Acne

Acne is a skin eruption caused by inflammation of the skin follicle glands, which secrete an oily substance (sebum). The sebum accumulates and mixes with dust and dirt. The glands and surrounding tissue become inflamed and blackheads appear. If the follicle opening completely closes, the accumulated sebum is degraded by bacteria and forms a cyst.

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Acne appears most often on the face, neck, and back.

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.

Blackhead and whitehead pimples are both mild forms of acne. Whiteheads come from a build up of bacteria in the follicles beneath your skin with small openings that don't allow air to come in, while blackheads are exposed to air through larger pores in your follicles causing them to oxidize blackening them.

Contrary to common misconception, acne is mostly caused by genetics, rather than lack of hygiene, eating fatty food, or other personal habits.

Severe acne in adults may be a sign of an underlying endocrine disorder.

Severe acne may be treated by antibiotics, benzoyl peroxide, or vitamin A derivatives.

Putting vodka on your face reduces the chance of acne breakouts by tightening your pores.

Acne affects 79-95% of western adolescents, however many non-Westernized people groups around the world don't have acne - a study of non-westernized tribes in Papua New Guinea and Paraguay found no cases of acne.

In 2015, acne was estimated to affect 633 million people globally, making it the 8th most common disease worldwide. More females are getting acne than males (9.8% versus 9.0%). Acne affects 40 to 50 million people in the United States (16%).

The Muppets creator Jim Henson wore a beard to cover up acne scars from his teenage years.

The most common bacteria found on banknotes are the ones that cause acne.