The course of ulcerative colitis varies greatly from one person to another. Some people may have only mild symptoms, and others may have severe symptoms or complications that, in unusual cases, may be life-threatening.

Ulcerative colitis may be mild , moderate or severe. It may be described as dependent on cortiosteriods, unresponsive to steroids, or not active (in remission).

this also may be defined by the part of the large intestine affected: the rectum (proctitis), the left side of the colon (left-sided colitis), or the entire colon (pancolitis). One out of every two adults with ulcerative colitis has proctitis. Pancolitis is the most common form of ulcerative colitis in children, affecting about half.

Most people with ulcerative colitis have periods of remission that may last up to several years. These periods are interrupted by occasional flare-ups of moderate symptoms. Between 5% and 10% of people have symptoms all the time.1