An antioxidant serum is a skincare product that contains antioxidants, which protect the skin from damaging free radicals and help prevent and repair signs of aging. Free radicals are unstable atoms that can break down cells and are linked with a number of illnesses, as well as signs of aging. Antioxidants bind to free radicals and donate their electrons, stopping free radicals from stealing electrons from skin cells and causing damage. The best antioxidant serums contain a wide range of antioxidants, such as retinols, vitamin A derivatives, alpha-lipoic acids, vitamin C, vitamin E, coenzyme Q10, lycopene, and niacinamide. Antioxidant serums can help the skin combat or recover from UV radiation, air pollution, cigarette smoke, and aging. Some of the benefits of using an antioxidant serum include reducing lines and wrinkles, hyperpigmentation, and inflammation, which can lead to smoother and brighter skin. Antioxidant serums can be beneficial at nearly any age, starting in the 20s, and should be applied as the first step after washing the face.