Irritable bowel syndrome (IBS) is a common intestinal condition characterized by abdominal pain and cramps; changes in bowel movements (diarrhea, constipation, or both); gassiness; bloating; nausea; and other symptoms. There is no cure for IBS. Much about the condition remains unknown or poorly understood; however, dietary changes, drugs, and psychological treatment are often able to eliminate or substantially cureduce its symptoms.

IBS was once called—among other things—colitis, spastic colon, nervous colon, and spastic bowel. Some of these names reflected the now outdated belief that IBS is a purely psychological disorder, a product of the patient's imagination. Although modern medicine recognizes that stress can trigger IBS attacks, medical specialists agree that IBS is a genuine physical disorder--or group of disorders--with specific identifiable characteristics.

The symptoms of IBS tend to rise and fall in intensity rather than growing steadily worse over time...