What are boils and carbuncles

A boil (or furuncle) is a skin infection that is usually caused by the bacteria Staphylococcus aureus (staph). Other bacteria or fungi can also cause boils.

A boil forms a lump that goes deep into the skin. It may have a central “head” filled with pus. Boils usually occur on the face, neck, armpits, buttocks, and thighs, but can appear anywhere on the body. They can be painful.

In most boils, the bacteria also infect hair follicles, the sacs that contain the roots of hair and oil glands. An infection of the hair follicles is called folliculitis. A boil can also develop from a cut in the skin.

A carbuncle is a group of boils located in one area of the body. Carbuncles may have more than one head that fills with pus. Some people can get boils or carbuncles over and over in one spot of the body.

People with certain illnesses like diabetes are more likely to get boils. Another risk factor is having another skin condition such as eczema, or conditions that reduce the skin’s ability to fight germs.

This skin infection can be spread to other people. On rare occasions, it can be serious, and cause infection of the bloodstream, infection of other body parts, or general infection of the body (sepsis). A serious infection with MRSA (methicillin-resistant Staphylococcus aureus) can also occur.

What are the symptoms of a boil?

A boil may start out as a sore, raised area that is pinkish red in color. Over time, the boil may fill with clear liquid or pus, and grow in size.

Symptoms of a boil include the following:

  • Swollen, red lump deep in the skin (Sometimes, a hair will grow from it.)
  • Painful, especially when touched, and in certain places on the body (such as the nose or ear)
  • Size can vary from pea to golf ball
  • May develop a central, whitish-yellow “head” that may break and release pus
  • May “weep” or ooze clear fluid, or develop a crust
  • May spread to surrounding skin, creating a carbuncle

What are the symptoms of carbuncles?

Carbuncles cause a deeper and more serious infection than boils, so their symptoms may be more severe. In addition to the same symptoms as seen in boils, carbuncles may also:

  • Cause fever and chills or other symptoms
  • Heal more slowly
  • Scar the skin