How Self-Tanners (DHA) work?

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 the 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. There is much evidence to suggest that the process is similar to Maillard reaction, also known as “non-enzymatic browning”. In this reaction, reducing sugars combine with amino acids, proteins and peptides to form various amino carbonyl compounds via a complex chain of reactions, which is not yet completely understood. According to the Maillard reaction, pyruvic acid and other hydroxycarbonyl compounds are probably formed from dihydroxyacetone, which, after further reaction steps, form brown compounds. The development of color takes anywhere from 2 – 4 hours and the intensity is dependent on the formulation concentration of the DHA in the product.