Microscopic Colitis

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Definition & Facts

Microscopic colitis is a chronic inflammatory bowel disease (IBD) in which abnormal reactions of the immune system cause inflammation of the inner lining of your colon. Anyone can develop microscopic colitis, but the disease is more common in older adults and in women.

Health care professional using a microscope.

Symptoms & Causes

The most common symptom of microscopic colitis is chronic diarrhea. Experts aren’t sure what causes microscopic colitis but think genes and abnormal immune reactions play a role. Certain medicines and smoking increase the risk for the disease.


To help diagnose microscopic colitis, your doctor may order medical tests to check for signs of conditions that cause symptoms similar to those of microscopic colitis. Doctors order a colonoscopy with biopsies to diagnose microscopic colitis.


To treat microscopic colitis, your doctor may recommend changing the medicines you take, changing your diet, quitting smoking, and taking medicines to help manage symptoms. Medicines may improve symptoms and help bring on and maintain remission.

Eating, Diet, & Nutrition

In some cases, doctors may recommend changing your diet to help reduce diarrhea symptoms in microscopic colitis. Talk with your doctor about what type of diet is right for you.

Clinical Trials

The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) and other components of the National Institutes of Health (NIH) conduct and support research into many diseases and conditions.

Related Conditions & Diseases

Related Diagnostic Tests

Your Digestive System & How It Works

The digestive system is made up of the gastrointestinal (GI) tract—also called the digestive tract—and the liver, pancreas, and the gallbladder. The GI tract is a series of hollow organs joined in a long, twisting tube from the mouth to the anus.

Related Research

Last Reviewed April 2021

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.

The NIDDK would like to thank:
Adam S. Cheifetz, M.D., Beth Israel Deaconess Medical Center, and Kristin E. Burke, M.D., M.P.H., Massachusetts General Hospital