A carbuncle is when multiple boils (or furuncles form close together. It occurs because hair follicles next to each other become infected, causing pus-filled lumps that may converge into one larger lump.
It is usually caused by bacteria known as Staphylococcus aureus, which is normally found on the skin or inside the nostrils in some people. It tends to cause no harm, although it can cause an infection, such as a boil, if it gets under the skin.
Boils, or furuncles, look like red lumps that are painful and initially quite hard but, over the course of four to seven days, get softer as the amount of pus inside increases. The pus or infection can join together between each boil to become a carbuncle. You may see it progress to a white or yellow head on the lump. The skin around the boils may also become red and sore. The pus may come out of the boils on their own or be reabsorbed by the body.
Once the pus is released, it can take around four to five days for the boil to heal, but it may leave a scar. The advice is not to try and burst the boil yourself, as it is not usually done cleanly and may lead to re-infection.
While boils are quite common in male teenagers and young adults, carbuncles are mainly seen in middle-aged and elderly men, and you are more likely to develop them if you have diabetes or have a lowered immune system. They can be painful, especially as the amount of pus trapped inside increases. They are usually found in places on the body that are hairy while also being warm and moist, such as the neck or on the back. These conditions allow the bacteria to flourish, and any friction may cause small breaks in the skin, allowing the bacteria to get in.
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The bacteria from the carbuncle can spread to other people, so it is important to try not to touch the area, but if you do then wash your hands thoroughly before and after. Do not share clothes or towels, and avoid swimming while you have a carbuncle.
Soak a washcloth in hot water (but not boiling – make sure it is not hot enough that it could burn your skin) and apply it to the area around four times a day. This can help draw the pus to the skin's surface and help speed up the healing process. Magnesium sulfate paste also works in a similar way by drawing out the pus. It should also help relieve some of the pain. You can take over-the-counter pain relievers such as acetaminophen. Keep the area clean, and wash your towels and clothes regularly.
You should see your doctor if you have a carbuncle. See your doctor urgently or call 911 if you also feel unwell (such as a fever) or if the redness around the carbuncle is rapidly increasing or tracking across your body.
Your doctor will ask you about your symptoms, your medical history, and any relevant family medical history. They will then examine the area and discuss with you the next course of action. For a carbuncle, the doctor may make a small incision and drain the pus out. They will then clean the area and apply a dressing in order to keep the area clean while it heals. Your doctor may consider prescribing medications such as antibiotics.
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