Boils and carbuncles are firm, reddish swellings about 5-10 mm across that are slightly raised above the skin surface. They are formed by bacterial infections of hair follicles and surrounding skin. Boils form pustules (small blister-like swellings containing pus) around the follicle and are sore to the touch. A boil usually has a visible central core of pus; a carbuncle is larger and has several visible drainage points. It is deeper and more extensive than a boil.

Boils occur most commonly on the face, back of the neck, buttocks, upper legs and groin, armpits, and upper torso. Carbuncles are less common than single boils and are most likely to form at the back of the neck.

Boils and carbuncles are common problems especially among adolescents and adults. People who are more likely to develop these skin infections include those with diabetes, alcoholism or drug abuse, poor personal hygiene...