Potential Beneficial Effects of Mineral Sunscreens on Acne-Prone Skin

Abstract

Sunscreens are critical products used against harmful ultraviolet (UV) radiation. However, beyond the effect of sun protection, the inorganic UV filters zinc oxide and titanium dioxide have shown antimicrobial activity. This study aimed to evaluate the potential additional beneficial effects of mineral sunscreens containing zinc oxide and titanium dioxide as antimicrobial agents on acne-prone skin. Transepidermal water loss, skin hydration, and skin pH of twelve volunteers were measured before and 2 h after the application of three mineral sunscreens. The antimicrobial activity of the mineral sunscreens was determined against Cutibacterium acnes, Staphylococcus aureus, and Staphylococcus epidermidis in a time-kill test. The studied mineral sunscreens did not affect either the stratum corneum hydration or its integrity, but they increased the skin pH from 4 to 6, which could impact the skin microbiota balance. At the same time, the tested mineral sunscreens inhibited Cutibacterium acnes, Staphylococcus epidermidis, and Staphylococcus aureus. This study suggests that the two UV filters can have positive effects on acne-prone skin and, thus, extend the benefits of photoprotective formulations. Nevertheless, further research is currently being conducted.