What is acne? Acne is a skin condition that causes pimples or "zits." Whiteheads (closed comedones), blackheads (open comedones), red, inflamed papules, and nodules or cysts may develop. These most often occur on the face, neck, upper trunk and upper arm. Acne occurs when tiny pores on the surface of the skin become clogged. The pores can become plugged by substances on the surface of the skin. More commonly they develop from a mixture of the natural oils of the skin and the dead cells shed from the inside of the pore. These plugs are called comedones. Acne is most common in teenagers. But anyone can get acne. Causes of Acne Mechanical irritation of the affected skin area (e.g. by scratching, pressing, or pulling as well as wearing tight- fitting clothing such as headbands, bras, or backpacks) Application of cosmetics, hair products, and soaps. Certain medications (creams and tablets containing cortisone, lithium, some antiepileptics, etc.) Certain metabolic diseases Menstr...