Pimple is a red, raised skin blemish that usually contains pus. The most common cause of pimples is acne, a skin disorder that frequently occurs among teen-agers.

Acne consists of various kinds of blemishes that appear on the face, upper chest, and back. It is caused by hormone changes during the teen years. One kind of hormone stimulates the oil glands, which then grow larger and produce much oil. The pores (openings) of the oil glands at the skin surface are easily plugged, and oil accumulates under the plugs. A plugged pore forms a blemish called a blackhead or whitehead. Pimples are caused by the acne bacillus, a germ that thrives in the backed-up oil. The germ makes irritating substances from the oil, causing redness and pus. Mild acne can be treated by washing affected areas regularly and using such nonprescription medicines as benzoyl peroxide. Severe acne should be treated by a doctor. Pimples should not be squeezed. Squeezing may cause scarring.

Other causes of pimples include infections by staphylococcal and streptococcal bacteria. Unlike acne, in which there are many blemishes, these infections usually start with one pimple. This pimple may develop into a boil. Doctors treat these infections with antibiotics.

Many black men with curly facial hair develop pimples where they shave. These painful "shaving bumps" occur because the coarse, curved whiskers tend to grow into the skin after shaving. Growing a beard relieves this condition.