Colitis is inflammation of your colon, also known as your large intestine. If you have colitis, you’ll feel discomfort and pain in your abdomen that may be mild and reoccurring over a long period of time, or severe and appearing suddenly.

There are different types of colitis, and treatment varies depending on what type you have.

The types of colitis are categorized by what causes them.

Ulcerative colitis

Ulcerative colitis (UC) is one of two conditions classified as inflammatory bowel disease. The other is Crohn’s disease.

UC is a life-long disease that produces inflammation and bleeding ulcers within the inner lining of your large intestine. It generally begins in your rectum and spreads to your colon.

UC is the most commonly diagnosed type of colitis. It occurs when your immune system overreacts to bacteria and other substances in your digestive tract, but experts don’t know why this happens. Common types of UC include:

  • proctosigmoiditis, which affects your rectum and lower portion of your colon
  • left-sided colitis, which affects the left side of your colon beginning at the rectum
  • total colitis, which affects your entire large intestine

Pseudomembranous colitis

Pseudomembranous colitis (PC) occurs from overgrowth of the bacterium Clostridium difficile. This kind of bacteria normally lives in your intestine but doesn’t cause problems because it’s balanced by the presence of “good” bacteria. Certain medications, especially antibiotics, may destroy healthy bacteria. This allows Clostridium difficile to take over, releasing toxins that cause inflammation.

Ischemic colitis

Ischemic colitis (IC) occurs when blood flow to your colon is suddenly cut off or restricted. Blood clots can be a reason for sudden blockage. Atherosclerosis, or buildup of fatty deposits, in the blood vessels that supply your colon is usually the reason for recurrent IC.

This type of colitis is often the result of underlying conditions. These may include:

Although it’s rare, IC may occur as a side effect of taking certain medications.

Additional causes

Other causes of colitis include infection from parasites, viruses, and food poisoning from bacteria. You may also develop the condition if your large intestine has been treated with radiation.

Different risk factors are associated with each type of colitis.

You’re more at risk for UC if you:

You’re more at risk for PC if you:

You’re more at risk for IC if you:

Depending on your condition, you may experience one or more of the following symptoms:

  • abdominal pain or cramping
  • bloating in your abdomen
  • weight loss
  • diarrhea with or without blood
  • blood in your stool
  • urgent need to move your bowels
  • chills or fever
  • vomiting

Your doctor may ask about the frequency of your symptoms and when they first occurred. They’ll perform a thorough physical exam and use diagnostic tests such as:

  • colonoscopy, which involves threading a camera on a flexible tube through the anus to view your rectum and colon
  • sigmoidoscopy, which is similar to a colonoscopy but shows only your rectum and lower colon
  • stool samples
  • abdominal imaging such as MRI or CT scans
  • ultrasound, which is useful depending on the area being scanned
  • barium enema, an X-ray of your colon after it’s injected with barium, which helps make images more visible

Treatments vary by a few factors:

  • type of colitis
  • age
  • overall physical condition

Bowel rest

Limiting what you take in by mouth can be useful, especially if you have IC. Taking fluids and other nutrition intravenously may be necessary during this time.


Your doctor may prescribe anti-inflammatory medication to treat swelling and pain, and antibiotics to treat infection. Your doctor may also treat you with pain medications or antispasmodic drugs.


Surgery to remove part or all of your colon or rectum may be necessary if other treatments don’t work.

Your outlook depends on the type of colitis you have. UC may require lifelong medication therapy unless you have surgery. Other types, such as IC, may improve without surgery. PC generally responds well to antibiotics but may recur.

In all cases, early detection is critical to recovery. Early detection may help prevent other serious complications. Let your doctor know about any symptoms you’re experiencing.