What is Ulcerative Colitis?

Ulcerative colitis affects just the large intestine and rectum. That’s where inflammation and ulcers develop. The inflammation prevents water from being reabsorbed into the bloodstream. The result is diarrhea.


If you have ulcerative colitis, you may have:

  • Diarrhea (frequently bloody)
  • Stomach pain and cramping
  • Urgent need to go to the bathroom

Inflammation and ulceration cause bleeding, which is why there is often blood mixed in with the diarrhea. You also may experience nausea, fatigue, weight loss, and loss of appetite. As with Crohn’s disease, symptoms vary—largely depending on the part of the large intestine that is involved. Unlike Crohn’s disease, which has clear (disease-free) sections of the colon (also called “skipped” sections), ulcerative colitis moves in a continuous way along the colon—with no skipped areas.


Ulcerative colitis that involves only the rectum is called proctitis. If the disease affects the left side of the colon, it is referred to as leftsided colitis. If it involves the entire colon, it is called pancolitis.