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JAMA Patient Page
October 5, 2011

Irritable Bowel Syndrome

JAMA. 2011;306(13):1501. doi:10.1001/jama.306.13.1501

Irritable bowel syndrome (IBS) affects the gastrointestinal (GI) tract, especially the colon (the large bowel). Irritable bowel syndrome causes diarrhea and sometimes constipation (difficulty with bowel movements). Approximately 20% of persons in the developed world have IBS symptoms at some time in their lives. Irritable bowel syndrome is generally diagnosed when more serious problems like inflammatory bowel disease (Crohn disease and ulcerative colitis), celiac disease, infection with parasites, cancer, or malabsorption (bowel does not absorb nutrients properly) have been looked for and not found. Women are more likelythan men to have IBS. People who have continuous or recurring diarrhea, constipation, or both are often referred to a gastroenterologist, a doctor with specialized education in the management of digestive diseases, including bowel problems. Irritable bowel syndrome is called a functional disorder because there is no known physical cause for its signs and symptoms. It is important to seek medical attention if you have episodes of diarrhea or constipation on a regular basis, have a change in your bowel habits, or experience bloody stools because these may be signs of serious medical issues, such as colon or rectal cancer or inflammatory bowel disease.

Signs and symptoms of ibs

  • Diarrhea

  • Constipation

  • Watery stools (which may also include mucus)

  • Abdominal pain and cramping

  • Bloating

  • Gas

Diagnosis and testing

  • Medical history questions focus on bowel habits, diet, exercise, and stress. Physical examination looks for other causes of GI problems, as well as other body system diseases.

  • Complete blood count and blood chemistries may be ordered to look for anemia and other abnormalities such as an allergy to gluten.

  • Testing for blood in the stool.

  • Endoscopy of the GI tract may include a colonoscopy (using a lighted flexible instrument to look at the inner surface of the colon) and an esophagogastroduodenoscopy, which looks at the inner surface of the esophagus, the stomach, and the duodenum (first part of the small intestine). Biopsies (samples of tissue sent to the laboratory) may be taken to exclude the possibility of cancer, celiac disease, or inflammatory bowel disease.

  • Other tests may be done, including x-ray tests of the GI tract to look for causes of diarrhea or constipation and computed tomography (CT) for persistent abdominal pain.


  • Change your diet by removing foods that make IBS symptoms worse. Irritable bowel syndrome is often made worse by large meals, high-fat meals, alcohol, chocolate, or caffeinated drinks. Eating smaller, more frequent meals may make IBS symptoms better.

  • Lactose intolerance happens when some adults and children eat or drink dairy products, but this is different from IBS.

  • Stress reduction may help IBS management.

  • Regular exercise may help reduce IBS symptoms.

  • Treatment of anxiety and depression, if they are also present, may help with IBS symptoms.

  • Medications used to treat IBS symptoms include fiber supplements, antispasmodic medication (reducing the movement within the colon to ease pain and bloating), antidiarrheal medications, or laxatives for constipation.

For more information

Inform yourself

To find this and previous JAMA Patient Pages, go to the Patient Page Index on JAMA 's Web site at www.jama.com. Many are available in English and Spanish. A Patient Page on dyspepsia was published in the April 5, 2006, issue; one on celiac disease was published in the September 16, 2009, issue; one on colon cancer was published in the December 17, 2008, issue; one on colonoscopy was published in the March 16, 2011, issue; and one on Crohn disease was published in the April 9, 2008, issue.

Sources: National Institute of Diabetes and Digestive and Kidney Diseases, American Gastroenterological Association

The JAMA Patient Page is a public service of JAMA. The information and recommendations appearing on this page are appropriate in most instances, but they are not a substitute for medical diagnosis. For specific information concerning your personal medical condition, JAMA suggests that you consult your physician. This page may be photocopied noncommercially by physicians and other health care professionals to share with patients. To purchase bulk reprints, call 312/464-0776.