Abscesses occur when an area of tissue becomes infected and the body's immune system tries to fight and contain it. White blood cells (WBCs) move through the walls of the blood vessels into the area of the infection and collect in the damaged tissue. During this process, pus forms. Pus is the buildup of fluid, living and dead white blood cells, dead tissue, and bacteria or other foreign substances.

Abscesses can form in almost any part of the body. The skin, under the skin, and the teeth are the most common sites. Abscesses may be caused by bacteria, parasites, and foreign substances.

Abscesses in the skin are easy to see. They are red, raised, and painful. Abscesses in other areas of the body may not be seen, but they may cause organ damage.

Some types and locations of abscesses include:

• Abdominal abscess
• Amebic liver abscess
• Anorectal abscess
• Bartholin gland abscess
• Brain abscess
• Epidural abscess
• Peritonsillar abscess
• Pyogenic liver abscess
• Spinal cord abscess
• Subcutaneous (skin) abscess
• Tooth abscess

The health care provider will perform a physical exam, focusing on the symptoms of the abscess.

Tests to locate the abscess include:

• Ultrasound
• CT scan
• MRI scan
• X-ray (mainly for tooth abscess)

Often, a sample of fluid will be taken from the abscess and tested to see what type of germ is causing the problem.

Treatment varies, but often surgery is needed to drain the abscess. Antibiotics can also be used.

Contact your provider if you think that you have any type of abscess. Contact your dentist if you think that you have a tooth abscess.

Preventing abscesses depends on where they develop. For example, good hygiene can help prevent skin abscesses. Dental hygiene and routine care will prevent tooth abscesses.

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De Prisco G, Celinski S, Spak CW. Abdominal abscesses and gastrointestinal fistulas. In: Feldman M, Friedman LS, Brandt LJ, eds. Sleisenger and Fordtran's Gastrointestinal and Liver Disease. 11th ed. Philadelphia, PA: Elsevier; 2021:chap 29.

Gea-Banacloche JC, Tunkel AR. Brain abscess. In: Bennett JE, Dolin R, Blaser MJ, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 9th ed. Philadelphia, PA: Elsevier; 2020:chap 90.

Updated by: Jatin M. Vyas, MD, PhD, Associate Professor in Medicine, Harvard Medical School; Associate in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital, Boston, MA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.