Dihydroxyacetone, DHA

Dihydroxyacetone, commonly referred to as DHA, is the active ingredient in most sunless tanning and self tanning products. DHA is a non-toxic colorless sugar, it's the sunless tanner chemical responsible for giving us the tan color. When DHA is applied to the skin it reacts with the amino acids of dead skin cells in the outermost layer of the epidermis (the stratum corneum) forming melanoidin-like brown-colored compounds. The concentration of DHA in sunless tanning lotions and self tanning towelettes determines the shade of tan as well as the rate with which the tan develops.

Once applied DHA takes 2 to 3 hours to fully react with the skin. After this has occurred DHA cannot be washed off, instead the color fades as the upper layers of the epidermis are naturally sloughed off over a 5 to 7 day period. To maintain a sunless tan, regularly reapply self-tanning products every 3 to 4 days.

One final word on DHA, there are people who may experience an allergic reaction to dihydroxyacetone.