Acetyl hexapeptide-8 vs Copper tripeptide-1
It is a cream ingredient sold as a needle-free way to smooth expression lines. Two small trials disagreed: one showed less wrinkling, one showed none. A skin-care ingredient sold to firm skin, soften wrinkles and regrow hair. The one controlled human trial, of 13 patients, found no skin benefit.
Acetyl hexapeptide-8 has the stronger evidence, grade B (some human evidence) against grade C for Copper tripeptide-1. Neither is FDA approved.
Evidence
BSome human evidence
CAnimal and cell studies
Human studies cited
Animal or cell studies cited
Why the grade
For wrinkle reduction there is one randomized placebo-controlled trial in 60 Chinese adults showing a benefit, a 19-person split-face double-blind study showing none, a 26-patient uncontrolled series and the manufacturer's original volunteer study. Skin penetration work in human and animal skin finds very little of the peptide reaches the dermis, which leaves the mechanism in doubt. Small samples and conflicting results keep this at B.
For the skin anti-ageing use, the controlled human evidence is a single randomized trial of 13 patients after CO2 laser resurfacing, which found no objective difference in redness or wrinkles. The rest is gene-expression work in cultured cells, animal wound and lung-injury models, and cosmetic-company studies summarized in reviews written by the peptide's discoverer.
FDA
Cosmetic ingredient
Acetyl hexapeptide-8 (Argireline) is a cosmetic ingredient, and the FDA does not approve cosmetic ingredients before sale; products containing it are regulated as cosmetics so long as they claim only to improve appearance. It is not an approved drug for any use.
Cosmetic ingredient
Copper tripeptide-1 is a cosmetic ingredient and sits outside FDA drug approval; no copper tripeptide-1 or GHK-Cu product is approved by the FDA as a drug for any use. Injectable GHK-Cu sold online is not approved and is sold as a research chemical.
Sold for
Argireline is marketed as a needle-free alternative to Botox that relaxes expression lines when applied as a cream or serum.
Copper tripeptide-1 is marketed in serums as a collagen-building, wound-healing peptide that firms skin, softens wrinkles and regrows hair.
Studies say
One small randomized trial found a measurable reduction in eye-area wrinkles and another found none, while penetration studies show almost none of the peptide reaches the muscle layer, so the evidence supports a modest surface effect at best (grade B).
Cell and animal studies show it switches on repair genes and speeds wound closure, but the one blinded human trial found no measurable skin benefit over the control regimen, so the evidence is C.
Class
Neurotransmitter-inhibiting peptide
Carrier/copper peptide
Route
Topical
Topical