Patient Basics: Boil and Carbuncle

A boil (furuncle) is a painful, pus-filled lump that forms when a hair root gets infected, usually by staph bacteria. A carbuncle is a group of boils joined together under the skin. Many small boils heal with warm compresses at home. Large boils and carbuncles often need a doctor to drain them.

Key points

• Boils start as a tender red bump that fills with pus over a few days.
• Warm, damp compresses several times a day help a boil open and drain.
• Don’t squeeze, pop or cut a boil. This can push the infection deeper.
• See a doctor for a large boil, a carbuncle, a boil on the face, or fever.
• Boils that keep coming back can often be stopped by clearing staph from the skin and nose.

What causes boils

Staphylococcus aureus (staph) bacteria live harmlessly on the skin and inside the nose of many people. When they get into a hair follicle, often through a small cut, scratch or shaving nick, they can cause an infection. The body sends white blood cells to fight it, and pus collects in a pocket under the skin.

Some staph strains resist common antibiotics. This kind is called MRSA (methicillin-resistant Staphylococcus aureus). MRSA now causes many boils in the U.S., including in healthy people.

You’re more likely to get boils if you:

• Live with someone who has boils, or share towels, razors or sports gear
• Have skin that rubs against clothing or other skin, such as the thighs, buttocks or armpits
• Have diabetes, obesity or a weak immune system
• Have eczema or another skin condition that breaks the skin
• Play contact sports, are in the military, or live in crowded housing such as a jail or shelter

What a boil looks like

Boil

• A red, tender bump, often on the face, neck, armpit, buttocks or thigh
• The bump grows over a few days and becomes softer as pus collects
• A white or yellow tip forms at the top
• The boil may burst and drain, which usually eases the pain

Carbuncle

• A larger, deeper, swollen area made of several connected boils, often on the back of the neck, the back or the thighs
• Several openings that drain pus
• Fever, chills and tiredness, which happen more often with carbuncles

Carbuncles heal more slowly and are more likely to leave a scar.

How they’re diagnosed

A doctor can usually tell by looking at the skin. If a boil is drained, the pus may be sent to a lab to check for MRSA and find the right antibiotic. If you get boils often, your doctor may test your blood sugar for diabetes, or swab your nose to see if you carry staph there.

Lumps that keep coming back in the armpits, groin or under the breasts may be a long-term skin condition called hidradenitis suppurativa. It needs different treatment, so mention this pattern to your doctor.

How boils and carbuncles are treated

At home

• Hold a clean washcloth soaked in warm water on the boil for 10 to 15 minutes, three or four times a day. The heat boosts blood flow and helps the pus gather and break through the skin.
• When it drains, gently wash the area with soap and water, then put a fresh bandage over it. Change the bandage often.
• Wash your hands well after touching the boil.
• Take acetaminophen or ibuprofen for pain if needed.

Most small boils drain and heal within one to two weeks.

From a doctor

• Draining. For a large boil or a carbuncle, a doctor numbs the skin, makes a small cut and lets the pus out. This is the most important treatment. A deep pocket may be loosely packed with gauze for a day or two.
• Antibiotics. These may be added for a carbuncle, several boils, a fever, spreading redness, a boil on the face, or a weak immune system. Your doctor will choose one that works against MRSA if needed. Take every dose.

Boils that keep coming back

If you get boils again and again, your doctor may suggest a plan to clear staph from your body, sometimes for everyone in your home. This may include:

• An antibiotic ointment, such as mupirocin, put inside the nose for several days
• Washing with an antiseptic skin wash, such as chlorhexidine, or taking diluted bleach baths
• Washing towels, sheets and clothes in hot water
• Cleaning shared surfaces such as doorknobs, phones and gym equipment

Preventing spread

• Keep a draining boil covered with a clean, dry bandage.
• Don’t share towels, washcloths, razors, clothing or sports gear.
• Wash your hands often, especially after touching a boil or changing a bandage.
• Avoid contact sports, swimming pools and hot tubs until the boil has healed.
• Throw used bandages away in a closed bag.

When to see a doctor

• A boil larger than about half an inch, or one that hasn’t opened after 7 days of warm compresses
• A carbuncle, or several boils at once
• A boil on the face, especially near the nose or eyes, or on the spine, groin or buttocks
• Fever or chills
• Red streaks or redness spreading from the boil
• Boils that keep coming back
• You have diabetes, a weak immune system or a heart valve problem

Get emergency care if you have a high fever, feel very unwell, or the redness and swelling are spreading fast.

Common questions about boils

What is the medical term for a boil?

Doctors call a boil a furuncle. Several boils joined together make a carbuncle, and getting boils over and over is called furunculosis. A skin abscess is a broader term for any pocket of pus under the skin, whether or not it started in a hair follicle.

Is a carbuncle worse than a boil?

Yes, usually. A carbuncle is a cluster of boils joined under the skin, so it goes deeper and drains from several openings. It is more likely to cause fever, heals more slowly and often leaves a scar. Most carbuncles need a doctor to drain them.

What does the core of a boil look like?

The core is a firm, yellow-white plug of pus and dead tissue in the center of the boil. It often comes out on its own after the boil opens, and the pain eases once it does. Don’t dig or squeeze it out, because that can spread the infection.

Can a boil make you sick?

Yes, sometimes. A boil can cause fever, chills and tiredness, especially a carbuncle. The infection can also spread into the nearby skin (cellulitis) or, rarely, the blood. See a doctor if you feel unwell, have a fever, or see redness spreading from the boil.

Questions to ask your doctor

• Does this boil need to be drained?
• Do I need an antibiotic, and is this MRSA?
• How should I care for the wound at home?
• Why do I keep getting boils, and how can I stop them?
• Should my family be treated too?

Learn more

• Boils (MedlinePlus, U.S. National Library of Medicine)
• Boils (furunculosis) (DermNet)

This guide is general information and doesn’t replace advice from your own doctor. Last updated October 2026.