Ulcerative Colitis

ByAaron E. Walfish, MD, Mount Sinai Medical Center;
Rafael Antonio Ching Companioni, MD, HCA Florida Gulf Coast Hospital
Reviewed/Revised Nov 2023

Ulcerative colitis is a chronic inflammatory bowel disease in which the large intestine (colon) becomes inflamed and ulcerated (pitted or eroded), leading to flare-ups (bouts or attacks) of bloody diarrhea, abdominal cramps, and fever. The long-term risk of colon cancer is higher than in people who do not have ulcerative colitis.

  • The exact cause of this disease is not known.

  • Typical symptoms during flare-ups include abdominal cramps, an urge to move the bowels, and diarrhea (typically bloody).

  • The diagnosis is based on a sigmoidoscopy or sometimes a colonoscopy.

  • People who have had ulcerative colitis for a long time are at increased risk for colon cancer.

  • Treatment is aimed at controlling the inflammation, reducing symptoms, and replacing any lost fluids and nutrients.

(See also Overview of Inflammatory Bowel Disease (IBD).)

Ulcerative colitis may start at any age but usually begins before age 30, usually between the ages of 14 and 24. A small group of people have their first attack between the ages of 50 and 70.

Ulcerative colitis usually starts in the rectum (ulcerative proctitis). It may stay confined to the rectum or over time extend to involve the entire colon. In some people, most of the large intestine is affected at once.

Ulcerative colitis usually does not affect the full thickness of the wall of the large intestine and hardly ever affects the small intestine. The affected parts of the intestine have shallow ulcers (sores). Unlike Crohn disease, ulcerative colitis does not cause fistulas or abscesses.

The cause of ulcerative colitis is not known for certain, but heredity and an overactive immune response in the intestine seem to be contributing factors. Cigarette smoking, which seems to contribute to the development and periodic flare-ups of Crohn disease, seems to decrease the risk of ulcerative colitis. However, smoking in order to reduce the risk of ulcerative colitis is ill-advised in light of the many health problems that smoking can cause.

Symptoms of Ulcerative Colitis

The symptoms of ulcerative colitis occur in flare-ups. Sometimes, a flare-up is sudden and severe, causing violent diarrhea that typically contains mucus and blood, high fever, abdominal pain, and occasionally peritonitis (inflammation of the lining of the abdominal cavity, causing severe pain across the entire abdomen). During such flare-ups, the person is profoundly ill. More often, a flare-up begins gradually, and the person has an urgency to have a bowel movement (defecate), mild cramps in the lower abdomen, and visible blood and mucus in the stool. A flare-up can last days or weeks and can recur at any time.

When the disease is limited to the rectum and the sigmoid colon, the stool may be normal or hard and dry. However, mucus containing large numbers of red and white blood cells is discharged from the rectum during or between bowel movements. People may or may not have mild general symptoms of illness, such as fever.

If the disease extends farther up the large intestine, the stool is looser, and the person may have more than 10 bowel movements a day. Often, the person has severe abdominal cramps and distressing, painful spasms that accompany the urge to defecate. There is no relief at night. The stool may be watery or contain mucus. Frequently, the stool consists almost entirely of blood and pus. The person also may have a fever and a poor appetite and may lose weight.

Complications of ulcerative colitis

The main serious complications of ulcerative colitis include

  • Bleeding

  • Fulminant colitis (toxic colitis)

  • Colon cancer

Bleeding, the most common complication, often causes iron deficiency anemia.

Fulminant colitis (also called toxic colitis) is a particularly severe complication. In nearly 10% of people who have ulcerative colitis, a rapidly progressing first attack becomes very severe, with massive bleeding, rupture (perforation) of the colon, or widespread infection. Damage to the nerves and muscles of the bowel wall causes ileus (a condition in which the normal contractile movements of the intestinal wall temporarily stop), and thus the intestinal contents are not propelled along their way. Abdominal expansion (distention) develops.

As fulminant colitis worsens, the large intestine loses muscle tone and within days—or even hours—it starts to expand (a condition sometimes referred to as toxic megacolon). This complication may cause a high fever and abdominal pain. Sometimes there is a perforation of the large intestine and the person develops peritonitis. X-rays of the abdomen may show expansion of the bowel and the presence of gas inside the wall of the paralyzed sections of intestine.

Colon cancer starts to become more common about 7 years from when ulcerative colitis started in people with extensive colitis. The risk of colon cancer is highest when the entire large intestine is affected and increases the longer the person has had ulcerative colitis. After 20 years of disease, about 7 to 10% of people will have developed cancer, and after 35 years of disease, as many as 30% of people will have developed cancer. However, people who have both inflammatory bowel disease and inflammation of the bile ducts (primary sclerosing cholangitis) are at a higher risk of colon cancer starting from the time when the colitis is diagnosed.

Colonoscopy (examination of the large intestine using a flexible viewing tube) every 1 to 2 years is advised for people who have had ulcerative colitis for more than 8 to 10 years or who have primary sclerosing cholangitis. During colonoscopy, tissue samples are taken from areas throughout the large intestine for examination under a microscope to detect the early warning signs of cancer (dysplasia). This removal and examination of tissue is called a biopsy. In a newer type of colonoscopy called chromoendoscopy, dyes are inserted into the colon during colonoscopy to highlight cancerous (malignant) and precancerous areas and may better help doctors identify areas for biopsy.

Other complications can occur, as in Crohn disease. When ulcerative colitis causes a flare-up of gastrointestinal symptoms, people also may have the following:

When ulcerative colitis is not causing a flare-up of gastrointestinal symptoms, people still may have complications that occur entirely without relation to the bowel disease such as the following:

Although people with ulcerative colitis commonly have minor liver dysfunction, only about 1 to 3% have symptoms of liver disease, which vary from mild to severe. Severe liver disease can include inflammation of the liver (chronic active hepatitis), inflammation of the bile ducts (primary sclerosing cholangitis), which narrow and eventually close, and replacement of functional liver tissue with scar tissue (cirrhosis). Inflammation of the bile ducts may appear many years before any intestinal symptoms of ulcerative colitis. The inflammation greatly increases the risk of cancer of the bile ducts and also seems to be associated with a sharp increase in the risk of colon cancer.

Diagnosis of Ulcerative Colitis

  • Stool tests

  • Sigmoidoscopy

  • Blood tests

  • Imaging tests

Doctors suspect ulcerative colitis in a person with recurring bloody diarrhea accompanied by cramps and a strong urge to defecate, particularly if the person has other complications, such as arthritis or liver problems, and a history of similar attacks.

Doctors examine the stool to look for parasites, rule out bacterial infections, and assess inflammation.

Sigmoidoscopy (an examination of the sigmoid colon using a flexible viewing tube) confirms the diagnosis of ulcerative colitis. This procedure permits a doctor to directly observe the severity of the inflammation, take samples of mucus or stool for culture, and remove tissue samples of affected areas for examination under a microscope (called a biopsy). Even during symptom-free intervals, the intestine rarely appears entirely normal, and tissue samples removed for examination under a microscope usually show chronic inflammation. A colonoscopy is usually not necessary, but doctors may need to do a colonoscopy if the inflammation extends beyond the reach of the sigmoidoscope.

Blood tests do not confirm the diagnosis of ulcerative colitis but may reveal that the person has anemia, increased numbers of white blood cells (occurs with inflammation), a low level of the protein albumin, and an elevated erythrocyte sedimentation rate (ESR) or C-reactive protein level, which also indicate active inflammation. A doctor may also do liver tests.

X-rays of the abdomen taken after barium is given by enema (called a barium enema) may indicate the severity and extent of the disease but are not done when the disease is active, such as during a flare-up, because of the risk of causing a perforation. Other x-rays of the abdomen may also be taken.

Recurring or severe symptoms of ulcerative colitis

Doctors examine people when their typical symptoms return, but they do not always do tests. If symptoms have been more frequent or longer-lasting than usual, doctors may do sigmoidoscopy or colonoscopy and a blood count. Doctors may do other tests to look for infection or parasites.

When symptoms are severe, people are hospitalized. Doctors take x-rays to look for a dilated or perforated intestine.

Treatment of Ulcerative Colitis

  • Aminosalicylates

  • Corticosteroids

  • Immunomodulating medications

  • Biologic and related agents

  • Small-molecule agents

  • Sometimes surgery

Ulcerative colitis treatment aims to control the inflammation, reduce symptoms, and replace any lost fluids and nutrients.

Specific treatment depends on the severity of people's symptoms.

General management of ulcerative colitis

Iron supplements may offset anemia caused by ongoing blood loss in the stool.

Usually, if the large intestine is swollen, people should eat a low-fiber diet (in particular, avoiding foods such as nuts, corn hulls, raw fruits, and vegetables) to reduce injury to the inflamed lining of the large intestine. However, a high-fiber diet should be resumed once the IBD flare resolves.

A diet free of dairy products may decrease symptoms and is worth trying but does not need to be continued if no benefit is noted.

Routine health maintenance measures, particularly vaccinations and cancer screening, are important.

Did You Know...

  • During flares of ulcerative colitis, people should be restricted to a low-fiber diet to reduce injury to the inflamed lining of the large intestine. Once the flare has resolved, they may return to eating high-fiber foods.



immunomodulating medication, a biologic agent

Long-term corticosteroid treatment almost always causes side effects (see sidebar Corticosteroids: Uses and Side Effects).

Immunomodulating medications

Biologic agents

Biologic agents are medicines that are created by living organisms.

tuberculosis and hepatitis B infections.

progressive multifocal leukoencephalopathy

is another kind of biologic agent given to people who have moderate to severe ulcerative colitis that has not responded to TNF inhibitors or other immunomodulating medications or who are unable to tolerate these medications. The first dose is given by vein and then by injections under the skin every 8 weeks. Side effects include injection-site reactions (pain, redness, swelling), cold-like symptoms, chills, and headache.


Small-molecule agents

 is a medication given by mouth twice a day for adults with moderate to severe ulcerative colitis. This medication is a Janus kinase (JAK) inhibitor that is not actually a biologic agent because it is created by chemical processes rather than by living organisms. However, it shares many characteristics with biologic agents, including many of their side effects. It interferes with the communication between cells that coordinate inflammation by inhibiting an enzyme (Janus kinase, or JAK). Serious side effects include increased susceptibility to infection and pulmonary embolism (the blocking of an artery of the lung by a blood clot).

is a medication for adults with moderate to severe ulcerative colitis that is given by mouth daily. It is a Janus kinase (JAK) inhibitor. This medication increases the risk for developing serious infection, heart attack, stroke, venous thrombosis (blood clot), pulmonary embolism, and arterial thrombosis (blood clot forms).

is a medication given by mouth for adults with moderate to severe active ulcerative colitis. This medication should not be used by people who have had a heart attack, chest pain (unstable angina), stroke or mini-stroke (transient ischemic attack or TIA), or certain types of heart failure in the last 6 months. This medication also should not be taken by people who have or have had a history of certain types of an irregular or abnormal heartbeat (arrhythmia) that is not corrected by a pacemaker, by people with severe untreated sleep apnea, or by people who take a monoamine oxidase inhibitor

Severity of symptoms

People with ulcerative proctitis,

People with moderate or extensive disease

People with severe colitis

Fulminant colitis (toxic colitis)

People are monitored closely for signs of infection or a perforation. People whose condition does not improve in 24 to 48 hours need immediate surgery to remove all or most of the large intestine.

Maintenance regimens


About 30% of people with extensive ulcerative colitis require surgery. Emergency surgery may be necessary for sudden life-threatening attacks with massive bleeding, perforation, or fulminant colitis.

Sometimes surgery is needed even when there is no emergency reason for surgery. These situations include chronic colitis that is disabling or that constantly requires high doses of corticosteroids, cancer, and narrowing of the large intestine or growth retardation in children.

Complete removal of the large intestine, rectum, and anus (total proctocolectomy) permanently cures ulcerative colitis, restores life expectancy to normal, and eliminates the risk of colon cancer. However, inflammation develops in the small intestine in about 25% of people after surgery even though their small intestine was not previously affected. Because the rectum and anus are removed, people must have a permanent ileostomy. In an ileostomy, a surgeon brings the end of the lowest portion of the small intestine (ileum) out through an opening in the abdominal wall (stoma). People who have an ileostomy must always wear a plastic bag (ileostomy bag) over the opening to collect the stool that comes out. An ileostomy used to be the traditional price of this cure.

However, various alternative procedures are now available, and the most common one is a procedure called proctocolectomy with ileal pouch-anal anastomosis (IPAA). In this procedure, the large intestine and most of the rectum are removed, and a small reservoir (pouch) is created out of the small intestine and attached to the remaining rectum just above the anus. Because the muscles of the anus (anal sphincter) are not removed, this procedure allows people to remain in control of their bowels (continence). However, because a small amount of tissue of the rectum can remain, the risk of cancer is significantly decreased but not eliminated. A common complication of IPAA is inflammation of the reservoir (called pouchitis). To treat pouchitis, doctors give antibiotics. Most cases of pouchitis can be controlled with medications, but a small percentage cannot. For these cases, doctors create an ileostomy to correct the problem.

For people with ulcerative proctitis, surgery is rarely needed, and life expectancy is normal. In some people, though, the symptoms may be very difficult to treat.

Prognosis for Ulcerative Colitis

Ulcerative colitis is usually chronic, with repeated flare-ups and remissions (periods of no symptoms). In about 10% of people, an initial attack progresses rapidly and results in serious complications. Another 10% of people recover completely after a single attack. The remaining people have some degree of recurring disease.

People who have disease only in their rectum (ulcerative proctitis) have the best prognosis. Severe complications are unlikely. However, in about 20 to 30% of people, the disease eventually spreads to the large intestine (thus evolving into ulcerative colitis). In people who have ulcerative proctitis that has not spread, surgery is rarely required, cancer rates are not increased, and life expectancy is normal.

Colon cancer

The long-term survival rate for people with colon cancer caused by ulcerative colitis is about 50%. Most people survive if the diagnosis is made during the early stages and the colon is removed in time.

More Information

The following English-language resources may be useful. Please note that THE MANUAL is not responsible for the content of these resources.

  1. Crohn's and Colitis Foundation of America: General information on Crohn disease and ulcerative colitis, including access to support services

  2. National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)—Ulcerative Colitis: General information on ulcerative colitis, including information about research and clinical trials

  3. United Ostomy Associations of America (UOAA): Information and support resources for people who live with an ostomy

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