An ulcer is a sore on the skin or mucous membrane, which forms the top layers of the skin or tissue. It can occur in the mouth, stomach, and other parts of the body. When ulcers occur in the lining of the upper part of the gastrointestinal (GI) tract, it is known as gastric ulcers and if ulcer are formed in the first part of the small intestine, then it is referred as duodenal or peptic ulcer. Moreover, ulcerative colitis is a form of inflammatory bowel disease (IBD), which is a disease of the colon (largest portion of the large intestine). Constant diarrhea mixed with blood is the most common symptom of developing ulcerative colitis.