Acne is a common skin condition that happens when hair follicles under the skin become clogged. Sebum—oil that helps keep skin from drying out—and dead skin cells plug the pores, which leads to outbreaks of lesions, commonly called pimples or zits. Most often, the outbreaks occur on the face but can also appear on the back, chest, and shoulders.

Acne is an inflammatory disorder of the skin, which has sebaceous (oil) glands that connects to the hair follicle, which contains a fine hair. In healthy skin, the sebaceous glands make sebum that empties onto the skin surface through the pore, which is an opening in the follicle. Keratinocytes, a type of skin cell, line the follicle.  Normally as the body sheds skin cells, the keratinocytes rise to the surface of the skin. When someone has acne, the hair, sebum, and keratinocytes stick together inside the pore. This prevents the keratinocytes from shedding and keeps the sebum from reaching the surface of the skin. The mixture of oil and cells allows bacteria that normally live on the skin to grow in the plugged follicles and cause inflammation—swelling, redness, heat, and pain. When the wall of the plugged follicle breaks down, it spills the bacteria, skin cells, and sebum into nearby skin, creating lesions or pimples.

For most people, acne tends to go away by the time they reach their thirties, but some people in their forties and fifties continue to have this skin problem.

Causes of Acne

Doctors and researchers believe that one or more of the following can lead to the development of acne:

• Excess or high production of oil in the pore.
• Buildup of dead skin cells in the pore.
• Growth of bacteria in the pore.