What is the difference between ulcerative colitis and Crohn's disease?

Dr. Lisa Ganjhu, DO

Both are inflammatory conditions of the digestive tract. Ulcerative colitis is limited to the colon and Crohn's disease can involve anywhere from the mouth to the colon.

Crohn's disease (CD) differs from ulcerative colitis (UC) in the following ways:

  • CD usually starts in the ileum (small bowel) and can spread to any part of the gastrointestinal tract. UC usually starts in the rectum and moves towards the small bowel but only affects the colon.
  • CD forms fistulas, UC does not.
  • UC only involves the mucosa and submucosa and forms ulcers in the bowel but CD can affect the entire bowel thickness, thus causing fistulas.

CD and UC are both inflammatory bowel diseases (IBD). 


Ulcerative colitis is the inflammation of the innermost lining of the large intestine and/or rectum. Crohn's disease is the inflammation of the lining and walls of the large and/or small intestine. It may also affect other parts of the digestive system and can spread deep into the tissue.

Traditionally, these two conditions were thought to be distinct types of inflammatory bowel disease (IBD). However, IBD researchers are beginning to think of IBD as a spectrum (or range) of diseases that affect the intestines.

Thus, some people may only have symptoms of ulcerative colitis or symptoms of Crohn's disease, while others may have symptoms of both conditions (known as "indeterminate colitis").

Dr. William C. Lewis, MD
Colorectal Surgeon

Ulcerative Colitis and Crohn’s Disease are different. In this video, W. Cannon Lewis, MD, of Methodist Stone Oak Hospital explains the difference between the two IBD conditions, including the location of the inflammation.

Continue Learning about Ulcerative Colitis

Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.