ABSTRACT
There are very few cosmetic ingredients that rely on chemical reactions with the biological surfaces to create more permanent effects; in skin care, these types of ingredients include self-tanning agents. The only approved self-tanning agent is dihydroxyacetone (DHA), which has been used well over 40 years and has unsurpassed safety over sun-induced tanning. Formulation with DHA is often regarded as somewhat challenging due to its instability. Products containing DHA remain stable over a long time if some fundamental rules, such as selection of ingredients, avoidance of high temperature, and adjustment of pH to acidic (3.0 to 4.5), are followed. Experimental and clinical evidence have shown that DHAcontaining products provide some photoprotection; however, for better photoprotection, as recommended, always use DHA in combination with non-nitrogencontaining organic sunscreen. This photoprotective property of DHA has been utilized in the treatment of psoriasis. In this chapter, DHA, the primary active for sunless tanners, is reviewed and described at length.
