Boils and carbuncles

Boils and carbuncles are painful, pus-filled bumps that form under your skin when bacteria infect and inflame one or more of your hair follicles.

Boils (furuncles) usually start as red, tender lumps. The lumps quickly fill with pus, growing larger and more painful until they rupture and drain. A carbuncle is a cluster of boils that form a connected area of infection under the skin.

You can usually care for a single boil at home, but don't attempt to prick or squeeze it — that may spread the infection. Call your doctor if a boil or carbuncle is extremely painful, lasts longer than two weeks or occurs with a fever.

Symptoms Causes Risk factors Complications Prevention


Boils can occur anywhere on your skin, but appear mainly on your face, neck, armpits, buttocks or thighs — hair-bearing areas where you're most likely to sweat or experience friction. Signs and symptoms of a boil usually include:

  • A painful, red bump that starts out about the size of a pea
  • Red, swollen skin around the bump
  • An increase in the size of the bump over a few days as it fills with pus (can sometimes reach the size of a baseball)
  • Development of a yellow-white tip that eventually ruptures and allows the pus to drain out


A carbuncle is a cluster of boils that form a connected area of infection. Carbuncles often occur on the back of the neck, shoulders or thighs. Compared with single boils, carbuncles cause a deeper and more severe infection and are more likely to leave a scar. People who have a carbuncle often feel unwell in general and may experience fever and chills.

When to see a doctor

You usually can care for a single, small boil yourself. But see your doctor if you have more than one boil at a time or if a boil:

  • Occurs on your face
  • Worsens rapidly or is extremely painful
  • Causes a fever
  • Is more than 2 inches (5 centimeters) across
  • Hasn't healed in two weeks
  • Recurs

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