Acne cleansers contain exfoliating ingredients like Salicylic, Glycolic, Azelaic, Mandelic and Lactic acids that remove dirt, oil and impurities as well as helping to unclog blocked pores. Pores are cleared as dead surface skin is sloughed away, preventing blocked pores, which lead to acne.
By removing the most superficial surface layer of the epidermis, it allows the other active ingredients to penetrate the skin more effectively.