Acne vulgaris is an inflammatory disease of the skin, caused by excessive secretion of oils from the sebaceous glands accompanies the plugging of the pores with naturally occurring dead skin cells (corneocytes) blocking hair follicles. Acne can be treated with vitamin A derivatives (tretinoin), and exfoliating and anti-inflammatory agents. The basic principle is to increase skin cell turnover promoting the extrusion of the plugged material in the follicle. Common exfoliating agents include salicylic acid which induce peeling of the top layer of skin preventing a build-up of dead skin cells and blocking pores. It also helps to unblock already clogged pores.