Benzophenone

Benzophenone is a UV absorber/fragrance fixative used at low but functional concentrations, and it is a well-documented contact allergen with reported photoallergic and allergic contact dermatitis in patch-testing populations. While many users tolerate it, sensitization risk and flare potential in eczema-prone or highly reactive skin make it inappropriate to treat as “gentle,” so I score it as a moderate irritant/allergen where patch testing is prudent. Safety Notes: In modern consumer skincare, benzophenone is most often encountered as a low-level UV absorber/photostabilizer or fragrance/fixative-related trace in leave-on products, commonly around 0.01–0.1% when used intentionally. The highest OTC concentrations observed in specialty sun-care and some legacy/older-technology formulations approach the EU maximum permitted level of 0.5% (Annex VI UV filter use); higher levels are generally avoided due to sensitization/phototoxicity concerns and regulatory limits. Rinse-off products typically sit at the very low end or are absent, while leave-on (especially sun-exposed) products represent the upper end of the market range.