Hexapeptide-9 vs Acetyl octapeptide-3
It is put in anti-ageing creams to smooth wrinkles. The one controlled trial, of 96 adults, tested a changed version and was run by a cosmetics company. A face-cream ingredient sold to smooth lines around the eyes and forehead. It has not been properly tested on its own; one 24-person study used a mixed product.
Both sit at grade C: animal and cell studies. Neither is FDA approved.
Evidence
CAnimal and cell studies
CAnimal and cell studies
Human studies cited
Animal or cell studies cited
Why the grade
For wrinkle reduction, the evidence for standard hexapeptide-9 is unpublished supplier data, lab and mouse work, and a small split-face volunteer test of a delivery carrier. The one randomised double-blind trial, published in 2025 by employees of a cosmetics company, enrolled 96 adults but tested a chemically modified cyclised version against a low-concentration retinol and vehicle over 56 days, so the standard ingredient stays at C.
The only peer-reviewed human study found that tests a product containing SNAP-8 is a 2024 split-face study in 24 people, in which a microneedle patch carrying SNAP-8 together with other actives was compared with a plain hyaluronic acid patch for 28 days. SNAP-8 has not been tested on its own against placebo, and the claim that it beats Argireline comes from the manufacturer. That is grade C.
FDA
Cosmetic ingredient
Hexapeptide-9 is a cosmetic ingredient. Cosmetics do not go through FDA drug approval, so it has no approved indication and makes no drug claims; it is listed under its INCI name in skincare formulations.
Cosmetic ingredient
Acetyl octapeptide-3 (SNAP-8) is a cosmetic ingredient. The FDA does not approve cosmetic ingredients before sale and regulates products containing it as cosmetics provided they claim only to improve appearance; it is not an approved drug for any use.
Sold for
Hexapeptide-9 is marketed in anti-aging serums as a collagen fragment that signals skin cells to rebuild the dermis and smooth wrinkles.
SNAP-8 is sold as a longer, stronger version of Argireline that relaxes expression lines around the eyes and forehead when applied topically.
Studies say
The only controlled human trial tested a modified molecule and was run by the manufacturer, and the data for standard hexapeptide-9 are laboratory assays, so the grade is C.
The mechanism is borrowed from Argireline and the clinical support is one 24-person study of a microneedle patch that mixed SNAP-8 with other actives, which is too little to say SNAP-8 itself reduces wrinkles (grade C).
Class
Signal peptide
Neurotransmitter-inhibiting peptide
Route
Topical
Topical