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 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
Most boils are caused by Staphylococcus aureus, a type of bacteria commonly found on the skin and inside the nose. Boils sometimes develop at sites where the skin has been broken by a small injury or an insect bite, which gives the bacteria easy entry.
Although anyone — including otherwise healthy people — can develop boils or carbuncles, the following factors can increase your risk:
- Close contact with a person who has a staph infection.
- Other skin conditions. Because they damage your skin’s protective barrier, skin problems, such as acne and eczema, make you more susceptible to boils and carbuncles.
- Compromised immunity.
Treatments and drugs
You can generally treat small boils at home by applying warm compresses to relieve pain and promote natural drainage.
For larger boils and carbuncles, treatment may include:
- Incision and drainage. Your doctor may drain a large boil or carbuncle by making a small incision in the tip. Deep infections that can’t be completely drained may be packed with sterile gauze to help soak up and remove additional pus.
- Sometimes your doctor may prescribe antibiotics to help heal severe or recurrent infections.
Lifestyle and home remedies
For small boils, these measures may help the infection heal more quickly and prevent it from spreading:
- Warm compresses.
- Never squeeze or lance a boil yourself. This can spread the infection.
- Prevent contamination. Wash your hands thoroughly after treating a boil.
Although it’s not always possible to prevent boils, especially if you have a compromised immune system, the following measures may help you avoid staph infections:
- Wash your hands regularly with mild soap.
- Keep wounds covered.
- Keep personal items personal. Avoid sharing personal items, such as towels, sheets, razors, clothing and athletic equipment.