Functional Gastrointestinal Disorders

Irritable Bowel Syndrome

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.


Because IBS is a functional disorder, the colon looks normal. IBS is a clinical diagnosis (based on symptoms). However, since other digestive disorders may also cause some IBS symptoms, NewYork-Presbyterian doctors may perform certain tests to rule out other causes depending on your specific presentation. These tests may include:

  • Physical examination
  • Blood and urine tests
  • Examination of the stool
  • Colonoscopy (insertion of a flexible scope to see inside the colon)
  • Upper Endoscopy (insertion of a flexible scope to see inside the esophagus, stomach and small intestine)
  • Abdominal imaging tests, such as x-rays and ultrasound
  • Breath tests for malabsorption or bacterial overgrowth
  • Specific motility tests for different parts of the GI tract


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.

Treating IBS

Your gastroenterologist and a registered dietitian can help you identify treatments that relieve your IBS symptoms.

  • Irritable bowel syndrome diet. We may ask you to keep a food diary to identify foods that make your IBS symptoms worse. You may also find it helpful to eat smaller meals, drink six to eight glasses of water each day, and avoid certain foods (such as fatty foods, milk products, alcohol, chocolate, carbonated drinks, and caffeine). Your dietitian will work with you one-on-one to tailor a diet that works best for you as sometimes certain foods can trigger symptoms of IBS. Other patients might respond well to certain diets like the low FODMAP diet.
  • Reducing stress. Many people with IBS find that activities aimed at lowering stress—such as yoga, exercise, and counseling—contribute to reducing their IBS symptoms. Exercise can help the bowel function better while also reducing stress. NewYork-Presbyterian offers stress management and lifestyle optimization services through our Integrative Health and Well-being program. Our therapies can help to promote relaxation, reduce stress and anxiety, and relieve your symptoms.
  • Medications. Your doctor may recommend laxatives to treat constipation, anti-diarrheal medications to treat diarrhea, and anti-spasmodic drugs to help control spasms and pain in the colon. Low doses of certain antidepressants can also contribute to reducing pain in some people. Several medications are now approved by the Food and Drug Administration for both IBS with constipation and IBS with diarrhea. Your doctor can explain how they work and help you choose which medication might be helpful for you.

Contact Us

Division of Digestive & Liver Disease

NewYork-Presbyterian/Columbia University Irving Medical Center

Gastroenterology & Hepatology

NewYork-Presbyterian/Weill Cornell Medical Center