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Signs & Symptoms of Inflamed Colon

author image Dr. C. Richard Patterson
C. Richard Patterson is a retired surgeon and chief medical officer with special interest and experience in gastrointestinal, breast, cancer and trauma surgery. He is the author or co-author of 17 scientific publications, including textbook chapters.
Signs & Symptoms of Inflamed Colon
Inflammation of the colon often causes abdominal pain. Photo Credit Jupiterimages/Photos.com/Getty Images

An inflamed colon, or colitis, may arise from a variety of causes, including infections, antibiotics or reduced blood flow to the colon. But as all causes affect the large intestine, some signs and symptoms tend to be shared by many people with colitis. Diarrhea and abdominal pain are typical symptoms of an inflamed colon. Other signs and symptoms related to the colon or even more distant areas of the body may occur as well. If you think you may have colitis, see your doctor. Accurate diagnosis and appropriate therapy are necessary to help prevent worsening of symptoms or possible complications.


Diarrhea, occurring as either soft stools or excessively frequent stools, is one of the most common symptoms of colitis. The colon usually absorbs much of the water that enters the intestines, leading to well-formed solid bowel movements. When the colon is inflamed, its absorbing ability is reduced and the stool becomes soft or watery. The greater water content also means that there is a greater volume of stool. This or the inflammation itself can stimulate more frequent bowel movements.

Watery stool is particularly common with antibiotic-associated colitis. This condition is caused by antibiotics destroying normal bacteria in the colon, which allows harmful bacteria to grow. Clostridium difficile is the most common bacteria producing symptoms in this type of colitis. Dehydration can occur if water lost in the stool is not replaced by increasing the amount of fluids consumed.

Diarrhea may be minimal or absent if the colitis affects only the very last part of the colon, as most of the water will have already been absorbed before the stool reaches the inflamed region.

Abdominal Pain

Abdominal pain is another feature of colitis. It is typically a cramping pain that occurs as intermittent spasms. This pain may be caused by inflammation stimulating contractions of the muscles within the wall of the colon. The location of the pain can sometimes give a clue to the part of the colon that is inflamed. Pain on the left side of the abdomen often means that the last part of the colon is affected. Colitis due to reduced blood flow to the colon -- ischemic colitis -- most commonly affects this area of the colon, producing left-sided pain. Ulcerative colitis also generally causes left abdominal pain.

Sometimes the abdominal pain is more constant. This may occur if the inflammation extends to involve the tissues surrounding the colon. If the inflammation is severe enough to cause a hole in the colon wall, stool contents can spill into the abdominal cavity, causing a serious infection called peritonitis. This potentially life-threatening complication produces constant severe pain that can eventually spread to the entire abdomen.

Other Colon-Related Effects

Abdominal bloating is common, as the increased volume of stool in the intestines causes the intestines to expand. When colitis is severe, the intestines can become so enlarged that they weaken and a hole forms in the intestinal wall. Another symptom of colitis can be bleeding, which usually appears as blood mixed with the stool, but it may also appear as blood alone coming from the rectum. Bleeding occurs because of damage to the lining of the colon due to inflammation. It can lead to anemia -- reduced red blood cells in the body -- that may range from mild to severe, depending on the amount of blood that is lost.

Mucus may also be visible in the stool, especially with ulcerative colitis. Colitis involving the last part of the colon and adjacent rectum may cause cramping of the rectum. This cramping, known as tenesmus, produces an urge to have a bowel movement, even if a person has just had one.

Distant Signs and Symptoms

Fever accompanies many types of colitis. It is often mild but if the colitis is severe enough to produce peritonitis, the fever can be high. Peritonitis is particularly likely to occur with ischemic colitis. It occurs in about 15 to 20 percent of people with ischemic colitis, according to a review article in the July 2009 issue of "Cleveland Clinic Journal of Medicine."

Weight loss, loss of appetite, low energy and fatigue are other symptoms that may occur with colitis. Ulcerative colitis may also produce inflammation of other body areas, such as the joints, spine, liver or parts of the eye.

Warnings and Precautions

See your doctor if you have diarrhea, especially if it is severe, worsening or persists for more than a few days. Also see your doctor if you notice any of the other symptoms that may be found with colitis, especially if they occur together. Seek prompt medical attention if you have a high fever, severe abdominal pain or bloating, or notice a significant amount of blood coming from your rectum -- either alone or mixed with stool. Obtain immediate medical help if you have lightheadedness, dizziness or fainting, as these could indicate severe dehydration, significant blood loss or peritonitis.

Reviewed and revised by: Mary D. Daley, M.D.

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