Irritable bowel syndrome is the most common functional GI disorder. The patient experiences recurrent abdominal pain along with abnormal defecation in the absence of any structural abnormality of the gut. The Rome-lll diagnostic criteria for IBS is very important as there is no laboratory test for this GI disorder. It is as follows: ~ Recurrent abdominal pain for >3 days per month over the last 3 months PLUS 2 or more of the following: 1. Improvement with defecation 2. Onset associated with a change in frequency of stool 3. Onset associated with a change in form (appearance) of stool