Once your skin no longer feels tight, uncomfortable and irritated, you might want to think about replacing this with an antioxidant serum, such as vitamin C, which will protect your skin against environmental aggressors like pollution. Dr. Hextall likes La Roche-Posay Pure Vitamin C10 Serum. If your skin is reactive (like mine) and you want to steer clear of vitamin C entirely, try something with niacinamide (vitamin B3) — also an antioxidant. “Niacinamide is great for someone with skin that is prone to pigmentation,” said Dr. Hextall. “It’s particularly good for acne-prone skin if your acne leaves behind marks,” she added. It also prevents water loss from the skin.