Few skincare ingredients have come close to matching the anti-aging (and anti-acne and anti-dullness—we could go on, but you get the picture) wonder that is retinol. “Retinol helps to diminish and smooth fine lines and wrinkles, reverses sun damage and photo aging, and evens out dark spots and rough skin tones,” dermatologist and Goldfaden MD founder Dr. Gary Goldfaden says. The only issue is that as a powerful active ingredient, it can be irritating. When used in the wrong strength, retinols can be irritating and ineffective. Which is precisely why we called in the pros to help us determine what strength of retinol we all should be using.