What causes an abscess?

What is an abscess?

An abscess is a pocket of pus that forms in the body when the immune system tries to fight an infection. It can develop in the skin, gums, teeth, or deeper tissues. Abscesses are often swollen, painful, and warm to the touch.

The pus is made up of dead white blood cells, bacteria, and tissue debris. This usually means the body is dealing with an infection that has become trapped in one area. If an abscess is not treated, it may get larger or spread.

Infection is the main cause

The most common cause of an abscess is a bacterial infection. Bacteria can enter the body through a cut, bite, blocked pore, or another break in the skin. Once inside, they can multiply and trigger inflammation.

The body sends white blood cells to the area to fight the infection. When the infection is difficult to clear, pus builds up and creates an abscess. This is why abscesses often form where bacteria have been able to settle and grow.

Common causes on the skin

Skin abscesses often start with a small injury or infection. A boil, ingrown hair, infected scratch, or infected wound can all lead to one. They may also develop around hair follicles or sweat glands.

People with conditions such as acne or eczema may be more likely to get skin abscesses. Broken or irritated skin can make it easier for bacteria to enter. Poor hygiene, close contact with infected people, or shared personal items can also raise the risk.

Dental and gum infections

Abscesses are also common in the mouth. A tooth abscess can happen when bacteria reach the inside of a tooth, often through tooth decay, a crack, or dental injury. Gum disease can also allow infection to build up around the teeth.

These abscesses can cause severe pain, swelling, and sensitivity. Because the infection is trapped in a confined area, it may not go away on its own. Dental abscesses need prompt treatment from a dentist.

Factors that increase the risk

Some people are more likely to develop abscesses than others. Diabetes, a weakened immune system, smoking, and poor circulation can all make infections more likely or harder to fight. Repeated skin friction or blocked glands can also contribute.

Living with an existing skin condition or having had an abscess before may increase the chance of another one. In some cases, a strain of bacteria such as Staphylococcus aureus is involved. This is one reason abscesses can sometimes keep coming back.

When to seek medical help

It is important to get advice if an abscess is painful, growing, or not improving. You should also seek help if you have a fever, feel unwell, or the redness is spreading. Abscesses on the face, near the eye, or in the groin may need urgent assessment.

Never try to squeeze or burst an abscess yourself. This can push the infection deeper or spread it to other areas. A GP, urgent care service, or dentist can advise on the right treatment.