A skin abscess often appears as a swollen, pus-filled lump under the surface of the skin. You may also have other symptoms of an infection, such as a high temperature (fever) and chills.
It's more difficult to identify an abscess inside the body, but signs include:
Read more about the symptoms of an abscess.
See your GP if you think you may have an abscess. They can examine a skin abscess or refer you to hospital if you may have an internal abscess.
There are several tests available to help diagnose an abscess, depending on where it's located.
Read about diagnosing an abscess.
Most abscesses are caused by a bacterial infection.
When bacteria enter your body, your immune system sends infection-fighting white blood cells to the affected area.
As the white blood cells attack the bacteria, some nearby tissue dies, creating a hole which then fills with pus to form an abscess. The pus contains a mixture of dead tissue, white blood cells and bacteria.
Internal abscesses often develop as a complication of an existing condition, such as an infection elsewhere in your body. For example, if your appendix bursts as a result of appendicitis, bacteria can spread inside your tummy (abdomen) and cause an abscess to form.
Read about the causes of abscesses.
A small skin abscess may drain naturally, or simply shrink, dry up and disappear without any treatment.
However, larger abscesses may need to be treated with antibiotics to clear the infection, and the pus may need to be drained. This will usually be done either by inserting a needle through your skin or by making a small incision in the skin over the abscess.
Read more about treating an abscess.
Most skin abscesses are caused by bacteria getting into a minor wound, the root of a hair or a blocked oil or sweat gland.
Ensuring that your skin is clean, healthy and largely free of bacteria can help reduce the risk of skin abscesses developing.
You can reduce the risk of bacteria spreading by:
Don't squeeze the pus out of the abscess yourself, because this can easily spread the bacteria to other areas of your skin. If you use tissues to wipe any pus away from your abscess, dispose of them straight away to avoid germs spreading. Wash your hands after you've disposed of the tissues.
Take care when shaving your face, legs, underarm areas or bikini area to avoid nicking your skin. Clean any wounds immediately and visit your GP or local NHS walk-in centre if you think there may be something trapped in your skin. Don't share razors or toothbrushes.
Read more about looking after your skin.
It may also help to reduce your risk of skin abscesses by:
It's difficult to prevent internal abscesses, as they're often complications of other conditions.
There are many other types of abscess not fully covered here, including: