In sunscreen, titanium dioxide is used as a barrier to keep the sun's ultraviolet (UV) rays from damaging your skin. It's processed into much smaller particles than what goes into food, called nanoparticles. In this form, it becomes transparent, and also absorbs UV light so it doesn't reach your skin.

TiO₂ is also used in oral pharmaceutical formulations, and the Pharmaceutical Excipients handbook considers nano-sized TiO₂ a non-irritant and non-toxic excipient. Despite the fact that TiO₂ submicron- and nano-sized particles are widely used as food and pharmaceutical additives, information on their toxicity and distribution upon oral exposure is very limited.