Acne is the most common skin ailment in the U.S., causing 25% of all visits to dermatologists and affecting about 75% of people in their twenties and thirties. Usually beginning in adolescence, it is an inflammatory condition affecting the pilosebaceous unit of the skin. The pilosebaceous unit consists of three parts: a hair follicle, a sebaceous gland, and a duct which connects the sebaceous gland to the skin’s surface. These units are more numerous in certain areas of the body, including the face, upper chest, and back.
As acne develops, sebaceous glands in the pilosebaceous unit begin overproducing sebum (usually as a consequence of a hormone called an androgen), resulting in extra oil. Bacteria in the hair follicles start to flourish and multiply, producing fatty acids which are irritating to pores in the skin. At the same time, openings of the pores become clogged with oil, skin cells, and debris. This forms a plug or comedo (a clogged pore). One type of comedo is a whitehead, the other is a blackhead.