Ingredient in a cosmetic, drug, or pharmaceutical product considered to have a pharmacological effect. In the case of cosmetics, the effect on the skin must be documented by scientific evaluation, approved by the FDA, and adhere to FDA regulations. In addition, the amount and exact function of each active ingredient must be approved by the FDA. Active ingredients include such substances as sunscreen ingredients, skin-lightening agents, and anti-acne ingredients such as sulfur and benzoyl peroxide. The FDA also specifies that the active ingredient list must be first on a product label.