e.l.f. Blemish Breakthrough Triple-Acid Resurfacing Serum is a hydrating night serum that works hard while you sleep to improve your skin's tone and texture. Dermatologically-developed. this serum is powered by a combination of Salicylic Acid. Tranexamic Acid. Polyhydroxy acids and Niacinamide. all working to brighten. clear and refresh your skin.