Acne forms when oil glands make too much sebum , an oily substance. At night larger amounts of sebum are created by the body, especially during puberty. Sebum blocks pores in the skin to form whiteheads , which form under the skin, and blackheads , which are open to the air. Blackheads are black because the air causes a chemical reaction with the oily debris inside, not because they are dirty. Yeast and bacteria in the skin cause whiteheads to become pimples that are inflamed,red, and sometimes pus-filled.
All teens experience some form of acne during puberty.
It is part of the natural process of change in your body. For some individuals, however, acne can be a severe and emotionally difficult illness. As men and women grow out of adolescence, acne usually gets better. Some acne, however, can continue for many years for some adults. Hormonal changes later in life can cause acne after adolescence.