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What are carbuncles — is that red, painful bump on your skin a carbuncle?

Here’s how top dermatologists say you can prevent and treat this common skin condition.
Woman suffering from neck pain, waking up in the morning
Carbuncles can appear anywhere on your body, but they are most common on the face, neck, armpits, thighs and buttocks.Prostock-Studio / Getty Images stock

What is a carbuncle? A carbuncle is a connected group of boils that stem from an infection of the skin. “They are sometimes confused for a spider bite,” said Dr. Allison Arthur, a dermatologist and dermopathologist at Sand Lake Dermatology Center in Orlando, Florida, and a member of the American Academy of Dermatology. “It’s pretty common for people to come in thinking they have a spider bite when they have an abscess or carbuncle.”

Dr. Laura Ferris, associate professor and director of clinical trials in the dermatology department at the University of Pittsburgh Medical Center and a member of the American Academy of Dermatology, agrees: “Unless you saw the spider bite you, don’t assume it’s a spider bite. People mistake lots of things for spider bites.”

Symptoms of carbuncles

If you develop carbuncles and boils, you’ll notice red, tender bumps that contain pus. Over a few days, they get larger — up to two inches across — and more painful. “They can be pretty uncomfortable,” Ferris said.

The tip may eventually rupture, and the pus will flow out.

They can appear anywhere on your body, but they are most common on the face, neck, armpits, thighs and buttocks, according to the Mayo Clinic.

You may develop a single boil (also known as a furuncle versus carbuncle, which is a cluster of boils). Carbuncles are more serious, and you may notice other signs of infection such as a fever and chills.

Causes of carbuncles

Boils and carbuncles are caused by a bacterial infection, usually Staphylococcus aureus, which is often found on the skin or in the nose. The bacteria can enter the skin if there’s a small injury, bug bite or shaving nick.

You’re at higher risk for boils or carbuncles if you:

  • Come into contact with someone who has a staph infection
  • Have diabetes
  • Have skin conditions such as acne or eczema that can damage the skin
  • Have a weakened immune system
Detailed view of elbow with carbuncle or furuncle
“It’s pretty common for people to come in thinking they have a spider bite when they have an abscess or carbuncle,” said Dr. Allison Arthur.andriano_cz / Getty Images stock

Diagnosing carbuncles

Your dermatologist can diagnose boils and carbuncles by looking at them. If you keep getting boils or carbuncles, or they aren’t responding to treatment, your dermatologist can take a sample of pus and send it to a lab for testing.

Treatment for carbuncles

You can treat a small boil at home. The American Osteopathic College of Dermatology recommends putting a warm, moist washcloth over it three times a day for 20 minutes to help it heal. Covering it with an adhesive bandage can help keep the infection from spreading.

If it gets worse after several days, you develop another boil or you have a fever, see a dermatologist carbuncle treatments, say experts at the American Academy of Dermatology.

“Sometimes in the early stages people will just observe and see if it’s something that will go away. Often, as time goes on, more pus collects, the area gets red, swollen and painful, and they know it’s something that needs to be addressed,” Arthur said.

For treatment of carbuncles, a dermatologist can make a small incision in the boil to drain the pus. “You want to drain it before the infection spreads,” Ferris said. You’ll often also be prescribed a course of antibiotics.

You can’t always prevent boils and carbuncles, but there are steps you can take that may help. Arthur said that athletes who have skin-to-skin contact with other people and people who work out in gyms with shared equipment or shared mats could be exposed to bacteria.

To avoid exposure to bacteria at the gym, Arthur recommends:

  • Bringing your own mat for classes like yoga or Pilates
  • Wearing a T-shirt instead of a tank top when you use weight machines
  • Taking a shower as soon as possible after working out in a gym

In general, washing your hands regularly and keeping any cuts or abrasions covered with a bandage can also be helpful.