An pus-filled, inflamed area of the skin, often an infected hair follicle. A more extreme and extensive form of boil involving several hair follicles is known as a carbuncle. The usual cause of a boil is infection with bacterium staphylococcus aureus. Recurring boils can occur in people with known or unrecognised diabetes mellitus or in those with other conditions where general resistance to infection is impaired.
Treatment can occasionally involve antibiotic drugs. However a boil that is opened to surgically to release the pus often heals rapidly without the need for drug treatment.