in acute ischemic stroke, published in 2026¹. Reported at the precision this trial's own results earned, in the order they matter: the trial missed its primary endpoint. In the full intention-to-treat population, there was no significant difference in the modified Rankin Scale, Barthel Index, or survival between the treated and control groups. Severe adverse events occurred in 48 of 188 patients overall — none classified as treatment-related by the trial's own investigators — with a numerically higher rate in the treated arm (30/95 vs. 18/93) that did not reach statistical significance (odds ratio 1.92, 95% CI 0.981-3.767)¹. That is the honest headline result: a real Phase III trial that did not confirm its own primary hypothesis.

A real, pre-specified subgroup finding is also worth reporting precisely, without inflating it past what the trial itself claims. Among patients with severe stroke (NIHSS score of 15 or higher at baseline, n=27) — a smaller, secondary population — the treated group showed significantly less disability at six months (mean modified Rankin Scale 2.6 vs. 4.7 in controls, p=0.03) and significantly lower mortality risk (hazard ratio 0.18, p=0.045), alongside a greater reduction in infarct volume in the middle cerebral artery territory at 30 days¹. The trial's own conclusion states this precisely: "The Courage-2 study missed the primary endpoint but suggested potential benefit in moderate-to-severe stroke, warranting further studies targeting this subpopulation¹." That is a real signal in a real controlled trial — and it is explicitly a subgroup finding awaiting confirmation, not a demonstrated result for stroke patients generally.

The human GHRP-family literature more broadly

Separately from the Cuban stroke/cardioprotection program, a comprehensive human pharmacology review of the whole GHRP-6/GHRP-2/hexarelin family — itself now nearly three decades old but still the most complete single account of this class's human dosing history — documents that GHRP-6's GH-releasing activity is "marked and dose-related after intravenous, subcutaneous, intranasal and even oral administration," undergoes partial desensitization with continuous infusion but less with intermittent dosing, and has shown some effect on height velocity in short children during chronic treatment⁴. A 2026 narrative review of this same peptide class, focused specifically on the unregulated self-administration market, notes that off-label users routinely extrapolate GHRP-6's endocrine effects into claims of improved body recomposition through enhanced protein synthesis and lipolysis — but states plainly that "direct evidence for meaningful changes in body composition outcomes in humans remains limited and should be interpreted cautiously⁵." That is the honest state of the evidence for the actual reason GHRP-6 is sold in the U.S. market today: real, well-documented acute GH-releasing pharmacology, and no controlled trial evidence for the body-composition claims built on top of it.

The regulatory picture

FDA's own live-fetched safety-risk page for compounded bulk drug substances carries a dated GHRP-6 entry (September 29, 2023): "Compounded drugs containing GHRP-6 may pose risk for immunogenicity for certain routes of administration due to the potential for aggregation and peptide-related impurities. FDA has identified limited safety-related information, but the available data reveal safety concerns including potential effect on cortisol and increase in blood glucose due to decreases in insulin sensitivity⁶." Separately, FDA's current 503A Bulks List — fetched live as a PDF and text-searched directly — lists "GHRP-6" by name under Category 3, "Bulk Drug Substances Nominated Without Adequate Support⁷": a nomination FDA found didn't include enough supporting information to complete an evaluation, the same category GHRP-2 sits in. DailyMed's structured-product-label search returns zero results for "GHRP-6" — no FDA-approved U.S. human drug product exists. openFDA's FAERS database returns zero reports for "GHRP-6" as of this article's live query — genuinely fewer adverse-event reports on file than most compounds in this corpus, though a small FAERS count reflects reporting volume, not necessarily safety.

What this means if you're considering it

None of the 31 providers this site's own reviews cover sell GHRP-6 — this site's own identity-layer research confirms it is not tagged to any reviewed seller. The picture that emerges from checking this compound's actual current literature, rather than repeating its marketing framing, is genuinely split: a real Cuban state drug-development program (CIGB-500) has taken GHRP-6 through completed animal toxicology and a real, if primary-endpoint-missing, Phase III human trial for acute stroke — evidence with essentially nothing to do with the bodybuilding/anti-aging use it's actually sold for in the U.S., where the body-composition claims remain, in a 2026 review's own words, unsupported by controlled human evidence. Our reconstitution calculator does the vial-to-syringe arithmetic on the numbers you enter — it cannot confirm a vial matches CIGB-500's studied formulation or dose, since no U.S.-marketed reference product exists to check it against. Readers comparing this compound against its closest relatives can find our GHRP-2 evidence review and our Hexarelin evidence review here, and our CJC-1295/Ipamorelin evidence review covers the newer generation of GH secretagogue engineered specifically to avoid the broader cortisol/prolactin effects this older class shares.