Acne is a familiar skin disorder of the hair follicles and sebaceous glands. The glands become clogged, leading to pimples and cysts. Acne is very common; nearly 80% of Americans between ages 11 and 30 years old will be affected by it at some point. Acne most often begins in puberty, when the male sex hormones (androgens) increase in both boys and girls. This causes the sebaceous glands to become more active, which results in increased production of oil, or sebum. Sebum normally travels from the sebaceous glands to the skin surface via hair follicles. However, dead skin cells can plug the follicles, blocking the sebum. When follicles become plugged, ordinary skin bacteria begin to grow inside the follicles, causing inflammation. Incomplete blockage of the hair follicle results in blackheads. Complete blockage of the hair follicle results in whiteheads. Eventually, the plugged follicle bursts, spilling oil, skin cells, and bacteria onto the skin surface. In turn, the skin becomes irritated and new pimples or lesions begin to develop. Acne can be superficial (pimples without abscesses) or deep (when the inflamed pimples push down into the skin, causing pus-filled cysts that rupture and result in larger abscesses). Acne can occur anywhere on the body. However, it most often appears in areas where there’s a high concentration of sebaceous glands, including the face, chest, upper back, shoulders, and neck. Rising hormone levels during puberty are one cause of acne. In addition, acne is often inherited. Other causes may include hormone-level changes during the menstrual cycle; certain drugs (such as corticosteroids, lithium, and barbiturates); oil and grease from the scalp, mineral or cooking oil, or certain cosmetics; and bacteria inside pimples. Acne can be aggravated by squeezing the pimples or by scrubbing the skin too hard. Skin may also become irritated with friction or pressure from helmets, backpacks, or tight collars. Some environmental conditions such as pollution or humidity can irritate the skin as well. Enormous advances have been made in the treatment of acne—with many different strategies. The goal of acne treatment is to reduce the occurrence of new pimples, minimize scarring and improve appearance. Depending on the severity of acne, your doctor may prescribe topical medications (applied to the skin) or systemic medications (taken orally). In some cases, a combination of topical and systemic medications may be recommended. Although acne often is a chronic condition, even if it ends after adolescence, it can leave life-long scars, which typically look like “ice pick” pit scars or crater-like scars. Although proper treatment for acne may minimize scarring, several dermatological procedures may be helpful as well, including dermabrasion, chemical peels, collagen injections, and laser resurfacing.