Acetyl Tetrapeptide-40

Acetyl Tetrapeptide-40 is a synthetic signaling peptide used primarily for anti-inflammatory/soothing and anti-redness benefits, typically at very low concentrations (often well under 1%). Peptides of this type are generally non-sensitizing and show low rates of irritation in leave-on use, with reactions more often attributable to the formula’s preservatives/solvents than the peptide itself. Given rare but possible idiosyncratic sensitivity in highly reactive or barrier-impaired eczema patients, it rates as very gentle rather than fully inert. Safety Notes: Acetyl Tetrapeptide-40 is an anti-inflammatory peptide primarily used in sensitive skin and redness-reduction products. In commercial formulations, it typically appears at 0.001-0.5% in standard consumer serums and creams, with supplier recommendations generally around 0.5-2%. High-strength specialized anti-redness treatments and professional-grade leave-on products available to consumers can reach up to 3% concentration for maximum efficacy in calming applications.