Smooth Serum4. 9 star rating Smooth Serum is a night treatment formulated with 3% Glycolic acid, 1% Lactic acid, and 1% Gluconolactone. This gentle AHA blend supports the appearance of skin texture and surface renewal, helping maintain the look of even skin tone. Key features: Combination of alpha hydroxy acids to support skin texture Supports the appearance of smoother, more even skin Can be used alongside products containing Retinal to maintain overall skin