Antioxidants in sunscreens: which and what for?

UV radiation promotes the generation of reactive oxygen (ROS) and nitrogen (RNS) species resulting in skin damage. Cosmetic industries have adopted the strategy to incorporate antioxidants in sunscreen formulations, aiming to prevent/minimize the UV-induced oxidative damage, boost photoprotection effectiveness and to mitigate skin photoaging. This work aims to characterize the frequency of the use of antioxidants in commercial sunscreens. Photoprotective formulations currently marketed in parapharmacies and pharmacies were analysed concerning the composition described on the label. As a result, pure compounds with antioxidant activity were found. The majority of the sunscreen formulations contained antioxidants and the most frequently used were vitamin E and derivatives. A more thorough analysis of these antioxidants is also provided, unveiling the top of the antioxidant ingredients found in sunscreens and their mechanisms of action. A critical appraisal of the scientific evidence regarding their effectiveness is also performed. In conclusion, this work provides an up-to-date overview about the use of antioxidants in commercial sunscreens for a better understanding of the advantages associated to their use in photoprotective formulations.