Sunless tanning products, also called self-tanners, can give your skin a tanned look without exposing you to harmful ultraviolet (UV) rays. The active ingredient in most sunless tanners is the color additive dihydroxyacetone (DHA). DHA reacts with dead cells in the skin's surface layer to temporarily darken your skin. The coloring gradually fades within a few days. Caution: Most self-tanners don't contain sunscreen. If you spend time outdoors, sunscreen is essential.