Styrene/Acrylates Copolymer

Styrene/Acrylates Copolymer is an inert film-forming polymer used at low levels in cosmetics to improve wear, texture, and water resistance, and it is not an active that alters skin biology or pH. Clinical experience and patch-test data generally show a low rate of irritation/sensitization for these high–molecular weight polymers, but the occlusive film can occasionally aggravate very reactive or compromised skin (e.g., eczema) by trapping heat/sweat or increasing stinging from other actives in a routine. Given the overall low intrinsic irritancy but nonzero risk in highly sensitive populations, a very gentle score is most appropriate. Safety Notes: In commercial skincare and makeup-adjacent skincare (SPF lotions, primers, setting/film-forming serums), Styrene/Acrylates Copolymer is often used at very low levels (~0.05–0.3%) as a stabilizer/texture modifier and to help suspend pigments or improve rub-resistance. Mid-range use (~0.5–3%) is common in leave-on sunscreens and long-wear/tint products for water-resistance and feel, while the highest consumer-available levels (~4–8%) are seen in strong film-forming, water-resistant leave-on formulations (e.g., long-wear SPF and “grip”/setting-type products) where a robust polymer film is desired; rinse-off products typically sit toward the low-to-mid end due to aesthetics and deposition limits.