What Is Ulcerative Colitis?

Ulcerative colitis (UC) is a disease that affects your large intestine, or colon. It causes irritation and swelling called inflammation. Eventually that leads to sores called ulcers in the lining there.

UC is a type of inflammatory bowel disease, but it’s different from other diseases with similar symptoms, like Crohn’s disease or irritable bowel syndrome. There’s no cure yet, and people usually have symptom flare-ups off and on for life. The right treatments can help you keep a handle on the disease, though.


Ulcerative colitis happens when your immune system makes a mistake. Normally it attacks invaders in your body, like the common cold. But when you have UC, your immune system thinks food, good gut bacteria, and the cells that line your colon are the intruders. White blood cells that usually protect you work against the lining of your colon instead. They cause the inflammation and ulcers.

Doctors aren’t sure why people get the condition. Your genes may play a role -- the disease sometimes runs in families. Other things in your environment may make a difference, too. So far, research hasn’t discovered one clear cause for UC.

Other things, like food and stress, don’t cause it, but they can trigger a flare of symptoms.


The main symptom of ulcerative colitis is bloody diarrhea. There might be some pus in your stools, too.

Other problems include:

  • Crampy belly pain
  • Sudden urges to empty your colon right away
  • Not feeling hungry
  • Weight loss
  • Feeling tired
  • Fever
  • Dehydration
  • Joint pain or soreness
  • Canker sores
  • Eye pain when you look at a bright light
  • Too few red blood cells, called anemia
  • Skin sores
  • Feeling like you haven’t completely emptied your colon after you use the bathroom
  • Waking up at night to go
  • Not being able to hold your stools in

Your symptoms can flare up, go away, and then come back again. Sometimes they might not bother you for weeks or years at a time.

Other gut diseases can have some of the same symptoms. Crohn’s disease causes inflammation, too, but it happens in other places in your digestive tract. Ulcerative colitis affects only your large intestine and only the inside lining. Irritable bowel syndrome has some of the same symptoms as UC, but it doesn’t cause inflammation or ulcers. Instead, it’s a problem with the muscle in your intestines.



Your doctor will use different tests to tell if you have UC instead of another gut disease.

Blood tests can show if you have anemia or an infection.

Stool sample tests can help your doctor rule out an infection or parasite in your colon. They can also show if there is blood in your stool that you can’t see.

Flexible sigmoidoscopy lets a doctor look at the lower part of your colon. He will put a bendable tube into your lower colon through your bottom. The tube has a small light and camera on the end. Your doctor might also use a small tool to take a piece of the lining of your lower colon. This is called a biopsy. A specialist will look at the sample under a microscope.

Colonoscopy is the same process as flexible sigmoidoscopy, only your doctor will look at your whole colon, not just the lower part. He may spray a blue dye inside your colon during a colonoscopy. This is called chromoendoscopy, and it lets him see which parts are affected by UC.

X-rays are less common for diagnosing the disease, but your doctor may want you to have one in special cases.


UC treatment has two main goals. The first is to ease your symptoms and give your colon a chance to heal. The second is to prevent more flare-ups. You may need a mix of diet changes, medication, or surgery to reach those goals.

Diet. Food doesn’t cause ulcerative colitis, but some types can make your symptoms worse. You might find that soft, bland food doesn’t bother you as much as spicy or high-fiber dishes. If you can’t digest the sugar in milk called lactose (meaning you’re lactose intolerant), your doctor may tell you to avoid dairy products. To make sure you get enough vitamins and nutrients from your meals and snacks, your doctor may recommend a high-protein, high-calorie eating plan that is low in fiber.

Medicine. Your doctor may prescribe a few different kinds of drugs, including:

  • Antibiotics to fight infections and let your large intestine heal
  • Medicine to lower inflammation in your colon and control your symptoms. You may start by taking one type, called aminosalicylates. If those don’t work or your symptoms are more severe, your doctor may prescribe another type of anti-inflammatory drug, a corticosteroid.
  • Meds to help stop your immune system’s attack on your colon
  • Biologics are drugs made from proteins in living cells instead of chemicals. They are for people with very severe ulcerative colitis.

Surgery. If other treatments don’t work or your UC is severe, you might need surgery to remove your colon (colectomy).

WebMD Medical Reference Reviewed by Jennifer Robinson, MD on February 04, 2016



National Institute of Diabetes and Digestive and Kidney Diseases. “Ulcerative Colitis.”

Cleveland Clinic. “Ulcerative Colitis.”

Crohn’s & Colitis Foundation of America. “What is Ulcerative Colitis?” “Colitis Diagnosis & Testing,” “Colitis Treatment Options.”

American College of Gastroenterology. “Ulcerative Colitis.”

© 2016 WebMD, LLC. All rights reserved.