An abscess is a tender, soft, swelling filled with pus, often surrounded by an area of skin coloured from pink to deep red.
An abscess can be painful and warm to touch, and can appear anywhere on your body. The most common sites are in your armpits (axillae), areas around your anus and vagina (Bartholin's abscess), the base of your spine (pilonidal abscess), around a tooth ( dental abscess), and in your groin. Inflammation around a hair follicle can also lead to the formation of an abscess, which is called a boil (furuncle).
Abscess image: Scott Camazine/Photo Researchers Inc
Unlike other infections, antibiotics alone will not usually cure an abscess. Generally, an abscess must be opened and the pus drained out in order for it to improve. Sometimes draining occurs on its own if the pocket of pus breaks through the skin, but often it is necessary for a doctor to carry out a procedure called incision and drainage.
Abscesses are caused by obstruction of oil-producing (sebaceous) glands or sweat glands, inflammation of hair follicles, or from minor breaks and punctures of the skin. Germs (bacteria) get under the skin or into these glands, which causes an inflammatory response as your body's defences try to kill the bacteria.
As they develop, the middle of the abscess liquefies and contains dead cells, bacteria, and other debris. This area begins to grow, creating tension under the skin and further inflammation of the surrounding tissues. Pressure and inflammation cause the pain and surrounding redness of the skin.
People with weakened immune systems get certain abscesses more often. This is because the body has a decreased ability to ward off infections. Those with any of the following are at risk of having more severe abscesses.
As an abscess develops, it becomes a painful, soft, swelling that is red, warm to touch, and tender.
As some abscesses progress, they may "point" and come to a head - so you can see the pus inside - and then spontaneously discharge (rupture).
- Most abscesses will continue to get worse without care. The infection can spread to the tissues under the skin and even into the bloodstream.
- If the infection spreads into deeper tissue, you may develop a fever and begin to feel ill.
When to seek medical care
Seek medical advice if any of the following occur with an abscess:
- You have an abscess larger than 1 cm or a half-inch across.
- The affected area continues to enlarge or becomes more painful.
- You have an underlying condition such as AIDS, cancer, diabetes, leukaemia, sickle cell disease or have poor circulation.
- You are an IV drug abuser.
- You are receiving steroid therapy or chemotherapy.
- The abscess is on or near your rectal or groin area.
- You have a fever of 38.5°C/101.5°F or higher.
- You have a red streak going away from the abscess, or with tender lymph nodes (lumps) in an area anywhere between the abscess and your chest area - for example, an abscess on your leg can cause swollen lymph nodes in your groin area.