Collagen-fragment peptide · skincare
Hexapeptide-9 is a short synthetic peptide of six amino acids (Gly-Pro-Gln-Gly-Pro-Gln) that researchers describe as a collagen peptide1. The EU cosmetic ingredient database lists it as a skin-conditioning ingredient3, and it appears in creams and serums aimed at wrinkles and skin texture. It is not a drug.
The idea behind collagen-fragment peptides is that small pieces resembling collagen act as signals that encourage skin cells to make more collagen1,2. For hexapeptide-9 that rests mostly on laboratory and animal work. Two practical problems limit it: as a linear peptide it is quickly cut apart by enzymes, and it crosses the outer skin barrier poorly1,2. Researchers have tried two workarounds. One joins the peptide's ends into a ring, which its developers reported made it resist collagenase where the linear form was fully broken down1. The other pairs it with an ionic liquid made from GABA and lactic acid, which raised skin penetration several-fold in lab models and, in cell and animal work, engaged PPAR signaling and reduced markers of UV damage2.
Human evidence is limited and comes from modified versions. In a randomized, double-blind trial in 96 healthy Asian adults, a serum containing a ring-shaped (cyclized) form of hexapeptide-9 reduced the number, area and roughness of crow's-feet and forehead wrinkles over 56 days, and beat a retinol serum of matching strength on most measures1. The study was small and short, its authors work for the companies that made the cyclized peptide, and it did not include ordinary linear hexapeptide-9, the form found in most products. A second group, partly company-affiliated, paired hexapeptide-9 with a GABA-lactic acid ionic liquid; their lab, cell and animal experiments showed better penetration and less UV-induced damage, and they reported clinical experiments supporting the carrier2. ClinicalTrials.gov lists no registered trials of hexapeptide-9.
Not approved as a drug by the FDA; the EU lists it only as a cosmetic skin-conditioning ingredient3.
Human data are sparse. In the 96-person trial of the cyclized form, no treatment-related adverse events or skin reactions were reported over 56 days1. The published human data reviewed here cover only that cyclized form and that short period, so long-term effects of the common linear form are not well described. As with any topical product, irritation or allergy is possible.
This page is educational reference material about compounds studied in research settings. It is not medical advice, and nothing here is a recommendation to buy, possess, or use any compound. Research findings described are from published literature; individual compounds may not be approved for human use. Talk to a licensed clinician about anything that affects your health.
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