Acne

Acne is an inflammatory skin condition. The skin has sebaceous (oil) glands connected to hair follicles that contain fine hairs. In healthy skin, the sebaceous glands produce sebum, which empties onto the skin surface through a pore, an opening in the follicle. Keratinocytes, a type of skin cell, line the follicle. Normally, as the body sheds dead skin cells, the keratinocytes rise to the surface. 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 skin surface. The mixture of oil and cells allows bacteria that normally live on the skin to grow in the clogged follicles and cause inflammation — swelling, redness, heat and pain. When the wall of the clogged follicle breaks down, it releases bacteria, skin cells and sebum into the nearby skin, forming lesions or pimples.

For most people, acne tends to clear up by around the age of thirty, but some people in their 40s and 50s continue to have this skin problem.

Who can develop acne? People of all races and ages can develop acne, but it is most common in teenagers and young adults. When it occurs during adolescence, acne is more common in males. Acne can persist into adulthood, and it is then more common in women.

Types of acne. Acne causes several types of lesions, or pimples. Doctors refer to enlarged or clogged hair follicles as comedones. Types of acne include:

• Whiteheads: clogged follicles that stay beneath the skin and form a white bump.
• Blackheads: clogged follicles that reach the skin surface and open up. They look black on the surface because the air discolors the sebum, not because they are dirty.
• Papules: inflamed lesions, usually small and pink, that may be tender to the touch.
• Pustules or pimples: papules topped with pus-filled lesions that are white or yellow and may be red at the base.
• Nodules: solid, large and painful lesions located deep within the skin.
• Severe nodulocystic acne (sometimes called cystic acne): deep, painful, pus-filled lesions.

Causes of acne. Doctors and researchers believe that one or more of the following factors may lead to the development of acne:

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

Factors that can increase the risk of developing acne include:

• Hormones: an increase in androgens, male sex hormones, can lead to acne. These rise in both boys and girls during puberty and cause the sebaceous glands to enlarge and produce more sebum. Hormonal changes related to pregnancy can also cause acne.
• Family history: researchers believe you are more likely to develop acne if your parents had acne.
• Medications: certain drugs, such as those containing hormones, corticosteroids and lithium, can cause acne.
• Age: people of all ages can develop acne, but it is more common in adolescence.

Factors that do not cause acne but can worsen it:

• Diet: some studies show that certain foods can worsen acne. Research continues to study the role of diet as a causal factor.
• Stress.
• Pressure from sports helmets, tight clothing or backpacks.
• Environmental irritants, such as pollution and high humidity.
• Popping or picking at pimples.
• Rubbing the skin with harsh movements.