Mandelic acid has a bigger molecular structure than other AHAs so it penetrates more slowly into the stratum corneum and requires a longer exposure time. For this reason it does not cause irritation or pruritus on the skin. Further it increases collagen, elastin and glycosaminoglycans synthesis in the papillary dermis.
Glycolic acid has a high skin tolerance and a small molecular size. Because of that it has a great transepidermal penetration capacity. Its keratolytic activity favors the exfoliation of the superficial layers of the stratum corneum by altering the cohesion of the corneocytes. It stimulates cellular regeneration, promotes the synthesis of glycosaminoglycans, increases the level of hydration of the epidermis and reinforces the natural barrier function of the skin. Also promotes penetration of other acids.