DHA (dihydroxyacetone) is used as a self-tanning agent. It does not produce a “real tan” by increasing skin melanin levels, but it can create a tan appearance by way of the development of a brown skin coloring. The action of DHA is limited to the upper layer of the skin and involves a reaction between DHA and skin proteins. DHA reacts with the amino acids and amino groups of the skin’s keratin-forming brown-colored compounds. The process takes place in the outer layers of the epidermis.