Adapalene is a medication used to treat acne vulgaris, a common skin condition that causes pimples, blackheads, and whiteheads. It belongs to a class of drugs known as retinoids, which are derivatives of vitamin A. Adapalene works by decreasing inflammation and regulating the growth of skin cells, which helps to prevent clogged pores and the formation of new acne lesions. It is available as a gel, cream, or lotion for topical application to the skin. Adapalene is generally well-tolerated but may cause skin irritation, dryness, or peeling in some people. It should be used as directed by a healthcare provider.