Topical vitamin C is a science-backed, dermatologist-favorite ingredient that may help slow early skin aging, prevent sun damage, and improve the appearance of wrinkles, dark spots, and acne. Vitamin C is an antioxidant, meaning it fights harmful free radicals (toxins) that come in contact with your skin from external sources like air pollution, or from inside the body as a result of normal processes like your metabolism. Free radicals can damage the skin, and applying topical vitamin C can combat free radicals and may improve the skin’s overall appearance.