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What is an abscess?

An abscess is a collection of pus inside your body. Abscesses usually form because of an infection or because a foreign object becomes trapped in your body. When your body fights an infection or tries to destroy a foreign object trapped inside, white blood cells fill the affected tissues, and the resulting fluid is called pus.

Pus contains living and dead bacteria, living and dead white blood cells, and the remnants of the cells and tissue that were killed or injured by the infection or by your body’s immune response.

Abscesses often form in or near the skin or in the mouth near the teeth. An abscess often looks like a bump of any size that is red and often swollen, and inside of the bump is a pus-filled space. It is unwise to attempt to drain any abscess—no matter how superficial. Doing so could lead to a lethal blood-borne infection (sepsis).

Abscesses are usually treatable with antibiotics, surgery, or a combination of these. In many cases, surgical drainage of an abscess is required. A specimen of the fluid within the abscess is generally sent to the laboratory to identify any causative bacteria. Most abscesses can be treated effectively and have fairly few complications, though some abscesses can occur deeper in your body or in your organs and can cause much more serious damage.

Seek prompt medical care if you suspect you have an abscess, or if you are being treated for an abscess and the condition persists or causes you concern.


What other symptoms might occur with an abscess?

An abscess may accompany other symptoms, which will vary depending on the underlying disease, disorder or condition.

Skin symptoms that may occur along with an abscess

An abscess may accompany other symptoms affecting the skin including:

  • Oozing or drainage of a fluid from the skin
  • Pain on or around a lump
  • Peeling or ulcerating skin
  • Redness, warmth or swelling

Other symptoms that may occur along with an abscess

An abscess may accompany symptoms related to other body systems. Such symptoms include:

Serious symptoms that might indicate a life-threatening condition

In some cases, an abscess may be a symptom of a life-threatening condition that should be immediately evaluated in an emergency setting. Seek immediate medical care (call 911) if you, or someone you are with, have any of these life-threatening symptoms:


What causes an abscess?

An abscess is caused by your immune system responding to some type of infection or foreign object. Bacterial infections are the most common cause of an abscess, especially an abscess of the skin or mouth. Parasites can cause abscess formation in your organs and, though rare, this can be a serious medical condition. A foreign object lodged inside you, such as a bullet, can also cause an abscess.

Common causes of an abscess

An abscess may be caused by a variety of common conditions including:

  • Foreign object trapped inside you, such as a thorn or piece of metal that breaks off in your skin; also, retained foreign body fragments after previous attempted removal

  • Infected diverticulum in the large intestine can cause a diverticular abscess

  • Infection at the site of previous surgery (perioperative wound contamination)

  • Skin infection may result in an abscess

  • Tooth infection may progress to a periodontic abscess

  • Wound or trauma to the skin, especially a puncture wound, may cause an abscess

Rarer causes of an abscess

An abscess can also be caused by rare infections including:

  • Infection by microorganisms like amoeba can cause abscess formation in your liver

  • Infection by certain parasites can cause a variety of abscesses in your body’s organs

  • Infection in your brain can cause a cerebral abscess

Questions for diagnosing the cause of an abscess

To diagnose your condition, your doctor or licensed health care practitioner will ask you several questions related to your abscess including:

  • When did you first notice the abscess?

  • Have you had any other symptoms along with the abscess?

  • Are you taking any medications?

  • Have you wounded or injured your skin in the area around the abscess recently?

What are the potential complications of an abscess?

The complications of an abscess vary widely depending on the cause and location. A small skin abscess treated promptly usually does not result in any permanent complications other than a small scar. However, a large abscess or an abscess in an organ can affect underlying tissue or organ function and may possibly cause serious and permanent damage.

Because an abscess can be due to serious diseases, failure to seek treatment can result in serious complications and permanent damage. Once the underlying cause is diagnosed, it is important for you to follow the treatment plan that you and your health care professional design specifically for you to reduce the risk of potential complications including:

  • Brain or spinal cord injury

  • Liver damage

  • Nerve damage resulting in weakness or tingling

  • Paralysis

  • Sepsis (widespread infection) or localized spread of infection

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Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2018 Nov 12
  1. Abscess. Medline Plus, a service of the National Library of Medicine National Institutes of Health. http://www.nlm.nih.gov/medlineplus/ency/article/001353.htm
  2. Peritonsillar abscess: What you should know. Am Family Physician. 2008 Jan 15;77(2):209. http://www.aafp.org/afp/2008/0115/p209.html
  3. Collins RD. Differential Diagnosis in Primary Care, 5th ed. Philadelphia: Lippincott, Williams & Williams, 2012.
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