By the way, doctor: Are self-tanning sprays and lotions safe?
Q. I'd like to keep the tanned look I got during summer vacation. Are self-tanning lotions and sprays a good idea? Are they safe to use?
A. When you sunbathe, the sun's ultraviolet (UV) rays cause the skin to increase its production of a protective pigment called melanin, which manifests itself as a tan. Despite its association with good health and good looks, a tan is actually a sign of skin-cell damage, which can increase the risk for skin cancer and accelerate skin aging. The American Academy of Dermatology recommends using self-tanning lotions and sprays as an alternative to tanning in UV light from the sun or an indoor tanning bed.
You can buy self-tanning products over the counter and apply them yourself or go to a salon that offers spray-on or airbrush tans. The active ingredient in all of these products is dihydroxyacetone (DHA), a color additive approved by the FDA for tanning purposes. DHA binds to proteins in the top layer of skin, causing it to darken or stain. Thicker, protein-rich areas of your skin will stain more. That's why exfoliation of the elbows, knees, and ankles is recommended beforehand for even results. Because the coloring process takes place only in the surface layers of the skin, your "tan" lasts only as long as those layers stay on your body — about five to seven days. After that, you'll need a reapplication.