* Irritable bowel syndrome (IBS), a common intestinal disorder, affects the colon and may cause recurrent abdominal cramps, bloating, constipation, and diarrhea. There is no cure, but IBS symptoms may be treated by changing eating habits, reducing stress, and making lifestyle changes. A doctor may also prescribe medications to relieve diarrhea or constipation. No one test is used to diagnose IBS, but a doctor may identify it based on symptoms, medical history, and a physical exam.