Definition & Facts of Ulcerative Colitis

What is ulcerative colitis?

Ulcerative colitis is a chronic disease in which abnormal reactions of the immune system cause inflammation and ulcers on the inner lining of your large intestine.

Ulcerative colitis can begin gradually and become worse over time. However, it can also start suddenly. Symptoms can range from mild to severe. In between periods of flares—times when people have symptoms—most people have periods of remission—times when symptoms disappear. Periods of remission can last for weeks or years. The goal of treatment is to keep people in remission long term.

Does ulcerative colitis have another name?

Ulcerative colitis is an inflammatory bowel disease (IBD). Crohn’s disease and microscopic colitis are other common types of IBD.

How common is ulcerative colitis?

Research suggests that about 600,000 to 900,000 people in the United States have ulcerative colitis.1,2

Who is more likely to have ulcerative colitis?

Ulcerative colitis is more likely to develop in people

  • between the ages of 15 and 30, although the disease may develop in people of any age3
  • who have a first-degree relative—a parent, sibling, or child—with IBD
  • of Jewish descent4
Mother and daughter talking.
People who have a first-degree relative with IBD are more likely to have ulcerative colitis.

What are the complications of ulcerative colitis?

Ulcerative colitis may lead to complications that develop over time, such as

  • anemia, a condition in which you have fewer red blood cells than normal. Ulcerative colitis may lead to more than one type of anemia, including iron-deficiency anemia and anemia of inflammation or chronic disease.
  • bone problems, because ulcerative colitis and corticosteroids used to treat the disease can affect the bones. Bone problems include low bone mass, such as osteopenia or osteoporosis.
  • problems with growth and development in children, such as gaining less weight than normal, slowed growth, short stature, or delayed puberty.
  • colorectal cancer, because patients with long-standing ulcerative colitis that involves a third or more of the colon are at increased risk and require closer screening.

In some cases, ulcerative colitis may lead to serious complications that develop quickly and can be life-threatening. These complications require treatment at a hospital or emergency surgery. Serious complications include

  • fulminant ulcerative colitis, which causes extremely severe symptoms, such as more than 10 bloody bowel movements in a day, often with fever, rapid heart rate, and severe anemia.3,4 People with fulminant ulcerative colitis have a higher chance of developing other complications, such as toxic megacolon and perforation.
  • perforation, or a hole in the wall of the large intestine.
  • severe rectal bleeding, or passing a lot of blood from the rectum. In some cases, people with ulcerative colitis may have severe or heavy rectal bleeding that may require emergency surgery.
  • toxic megacolon, which occurs when inflammation spreads to the deep tissue layers of the large intestine, and the large intestine swells and stops working.

Severe ulcerative colitis or serious complications may lead to additional problems, such as severe anemia and dehydration. These problems may require treatment at a hospital with blood transfusions or intravenous (IV) fluids and electrolytes.

Health problems affecting other parts of the body

Some people with ulcerative colitis also have inflammation in parts of the body other than the large intestine, including the

People with ulcerative colitis also have a higher risk of blood clots in their blood vessels.

Colorectal cancer

Ulcerative colitis increases the chance of getting colorectal cancer. People have a higher risk for developing colorectal cancer if ulcerative colitis affects more of their large intestine, is more severe, started at a younger age, or has been present for a longer time. People with ulcerative colitis also have a higher risk of developing colorectal cancer if they have primary sclerosing cholangitis or have a family history of colorectal cancer.3

If you have ulcerative colitis, your doctor may recommend a colonoscopy to screen for colorectal cancer. Screening is testing for diseases when you have no symptoms. Screening can check for dysplasia—precancerous cells—or colorectal cancer. Diagnosing cancer early can improve chances for recovery.

For people with ulcerative colitis, doctors typically recommend colonoscopies every 1 to 3 years, starting 8 years after ulcerative colitis started.3 For people with ulcerative colitis and primary biliary cholangitis, doctors typically recommend colonoscopies every year, starting at diagnosis.3


Last Reviewed September 2020
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This content is provided as a service of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), part of the National Institutes of Health. NIDDK translates and disseminates research findings to increase knowledge and understanding about health and disease among patients, health professionals, and the public. Content produced by NIDDK is carefully reviewed by NIDDK scientists and other experts.