Boils (Furunculosis):
Information for adults

Boils (furuncles) are painful pus-filled bumps on the skin resulting from the deep infection of a hair follicle. The infection is usually caused by a type of bacteria called Staphylococcus aureus (staph). Many people are "carriers" of the staph germ, meaning that it normally lives on their skin or in their nose without doing them any harm. Tiny breaks in the surface of the skin (such as those caused by friction or scratching), however, can help the germ gain entry into and infect the hair follicle, resulting in a boil.

Boils may resolve with simple self-care measures, but the infected fluid (pus) needs to drain in order for them to heal completely. Many boils drain of their own accord, or they can be lanced by a health care professional. Antibiotics may also be prescribed. Untreated boils can enlarge or grow together to form a giant multi-headed boil (carbuncle). Rarely, the infection in the skin can get into the bloodstream, leading to serious illness.