Ulcerative Colitis

View or Print All Sections

Definition & Facts

Ulcerative colitis is a chronic inflammatory bowel disease (IBD) in which abnormal reactions of the immune system cause inflammation and ulcers on the inner lining of your large intestine. Ulcerative colitis can develop at any age, but the disease is more likely to develop in people between the ages of 15 and 30.

Man Holding his stomach in pain.

Symptoms & Causes

Symptoms of ulcerative colitis vary from person to person and may include diarrhea, passing blood with your stool, and abdominal pain. Experts aren’t sure what causes ulcerative colitis but think genes, abnormal immune reactions, the microbiome, and the environment play a role.


To diagnose ulcerative colitis, doctors review your symptoms and medical and family history and perform a physical exam and tests. Medical tests may include blood tests, stool tests, and endoscopy of the large intestine.


Doctors typically treat ulcerative colitis with medicines to reduce inflammation in the large intestine and help bring on and maintain remission. In some cases, doctors may recommend surgery to treat ulcerative colitis or complications.

Eating, Diet, & Nutrition

Ulcerative colitis symptoms may cause some people to lose their appetite and eat less, and they may not get enough nutrients. If you have ulcerative colitis, you should eat a healthy, well-balanced diet.

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 September 2020

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 Cheifetz, M.D., Beth Israel Deaconess Medical Center