Combining glycolic acid and retinoids has been shown in clinical studies to fade acne scars and marks and is one of the few topical treatments that have shown efficacy when used nightly. This combination helps to renew skin cells and stimulate collagen synthesis, which in turn can fade pigmentation and fill in scars. Using both actives on the same night can be irritating, especially for beginners, so I recommend alternating these actives by starting to use each 2x per week and then working up to