Sugar-derived dihydroxyacetone (DHA) is a color agent that is most commonly present in self-tanners.
It reacts with the amino acids found within the upper layers of skin to create a darker color on the surface of the skin over a number of hours. DHA affects only the top layer of skin (and lasts only a few days due to the high turnover of skin cells), and therefore does not trigger the production of melanin and does not offer effective protection against UV radiation.