Differin is a retinoid medication that is applied directly to the skin to treat acne. The active ingredient in Differin, adapalene, is derived from Vitamin A and works by reducing the production of skin cells and increasing the turnover of surface skin cells. This dual action helps to clear acne and prevent the symptoms of acne from recurring. Additionally, Differin helps to regulate the production of oil in the skin, which can further help to prevent the formation of acne.