Of course, the best-known symptom of ulcerative colitis is the associated diarrhea. This is what makes it all too easy to associate with IBS. Here, the body is trying to rid itself of the discomfort and irritation in the colon and so it will begin contractions to force out the stool.
This can also be very painful, and you might find that when you eat, you almost immediately feel yourself needing to empty your bowels. This can make eating different foods a stressful experience and you might find yourself needing to rapidly run for the toilet.
If you repeatedly experience diarrhea, then there are a number of different potential causes, including IBS, and ulcerative colitis.