What is Irritable Bowel Syndrome (IBS)?

If you have a bloated belly are constantly loosening your belt and always dashing to the loo, you might have irritable bowel syndrome (IBS). IBS is the commonest bowel disorder. It is a problem of the bowel (intestines), the long tube that connects the stomach with the anus. The anus is the opening where bowel movements pass from the body. With IBS food does not move through the bowel normally. The normal gut moves contents along the gut through muscular contractions (propulsion), but also has areas of hold up (segmentation). The combination of propulsion and segmentation is called peristalsis, and when it is working normally, one is completely unaware of it. The control of peristalsis is complex and the best way to regard irritable bowel is as a loss of co-ordination of these muscular contractions.

It is known as a "functional" disorder, meaning that it is a recognized group of symptoms relating to the bowel and its function without any evidence of disease when the colon is examined. In people with IBS, the nerve endings lining the colon are thought to be more sensitive than normal to contractions of the bowel and to the passage of gas and fluid, causing pain and cramping. In addition, the nerves that control the muscles in the gut overreact to stimuli like the passage of food following a meal. This causes painful spasms and contractions that inappropriately speed or slow the passage of stool through the colon, resulting in diarrhoea or constipation.

IBS is not an organic disease like inflammatory bowel disease or cancer, where structural changes do occur; and IBS does not lead to such diseases or otherwise cause permanent damage. Nor is IBS an emotional or personality disorder, although stress, anxiety, and depression can trigger flare-ups of IBS symptoms or be caused by them.

IBS is more common in people under 35 years. Women get IBS much more than men. You may have it on and off during your lifetime. But sometimes symptoms go away as you get older. IBS cannot be cured but it can be controlled.
There are some old-fashioned names for irritable bowel syndrome in common usage including irritable colon, spastic colon and mucous colitis. These are misleading since the condition not only affects the colon, but also the remainder of the gut.