Acne is an inflammation of the skin that causes blackheads, whiteheads, and red spots usually called "pimples" or "zits." The most common type of acne is acne vulgaris (vulgaris means common). Acne appears most often on the face, but can also be a nuisance on your chest, back, and upper arms. Acne affects about 90% of adolescents as well as 20% to 30% of individuals aged 20 to 40 years. It accounts for more doctor visits than any other skin problem.
Acne isn't life-threatening, but it can be upsetting and disfiguring and cause psychosocial problems. Acne can also lead to serious and permanent scarring.
Acne develops because your sebaceous glands are overactive. These glands normally produce small amounts of sebum, which is a thick mixture of oil and skin cells. When you have acne, these glands go into overproduction and the extra sebum can block your follicles and bacteria can move in, particularly the species called Propionibacterium acnes.
Hormones can cause an outbreak of pimples, or increase the number you get. The hormones that are active during puberty also trigger your sebaceous glands to produce more sebum. The hormones with the greatest effect on the oil glands are the androgens, the male hormones. Both men and women have androgens, but men have more.
In women, these hormones can also cause acne during the menstrual cycle, and that's why women often find that acne continues into adulthood. Hormones found in some types of birth control pills can also cause flare-ups of acne.
Eating junk food and chocolate normally has nothing to do with acne. Greasy hair and skin also doesn't cause acne, but they're often a sign of overactive sebaceous glands, which can cause acne. Research suggests that stress may worsen existing acne, but it doesn't cause it.
A tendency to get acne can run in families. It's more common among Caucasians than Asians or people of African descent.
Things that irritate your skin can also cause acne. These include:
- rubbing or friction from your clothes
- contact with a dog's tongue (e.g., after a friendly lick)
- skin contact with certain sports equipment
- certain cosmetics
- skin exposure to extreme temperatures
Taking corticosteroid medications can also cause an acne-like condition.