Acne is an infection of the skin, caused by changes in the sebaceous glands. The redness comes from the inflammation of the skin in response to the infection. Oils from the glands combine with dead skin cells to block hair follicles. Under the blocked pore, oil builds up. Skin bacteria can then grow very quickly. This infection makes the skin become swollen and red, which becomes visible. The face, chest, back, and upper arms are most common places for acne to happen. Acne is common during puberty, when a person is turning from a child into an adult, because of high levels of hormones. Acne becomes less common as people reach adulthood. When severe, acne can often result in scarring. Even less severe cases can lead to scarring, if not properly treated.
Traditionally, patients with persistent to moderate acne have been treated with only topical or sometimes systemic antibiotics. Now doctors are able to treat acne with many types of medical devices.