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Understanding Colitis

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Colitis is when a part of your colon becomes inflamed or swollen. The colon is also called the large intestine. It helps with digestion and waste removal.

Outline of abdomen showing small intestine and colon.


What causes colitis?

Colitis can be caused by many things. The most common causes are:

  • Viral or bacterial infections.

  • Inflammatory bowel disease (ulcerative colitis or Crohn’s disease).

  • Certain medicines, such as antibiotics.

  • Radiation therapy to the colon.


Symptoms of colitis

The symptoms of colitis may last a short time. Or they can be chronic. The most common symptoms are:

  • Diarrhea, sometimes bloody.

  • Stomach pain or cramping.

  • Fever.

  • Weight loss in severe cases.


Diagnosing colitis

Your doctor will take a full health history and family history. They will also give you a physical exam. Depending on the results of your history and physical exam, your doctor may also order certain tests to help find out the cause of your colitis. These may include:

  • Lab tests. Your blood and stool will be checked.

  • Endoscopy and biopsy.  Endoscopy is a procedure that uses a long, flexible tube with a tiny light and camera on 1 end. It checks the inside of your large intestine. Two types of endoscopy are sigmoidoscopy (to view the lower colon) and colonoscopy (to view the entire colon). During an endoscopy, your doctor may take a small sample of your tissue to look at under a microscope. This is called a biopsy.

  • Imaging tests. These include X-ray, CT scan, MRI, and capsule endoscopy.


Treatment for colitis

Treatment for colitis depends on what is causing it and how serious your symptoms are. In some cases, you may not need treatment. For example, colitis from an infection may go away without care. 

Treatment may include: 

  • Medicines. You may take these by mouth (oral) or as a rectal suppository or enema. Some medicines are given by injection. They can reduce swelling and ease symptoms.

  • Changes in your diet. Some foods can make symptoms worse. Common triggers are milk, coffee, alcohol, and fried foods. Talk with your doctor to develop a healthy diet plan.

  • Surgery. In some cases, you may need surgery to remove a damaged part of the colon.


Call 911

Call 911 if:

  • You have trouble breathing.

  • You have confusion.

  • You are very drowsy or have trouble waking up.

  • You faint or lose consciousness.

  • You have a rapid heart rate.

  • You have chest pain.


When to contact your doctor 

Contact your doctor right away if:

  • Your symptoms don’t get better, or get worse.

  • You have a fever of 100.4°F (38°C) or higher, or as directed by your doctor.

  • You have pain that gets worse.

  • You have bloody diarrhea.

  • You have bleeding from your rectum.

  • You have new symptoms.

Author: Semko, Laura

© 2000-2026 The StayWell Company, LLC. All rights reserved. This information is not intended as a substitute for professional medical care. Always follow your healthcare professional's instructions.
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