DHA is the active ingredient in the most effective sunless tanning products. DHA, also known as Dihydroxyacetone, is a three-carbon sugar that is derived from sugarcane. When DHA is applied to the skin, it causes a chemical reaction with the amino acids in the outermost layer, (dead skin cells), to change it’s color. This is what happens when UV rays hit the skin as well. Spray tanning however does this safely at a quicker/stronger rate without the damaging affects of UVA and UVB rays let off by the sun and indoor tanning beds.