Irritable bowel syndrome (IBS) is one of the most common gastrointestinal disorders, but it is puzzling for those who have it and for the doctors who treat it. The term 'irritable' is used to describe the reaction of the muscles in the intestine, which respond to stress by abnormal contractions which may result in various combinations of the three main symptoms of IBS: pain, diarrhoea and constipation. There is no test that can show whether or not you have IBS. Nor is there any clear-cut cure for the disorder. However treatment can relieve the symptoms and, with support from your doctor, you can learn to live with it.