This supercharged daily brightening serum contains 20% L-ascorbic acid—a potent dose of the purest form of vitamin C—to visibly target dullness and discoloration. Skin-smoothing ectoin, an antioxidant powerhouse, is synergistically combined with ferulic acid to improve the look of skin tone and texture. Goop's serum is developed with a unique two-part system featuring a hydrating hyaluronic acid serum activator and is designed to be mixed before the first use to maximize performance and freshness. The result is noticeably smoother, softer skin with a remarkable glow.* <br><br>

Clinical measurements taken after four weeks of twice-daily use on 32 subjects between the ages of 30 and 55. Based on a four-week third-party consumer-perception study of 32 subjects between the ages of 30 and 55.