Acetyl Tetrapeptide-9 is a synthetic signal peptide marketed to stimulate dermal extracellular matrix components such as collagen and lumican, with the aim of improving skin firmness and density. Evidence is largely from manufacturer studies, and it is typically used at low concentrations in anti-aging formulations.
| Reported effect | How often | Notes |
|---|---|---|
Mild transient irritation or redness | Rare | Generally well tolerated; peptides are low-irritant, though reactions can occur in sensitive skin or from other formulation components. |
Contact allergy or sensitization | Very rare | Allergic reactions to synthetic peptides are uncommon but theoretically possible. |
Frequencies reflect typical cosmetic use reported in the literature, not a guarantee for your skin.