A furuncle or carbuncle is a boil formed by the bacterium Staphylococcus aureus. Cystic acne, which occurs more often in teens, is an abscess formed when oil ducts become clogged. Hydro-adenitis suppurativa is an illness in which multiple abscesses form in the sweat gland openings in the armpits and groin. Pilonidal cysts can occur in the crease of the buttocks, usually after long trips that involve sitting. Boils occur when bacteria get into a deep break in the skin such as an ingrown hair, a foreign body such as a splinter, acne, or a plugged sweat or oil gland.
Boils are more likely to occur in people with diabetes or kidney failure or immune deficiency.
Most boils will drain on their own with frequent applications of hot soaks or hot packs. However, some abscesses, especially large ones, will need to be drained or lanced by a health-care professional. Occasionally, the skin around a boil becomes infected. In these cases, antibiotic treatment may be necessary. Seek medical attention for any boil associated with a fever, any pilonidal cyst, or any boil that does not improve rapidly with heat applications.