Causes - Abscess - Overview

Most abscesses are caused by a bacterial infection.

Your immune system fights the bacteria with white blood cells. When this happens, some nearby tissue dies. This creates a hole that fills with pus to form an abscess. The pus contains a mixture of dead tissue, white blood cells and bacteria.

The abscess may get larger and much more painful as the infection continues and more pus is produced.

Some types of bacteria (staphylococcal bacteria) produce a toxin that kills white blood cells. This means the body makes more cells to keep fighting the infection. This can lead to repeated skin infections.

In rare cases, a virus, fungus or parasite may cause an abscess.

Skin abscesses

When bacteria gets under the surface of your skin, an abscess can form.

This can happen anywhere on the body.

But skin abscesses tend to be more common in the:

• underarms
• hands and feet
• chest
• abdomen
• pelvis
• back
• genitals
• buttocks

Bacteria can get into your skin and cause an abscess if you have a minor skin wound. For example, through a small cut or graze.

Bacteria can also get into your skin if a sebaceous gland (oil gland) or sweat gland becomes blocked.

Internal abscesses

Internal abscesses often develop as a complication of an existing condition.

For example, abscesses inside the tummy (abdomen) may be caused by an infection in tissue deeper in the body.

Internal abscesses can happen as a result of:

• an injury
• abdominal surgery
• an infection spreading from a nearby area

There are many ways an infection can spread into the tummy and cause an abscess to develop.

For example, bacteria can spread into your tummy if you have:

• pneumonia
• a burst appendix
• another bacterial infection in your lungs

Increased risk

Other things that increase the chance of an abscess developing include:

• a weak immune system - this can be caused by a medical condition such as HIV or a treatment such as chemotherapy
• diabetes
• an underlying inflammatory condition, such as hidradenitis suppurativa
• being a carrier of staphylococcal bacteria

Abscesses often develop in people who are generally healthy.