How safe are fake tans?

They are the safest way to tan. Dihydroxyacetone (DHA) is the main ingredient in self-tanners that tan your skin. It is a type of sugar that reacts with the skin's amino acids to create melanin, that tan color you see. There are no known side effects to the use of DHA on the skin. However, some reported that over long periods of inhaling DHA from spray tanning, they developed breathing problems....but this is still unproven. Just to be on the even safer side, you can always use a self-tanning lotion instead of spray.