Oily skin occurs because of an overproduction of secretions from the skin's sebaceous glands. There is no direct cause for this overproduction other than genetics and heredity. These secretions create an oily, shiny glow on the surface of the skin. Often times oily skin is related to the appearance of acne because the greasy secretions can clog pores. In order to treat oily skin, one must use products and procedures that help to reduce oil production in the sebaceous glands.