Definition of Acne:

Acne is a skin condition characterized by whiteheads, blackheads, and inflamed red pimples or "zits."

Causes, incidence, and risk factors:

Acne occurs when tiny holes on the surface of the skin, called pores, become clogged. Each pore is an opening to a canal called a follicle, which contains a hair and an oil gland. Normally, the oil glands help keep the skin lubricated and help remove old skin cells. When glands produce too much oil, the pores can become blocked, accumulating dirt, debris, and bacteria. The blockage is called a plug or comedone.

The top of the plug may be white (whitehead) or dark (blackhead). If it ruptures, the material inside, including oil and bacteria, can spread to the surrounding area and cause an inflammatory reaction. If the inflammation is deep in your skin, the pimples may enlarge to form firm, painful cysts.

Acne commonly appears on the face and shoulders, but may also occur on the trunk, arms, legs, and buttocks.

Acne is most common in teenagers, but it can happen at any age, even as an infant. Three out of four teenagers have acne to some extent, probably caused by hormonal changes that stimulate oil production. However, people in their 30s and 40s may also have acne.

Acne tends to run in families and can be triggered by:

• Hormonal changes related to menstrual periods, pregnancy, birth control pills, or stress
• Greasy or oily cosmetic and hair products
• Certain drugs (such as steroids, testosterone, estrogen, and phenytoin)
• High levels of humidity and sweating

Despite the popular belief that chocolate, nuts, and other foods cause acne, this does not seem to be true.