A boil is a skin infection involving an entire hair follicle and nearby skin tissue.
Boils are very common. They are generally caused by the bacteria Staphylococcus aureus, but they may be caused by other bacteria or fungi found on the skin's surface. Damage to the hair follicle allows these bacteria to enter deeper into the tissues of the follicle and the tissue underneath.
Boils may occur in the hair follicles anywhere on the body. They are most common on the face, neck, armpit, buttocks, and thighs. There can be one or many boils.
A boil may begin as a tender, pinkish-red, swollen, firm area in the skin. Over time, it will feel like a water-filled balloon or cyst.
Pain gets worse as it fills with pus and dead tissue, and improves as it drains. It may drain on its own. More often the patient or someone else opens the boil.
Other symptoms may include:
The health care provider can usually diagnose a boil based on how it looks. A culture may show staphylococcus or other bacteria.
Boils may heal on their own after a period of itching and mild pain. More often, they increase in discomfort as pus collects.
Boils usually must open and drain before they will heal. This usually occurs in less than 2 weeks.
Deep or large boils may need to be drained with surgery by a health care provider. Treatment by a health care provider is needed if:
Careful hygiene is important:
Antibacterial soaps and antibiotics placed on the skin are of little help once a boil has formed. Antibiotics taken by mouth or given as a shot may help a more severe infection or if the boil returns.
Some people have repeated abscesses and are unable to prevent them.
Boils can be very painful if they occur in areas like the ear canal or nose. A health care provider should treat boils of the nose.
Boils that form close together may expand and join, causing a condition called carbunculosis.
Call for an appointment with your health care provider if boils:
The following may help prevent the spread of infection:
Habif TM. Bacterial infections. In: Habif TP, ed. Clinical Dermatology. 5th ed. Philadelphia, Pa: Mosby Elsevier; 2009:chap 9.
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