Acetyl Tetrapeptide-11

Acetyl Tetrapeptide-11 is a synthetic signal peptide typically used at very low concentrations (often well under 1%) in anti-aging formulas, and peptides in this class are generally non-stinging and well-tolerated in clinical and consumer safety data. While rare irritation can occur (often more related to the overall formula/preservatives than the peptide itself), its intrinsic irritancy potential is very low, making it appropriate for most sensitive-skin users with minimal risk. Safety Notes: In commercial leave-on skincare (serums, eye creams, anti-aging moisturizers), Acetyl Tetrapeptide-11 is most often dosed very low because it is commonly supplied as a diluted trade-material (e.g., in glycerin/water) and used at ~0.001–0.01% active, with some multi-peptide formulas using trace levels around 0.0001%. High-strength OTC specialty serums can reach about 0.05% active when the peptide is purchased as a higher-assay raw and positioned as a hero peptide, but concentrations above this are uncommon due to cost and diminishing practical formulation benefits. Rinse-off products, when they include it at all, tend to sit at the low end of this range due to short contact time.