Octocrylene

Octocrylene is a UVB/short-UVA sunscreen filter typically used around 2–10% to stabilize other filters and improve water resistance. Clinical experience and patch-testing data show it is generally tolerated but can cause irritant and, more importantly, photoallergic/allergic contact dermatitis in a meaningful minority—especially in eczema-prone or highly reactive patients and when combined with other sensitizing sunscreen filters. Given the real-world frequency of reactions and the high-risk context of leave-on, sun-exposed use, I score it as a moderate irritancy/sensitization risk requiring patch testing in sensitive populations. Safety Notes: In commercial OTC sunscreens and SPF moisturizers, octocrylene is commonly present at low levels (~0.5–2%) as a photostabilizer for avobenzone and to boost SPF, including in daily leave-on facial products. The highest concentrations observed in consumer-available leave-on sunscreens in major markets reach the EU maximum of 10% (EU Cosmetics Regulation), especially in high-SPF water-resistant lotions/sprays; rinse-off products rarely use it and when they do it is typically at the low end.