Irritable Bowel Syndrome


Irritable bowel syndrome, a condition marked by diarrhea, constipation and abdominal pain, is caused by excessive spasms of the large intestine. (It is also known as spastic colon, nervous bowel, irritable colon and mucous colitis.) Irritable bowel syndrome is not considered a disease as such because there are no organic abnormalities or physical changes. In many people, however, stress or feelings of anxiety, guilt or resentment seem to trigger the symptoms, It is probably the most common abdominal complaint brought to the attention of doctors, affecting one-third to one-half of all patients who seek relief from gastrointestinal problems. In addition, many people have irritable bowel syndrome without ever consulting their doctors about it.


The condition appears in late adolescence or early adulthood. For unknown reasons, women are affected about twice as often as men.


The abdominal discomfort of an irritable bowel ranges from sharp, cramping-like pains to a continuous, dull ache. It is often relieved by a bowel movement. The lower left part of the abdomen may be tender to the touch. This abdominal pain usually appears after eating, although no particular food or type of food can be identified as the cause.


There is also usually diarrhea, sometimes alternating with constipation. The diarrhea typically occurs immediately after a meal or when getting up in the morning, and there is often mucus in the stool. In addition, there may be other, less definite symptoms, such as fatigue, anxiety and difficulty in concentrating.


These symptoms may last for a few days or weeks and then cease for months at a time. Also, they may recur with varying degrees of intensity, over a long period.


After nutrients have been digested and absorbed in the small intestine, the waste material is propelled into the large intestine (also called the colon or bowel) for eventual elimination as a bowel movement. Under normal circumstances, regular muscular contractions (intestinal motility) move this waste matter along the five-foot length of the colon and into the rectum. When the irritable bowel syndrome is present, however, the pattern of motility becomes disordered by excessive muscular contractions, which cause the pain, diarrhea and constipation.


It is not known what causes the overactivity of the intestinal muscle. Emotional stress is believed to be a factor in a great many cases. Some researchers think that the syndrome is an allergic response to particular foods. There also is some evidence that alcohol, caffeine and heavy smoking may worsen the problem.