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KEY POINTS
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A boil is an infected lump under your skin that is raised, red, painful, and filled with pus. Pus is a thick fluid that usually contains white blood cells, dead tissue, and germs such as bacteria or fungus. A carbuncle is a single area of infection formed from a group of boils that develop close together due to spreading infection.
Boils commonly develop because bacteria get into hair follicles, which are the small openings in your skin from which hair grows. Bacteria normally live on the skin, particularly on certain parts of the body, such as the nose, mouth, genitals, and rectum. The bacteria can cause an infection if they enter the skin through a scrape, irritation, or injury of some kind. Sometimes friction on the skin, from clothing for example, will cause a hair follicle to swell up. This can make the opening swell closed, trapping the bacteria inside and starting an infection.
Boils and carbuncles often form in moist areas of the body such as the back of the neck, buttocks, thighs, groin, and armpits. They also form where there are skin folds, such as the abdomen.
Boils and carbuncles are more common and may be harder to treat in people who have diabetes or poor circulation, and in people whose immune systems are weakened by HIV, cancer, or other health problems. The tendency to have boils can also run in families.
Symptoms may include:
You may have swollen lymph nodes in the area of the boil, especially near your neck, armpit, or groin area. The lymph system is part of your body's system for fighting infection. The lymph system consists of lymph nodes that store blood cells (lymphocytes) to fight infection and vessels that carry fluid, nutrients, and wastes between your body and your bloodstream.
Your healthcare provider will ask about your symptoms and medical history and examine you.
If you have boils often, you may have lab tests of your blood or urine. These tests can check for conditions such as diabetes, kidney disease, or liver disease that might make you more likely to have the boils.
A boil can sometimes be treated at home, but a carbuncle often needs medical treatment.
For treatment at home, you can:
These steps will help relieve the pain, reduce the risk of spreading the infection, and help boils to heal.
Sometimes your healthcare provider will need to drain the boil. To do this, your healthcare provider will clean the skin over the boil and may inject medicine to make it numb. Your provider will use a needle or cut the skin over the boil and drain it. Draining the pus often decreases the pain right away because it relieves the pressure. Your healthcare provider may pack the pocket with gauze, and leave some gauze sticking out through the cut in your skin. This lets any pus that forms in the boil drain out. The gauze packing is changed every day or two until the boil heals.
If a boil doesn’t yet have a point or head on it, your provider may prescribe an antibiotic to see if it will get rid of the boil without draining or opening of the boil.
In most cases, a boil will not heal until it opens and drains. The time it takes for a boil or carbuncle to heal depends on how big it is and what other health problems you have. Most boils or carbuncles heal in 1 to 3 weeks.
Follow the full course of treatment prescribed by your healthcare provider. Take pain or antibiotic medicine exactly as prescribed by your healthcare provider. If you are given an antibiotic, take it for as long as your healthcare provider prescribes, even if you feel better. If you stop taking the medicine too soon, you may not kill all of the bacteria and the infection may come back.
Ask your healthcare provider:
Make sure you know when you should come back for a checkup.
To help prevent boils and carbuncles from spreading and coming back: