A carbuncle is a skin infection that often involves a group of hair follicles. The infected material forms a lump, called mass, which occurs deep in the skin.

When you have more than one carbuncle, the condition is called carbunculosis.

See also: Skin lesion

Most carbuncles are caused by the bacteria staphylococcus aureus. The infection is contagious and may spread to other areas of the body or other people.

A carbuncle is made up of several skin boils (furuncles). The infected mass is filled with fluid, pus, and dead tissue. Fluid may drain out of the carbuncle, but sometimes the mass is so deep that it cannot drain on its own.

Carbuncles may develop anywhere, but they are most common on the back and the nape of the neck. Men get carbuncles more often than women.

Because the condition is contagious, several family members may develop carbuncles at the same time. Often, the direct cause of a carbuncle cannot be determined.

Things that make carbuncle infections more likely include:

• Friction from clothing or shaving
• Poor hygiene
• Poor overall health

Persons with diabetes, dermatitis, and weakened immune systems are more likely to develop staph infections.

A carbuncle is a swollen lump or mass under the skin. It may be the size of a pea or as large as a golf ball. The carbuncle may be red and irritated and might hurt when you touch it.

It may also:

• Grow very fast
• Have a white or yellow center (pustule)
• Weep, ooze, or crust
• Spread to other skin areas

Sometimes, other symptoms may occur. These may include:

• Fatigue
• Fever
• General discomfort or sick feeling
• Skin itching before the carbuncle develops

Your doctor will look at your skin. The diagnosis is primarily based on what the skin looks like. A skin biopsy may be done to help make the diagnosis or determine the exact type of bacteria involved.

Carbuncles usually must drain before they will heal. This most often occurs on its own in less than 2 weeks.

Placing a warm moist cloth on the carbuncle helps it to drain, which speeds healing. Gently soak the area with a warm, moist cloth several times each day. Never squeeze a boil or attempt to cut it open at home because this can spread the infection and make it worse.

You need treatment if the carbuncle lasts longer than 2 weeks, returns frequently, is located on the spine or the middle of the face, or occurs along with a fever or other symptoms. Treatment helps reduce complications related to an infection.

Your doctor may prescribe:

• Antibacterial soaps
• Antibiotics applied to the skin or taken by mouth

Deep or large lesions may need to be drained by a health care provider.

Proper hygiene is very important to prevent the spread of infection. Always wash your hands very well after touching a carbuncle. Do not re-use or share washcloths or towels -- this can cause the infection to spread. Clothing, washcloths, towels, and sheets or other items that contact infected areas should be washed in very hot (preferably boiling) water. Bandages should be changed frequently and thrown away in a bag that can be tightly closed.

Carbunculus may heal on their own. Others usually respond well to treatment. However, a carbuncle can return again and again for months or years following the first infection.

• Abscess of the brain, skin, spinal cord, or organs such as the kidneys
• Endocarditis
• Osteomyelitis
• Permanent scarring of the skin
• Sepsis
• Spread of infection to other areas

Call your health care provider if:

• A carbuncles does not heal with home treatment within 2 weeks
• Carbuncles come back often
• A carbuncle is located on the face or spine
• You have a fever, red streaks running from the sore, a lot of swelling around the carbuncle, or pain that gets worse

Good general health and hygiene may help prevent some staph skin infections. Such infections are contagious, so care must be taken to avoid spreading the bacteria to other people.

If you get carbuncles often, your doctor may give you antibiotics to prevent them.

Cohen J, Powderly WG. Infectious Diseases. 2nd ed. New York, NY: Elsevier; 2004.

Habif TP. Clinical Dermatology. 4th ed. St. Louis, Mo: Mosby; 2004.

Lopez FA. Skin and soft tissue infections. Infect Dis Clin North Am. Dec 2006; 20(4): 759-72, v-vi.