Ulcerative colitis is a type of inflammatory bowel disease (IBD) that affects the lining of the colon (large intestine). Ulcerative colitis is known as an inflammatory disease because it causes inflammation, sores, bleeding, and scarring of the inner walls of the colon. The inflammation almost always affects the rectum and lower part of the colon. The inflammation involves continuous areas of the wall rather than small patches.

Ulcerative colitis affects more than 104,000 people in Canada. Ulcerative colitis can affect people of any age, but it is usually diagnosed when people are between 15 and 25 years old or between 45 and 55 years old. It can seriously decrease your quality of life.

Ulcerative colitis is an unpredictable condition that has relapses (attacks of symptoms or flare-ups) followed by periods of remission, when symptoms go away. There's no telling when a flare-up may strike. For example, about 30% of people in remission in a given year will have a flare-up the next year.

During a flare-up, you may experience bloody diarrhea, stomach cramps, and weight loss. You may be unable to perform your usual activities and may even end up in the hospital. Severe attacks of ulcerative colitis can be life-threatening.

Ulcerative colitis can also increase the risk of colorectal cancer. People with ulcerative colitis should have regular colonoscopies to screen for cancer, as recommended by their doctors. A colonoscopy is a test where a flexible tube is inserted through the rectum into the colon to check for cancer.

Ulcerative colitis can be cured by surgery to remove part or all of the colon. About 25% to 30% of people with severe ulcerative colitis eventually need surgery. After surgery, you may need to wear a bag outside the body to collect solid waste, which is emptied 3 or 4 times a day. This can affect your lifestyle and quality of life, and it can take a while to adjust to living with these changes.

Instead of wearing a bag, some individuals may choose a procedure that involves the creation of a "pelvic pouch" from existing tissue that is inserted into the pelvis to collect waste inside the body. The involved portion of the intestine is attached to the anus, allowing normal bowel movements to occur. In some types of surgery with internal pouches, the pouch is connected to the outside of the body via a leak-resistant valve, where you eliminate the waste by learning over a toilet and inserting a small tube through the valve.

Ulcerative colitis can affect your ability to work, but less so than Crohn's disease. About 90% of people diagnosed with ulcerative colitis are fully able to work after the first year after diagnosis, compared with 75% of people with Crohn's disease.

If you think you may have ulcerative colitis, talk to your doctor.