Photostability of sunscreens

Sunscreens were originally designed to include mainly UVB-filters. Because of the deeper penetration of UVA light, causing photoaging and DNA damage, there has been a shift towards broad spectrum sunscreens. These broad spectrum sunscreens now include both UVA- and UVB-filters and other ingredients which possess antioxidant activity. Although sunscreens are regulated in most countries, photostability testing is not mandatory. Because of the ability of sunscreen ingredients to absorb UV-light and the complexity of most of these formulations, which may include more than one UV-filter, antioxidants and other formulation excipients, it is important that their photostability in combination is determined.

► A comprehensive review of the photostability of physical and chemical UV-filters. ► The major photoreactions of these UV-filters individually and in combination. ► The impact on their photostability when used in combination (broad spectrum). ► The effect of the formulation, antioxidants and excipients on photostability. ► The importance of photostability testing for sunscreens, currently not mandatory.