The Vitamin C 13 Serum

The active is 13% pure ascorbic acid, an antioxidant form of vitamin C that brightens overall tone and helps fade post-blemish dark spots with consistent use. It's buffered with hyaluronic acid, which holds water in the skin, and allantoin, which softens and calms, taking some of the edge off the pure vitamin C. Apply a few drops once a day after cleansing and any toner, then follow with moisturizer; morning use pairs well with sunscreen, which is worth wearing daily alongside it. Pure ascorbic acid can tingle or feel warm at first, so ease it in every other day if your skin is sensitive. Keep the bottle closed and out of light, since vitamin C oxidizes and can darken over time.