Colitis is an inflammation of the large intestine (colon).

Causes, incidence, and risk factors

Colitis is an inflammation of the large intestine that is caused by many different disease processes, including acute and chronic infections, primary inflammatory disorders (ulcerative colitis, Crohn’s colitis, lymphocytic and collagenous colitis), lack of blood flow (ischemic colitis), and history of radiation to the large bowel.

For more information about a specific type of colitis see:

  • Pseudomembranous colitis  
  • Crohn’s disease (regional enteritis)  
  • Ulcerative colitis  
  • Ischemic colitis  
  • Necrotizing enterocolitis  
  • Cryptosporidium enterocolitis  
  • CMV colitis (a viral infection of the colon)


Symptoms can include abdominal pain, diarrhea, dehydration, abdominal bloating, increased intestinal gas, and bloody stools.

Signs and tests

Colitis may be identified by flexible sigmoidoscopy or colonoscopy - in both of these tests, a flexible tube is inserted in the rectum, and specific areas of the colon are evaluated. Biopsies taken during these tests may show changes related to inflammation.

Other studies that can identify colitis include:

  • Barium enema  
  • Abdominal CT scan  
  • Abdominal MRI  
  • Abdominal x-ray


Treatment is directed at the underlying cause of disease, whether it be infection, inflammation, lack of blood flow, or another cause.

See particular conditions listed above for specific recommendations.

Expectations (prognosis)

The prognosis varies with each disease state, and thus depends upon the underlying disease.


Colitis may result in bleeding, ulceration, perforation (a hole in the colon), or toxic megacolon.

Calling your health care provider

Call your health care provider if you have symptoms like abdominal pain, abdominal distention, or blood in the stool.


Prevention depends upon the underlying cause of colitis. See the specific condition.

Johns Hopkins patient information

Last revised: December 4, 2012
by Amalia K. Gagarina, M.S., R.D.

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