Irritable bowel syndrome (IBS) is a functional disorder of the large intestine with no evidence of accompanying structural defect. IBS is characterized by some combination of abdominal pain or distension; altered bowel function, constipation, or diarrhea; hypersecretion of colonic mucus; dyspeptic symptoms (flatulence, nausea, anorexia); and varying degrees of anxiety or depression. If you have symptoms suggestive of IBS, please consult a physician for an accurate diagnosis.