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Inflammation of the colon causes the muscle layers to go into intermittent spasm and cause cramp-like pain, which is pain that comes and goes. The pain usually is in the lower abdomen. Since the muscles fail to contract in a normal pattern and the colonic contents move through the colon rapidly, there is little opportunity for water to be reabsorbed. This leads to watery diarrhea. If the lining of the colon is inflamed and breaks down, bleeding may occur.

With colitis, particularly colitis involving the distal colon (rectum and sigmoid colon), the pain often crescendos and precedes a diarrheal bowel movement. After the bowel movement, the pain may relent but then returns with the next episode of pain.

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