Pronunciation: /ˈæbsɛs/ · Part of speech: noun · Plural: abscesses · Field: general medicine / surgery

Definition. An abscess is a painful, swollen area where pus forms — a localised collection of pus that builds up within the tissues of the body. It typically develops as the body’s response to infection, as in the examples “She had an abscess under a tooth” or when “the doctor decided to lance the abscess.”

How it forms. An abscess usually arises when bacteria (or sometimes other organisms) invade the tissue and the body mounts a defensive response. White blood cells travel to the site to fight the infection, and the resulting mixture of dead white cells, bacteria, and damaged tissue forms pus. The body walls off this collection within a cavity to contain the infection. As pus accumulates, pressure builds, producing the characteristic pain, swelling, redness, and warmth. As the dictionary note states, the formation of an abscess is often accompanied by a high temperature (fever), reflecting the body’s systemic response to infection.

Common sites. Abscesses can develop almost anywhere in the body. Familiar examples include:

• Skin abscesses (boils), in the skin and underlying tissue.
• Dental abscesses, around the root of a tooth or in the gum.
• Internal abscesses, in organs such as the liver, lung, or brain, or within body cavities, which are more serious and harder to detect.

Acute versus chronic. As the comment explains, the type of abscess guides treatment:

• An acute abscess develops quickly and, once enough pus has formed, is generally dealt with by incision and drainage — opening it to let the pus out (sometimes described as lancing the abscess).
• A chronic abscess develops more slowly and is usually treated with drugs, such as antibiotics, although drainage may still be needed.

Clinical relevance. Draining the pus is often the key step in treating an abscess, because antibiotics alone may not penetrate well into a walled-off collection. Antibiotics are used in addition when infection is spreading or in certain locations. Internal abscesses may require imaging to locate them and specialised drainage procedures. An untreated abscess can enlarge, spread infection to surrounding tissue or the bloodstream, and become dangerous, so medical assessment is important — and an abscess should not be squeezed or opened without proper care.

Distinction from related terms. A cyst is a closed sac that may contain fluid but is not necessarily infected or full of pus. Cellulitis is a spreading infection of the skin and soft tissue without a walled-off pus collection. A boil (furuncle) is a specific type of skin abscess centred on a hair follicle. An empyema is a collection of pus within an existing body cavity. An abscess is specifically a localised, walled-off collection of pus.

Etymology. From Latin abscessus, “a going away” (ab- = away + cedere = to go) — reflecting the old idea that the diseased matter “departed” from the body and gathered at one site.

⚠️ Disclaimer: This explanation is provided for general educational and informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Do not attempt to open or drain an abscess yourself. Always consult a qualified healthcare professional regarding any clinical questions.