Abstract

All skin treatments that influence the hydrationdegree of the skin and/or its barrier function may have ameasurable influence on the radical generation. Thehighest effect was measured, when a solution of glycerineand water (50:50, w/w) was applied on the skin. Theamount of free radicals compared to untreated skin wasnearly doubled. Thus, there are no placebos, from adermatological viewpoint. Beyond the extinctioncharacteristics of UV filters, their distribution inside acosmetic formulation as well as their distribution pattern onthe skin’s surface are the most important parameters thatdrive the efficacy of sunscreens. The more homogeneousis the film of UV filters on the skin, the higher will be theprotective effect. The three model formulations, eachexemplary for common sunscreen sprays, lotions, andcreams, have very different performance on the skin.