Irritable bowel syndrome (IBS) is a functional disorder in which the bowel does not function properly causing abdominal discomfort or pain, cramping, gas, bloating, diarrhea, and/or constipation among other symptoms. IBS involves the colon or large bowel, the part of the digestive tract that stores stool. While there is no cure, there are effective treatments for this disorder.
Experts are not certain what causes IBS. They believe it is a disorder of the muscles and/or nerves of the bowel: nerves may have a hyper response when the bowel stretches with food, or muscles may over-contract in response to food, causing cramping and diarrhea while or after eating.
IBS usually starts before age 35 years, but can begin at any age. Nearly three-quarters of patients with IBS are women and the syndrome appears to run in families.
IBS is diagnosed by assessing symptoms and ruling out other conditions such as polyps, inflammation, food intolerance or allergies, and celiac disease.
Doctors will perform a physical examination, blood tests, and an x-ray of the bowel. A colonoscopy also will be performed. This involves insertion of a thin, flexible tube quipped with a light and camera into the anus to view the bowel. Additional tests may check for bowel motility (how fast food passes through) and if the anal muscles are functioning properly.
IBS most commonly causes abdominal pain or discomfort, often relieved by or associated with a bowel movement. Other symptoms include chronic and painful constipation and/or diarrhea, gas, heartburn, discomfort in the upper stomach region, feeling uncomfortably full or nauseous after eating a meal, a white-colored mucus in stool, a swollen or bloated abdomen, and the sensation that a bowel movement is unfinished. Women with IBS often notice a change of symptoms around their menstrual cycles.
Treatment usually involves medication, dietary changes, stress management, and exercise. Medications include laxatives, antidiarrheals, antispasmodics, low-dose antidepressants, alosetron, and lubiprostone. Alosetron blocks the action of the hormone serotonin on the colon to help slow the movement of waste and relieve feelings of pain and urgency in patients with IBS. Lubiprostone increases fluid secretion in the intestines to help stool to pass more easily in patients with constipation caused by IBS.
Avoid foods that worsen IBS, including fatty foods, milk products, alcohol, chocolate, carbonated drinks, sorbitol, and caffeine. Add foods with fiber to your diet gradually, eat smaller meals, and drink 6 to 8 glasses of water each day.
Stress management through yoga, exercise, and counseling also can reduce symptoms, and exercise also can help the bowel function better.