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Dr Karen Martin
Reviewed by Dr Karen MartinReviewed on 19.10.2023 | 3 minutes read

A boil, known medically as a furuncle, is when a hair follicle becomes infected, causing a pus-filled lump. It is usually caused by bacteria called Staphylococcus aureus, which are often found on the skin or inside the nostrils, and usually cause no harm. However, if there is a break in the skin, the bacteria can get in and cause an infection that leads to a boil.

A boil is a red lump that is painful and initially quite hard but, over the course of about four to seven days, gets softer as the amount of pus inside increases. You may see it progress to have a white or yellow head on the lump. The skin around the boil may also become red and sore.

In a few cases, multiple boils can occur in the same area, known as a carbuncle. The pus may come out of the boil on its 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 and may leave a scar. The advice is not to try and burst the boil yourself.

Most small boils go away on their own without the need for treatment. They can be painful, especially as the amount of pus in the boil increases. They are usually found in places on the body that are warm and moist or where skin rubs against skin or clothes in areas such as the armpits, groin, butt, neck, or face. This is because bacteria like warm moist environments, and any friction may cause breaks in the skin, allowing bacteria to get in.

Boils are more common in teenagers or young adult males, those with a lowered immune system or diabetes, if you are overweight, or already have a skin problem that may then make you itch or scratch your skin.

Is it contagious?

The bacteria from the boil can spread to other people, so it is important to try not to touch the area, but if you do, wash your hands thoroughly before and after. Do not share clothes or towels, and avoid swimming while you have a boil.

Healthwords pharmacists' top tips

Soak a cloth 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 the boil four times a day. This can help draw the pus to the skin's surface and helps 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 also take over-the-counter pain relievers such as acetaminophen. Keep the area clean, and wash your towels and clothes regularly.

When should I see my doctor?

You should see your doctor if it's not improving after a week if it's a large boil or you have multiple, if the boil is on your face, if your child has a boil, or if you have a lowered immune system or suffer from diabetes. See your doctor urgently or call 911 if you have a boil and also feel unwell or feverish, or if the redness around the boil is rapidly spreading.

What will my doctor do?

The doctor will ask you about your symptoms and your medical history. They will examine the area and discuss with you the next course of action. For small boils, the doctor will likely ask you to keep the area clean and monitor it as it heals on its own. The doctor may make a small incision and drain the pus out for large boils. They will then clean the area and apply a dressing in order to keep the area clean while it heals. In a few cases, your doctor may prescribe medications such as antibiotics.

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This article has been written by UK-based doctors and pharmacists, so some advice may not apply to US users and some suggested treatments may not be available. For more information, please see our T&Cs.
Dr Karen Martin
Reviewed by Dr Karen Martin
Reviewed on 19.10.2023
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