What is the main ingredient in most self-tanners?

The main ingredient in most self-tanners is Dihydroxyacetone (DHA). DHA is a colorless sugar that reacts with the amino acids in the outer layer of the skin, resulting in a temporary darkening effect, which mimics a tan. This reaction occurs through a process called the Maillard reaction, where the sugar interacts with the skin's proteins. The effects typically last for several days, gradually fading as the skin naturally exfoliates.

Other ingredients, such as oxybenzone and avobenzone, are primarily used in sunscreens for their UV-filtering properties rather than for tanning purposes. Titanium dioxide is often used in sunscreens as a physical blocker but does not contribute to the tanning effect that DHA provides. Therefore, DHA is recognized as the key active ingredient responsible for the bronzing effect in self-tanning products.