Damage to the hair follicle allows the bacteria to enter deeper into the tissues of the hair follicle and the subcutaneous tissue. Furuncles may occur in the hair follicles anywhere on the body, but they are most common on the face, neck, armpit, buttocks, and thighs. Furuncles are generally caused by Staphylococcus aureus but may be caused by other bacteria or fungi. A furuncle may drain spontaneously, producing pus and a solid core. More often they are opened by the individual, a parent, or a physician.
Furuncles can be single or multiple.
Some people have recurrent bouts with abscesses and little success at preventing them. Furuncles can be very painful if they occur in areas like the ear canal or nose. Furuncles by the nose should be treated by a health care provider. Furuncles that develop close together may expand and join together, a condition called carbunculosis . Skin or mucosal biopsy culture may show staphylococcus or other bacteria.