Oregon Esthetician State Board

What active ingredient in self-tanning lotion reacts with the skin to darken it?

1. Alpha hydroxy acid

2. Retinol

3. Dihydroxyacetone

4. Vitamin C

The correct answer is: Dihydroxyacetone

The active ingredient in self-tanning lotion that reacts with the skin to create a darkened appearance is dihydroxyacetone (DHA). DHA is a colorless sugar that interacts with the amino acids in the epidermis (the outer layer of the skin) through a process called the Maillard reaction. This chemical reaction results in browning of the skin, mimicking a natural tan from sun exposure. Unlike other ingredients mentioned, such as alpha hydroxy acid, retinol, and vitamin C, which serve different purposes in skincare (exfoliation, anti-aging effects, and antioxidant protection, respectively), DHA specifically targets the skin's surface to provide that tanned effect. Therefore, it is the key ingredient for achieving the desired color in self-tanning products.