What it is
Acetyl Tetrapeptide-9 is a short synthetic peptide consisting of four amino acids with an acetyl group attached to improve stability and skin affinity. It is used in leave-on products, including some sunscreens, as a conditioning agent marketed for support of skin smoothness and a firmer look. Peptides like this are typically used at very low concentrations within a broader formulation.
Safety & warnings
Short cosmetic peptides are generally well tolerated and are not common sensitizers at the low use levels in finished products. They are not known to be comedogenic.
Origin & sourcing
Synthetic; produced by peptide synthesis to yield a defined sequence of amino acids that is then acetylated.
Questions everyone asks
What does Acetyl Tetrapeptide-9 do in a formula?
It acts as a skin-conditioning peptide, included to support a smoother, firmer-looking complexion alongside other actives.
Is it animal-derived?
No. It is a synthetic peptide made by chemical synthesis rather than extracted from animal sources.