Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) is a functional gastrointestinal (GI) disorder. Symptoms include crampy abdominal pain, bloating, constipation, and/or diarrhea. The severity of symptoms varies from mildly annoying to debilitating. 

In a person with IBS, the muscles in the colon (part of the large intestine) that move digested food along are exceptionally sensitive to certain stimuli or triggers. IBS is diagnosed based on symptoms (especially chronic abdominal pain and altered bowel habits) and an evaluation of the GI tract to rule out other diagnoses. 

The causes of IBS aren’t well understood, and it’s often managed with a combination of diet and lifestyle modifications and medications. IBS is a chronic condition that can be controlled, but not cured.

Frequently Asked Questions

  • What causes IBS?

    The causes of IBS are complex and somewhat unknown. There may be an interplay between pain sensitivity, gut motility problems, low-grade inflammation, and gut bacteria and hormones dysfunction in brain and gut communication. IBS sometimes develops after an infection in your digestive tract or after trauma. It also tends to run in families, and research suggests that gene mutations play a role.

  • How is IBS treated?

    Doctors may recommend dietary (fiber, low-FODMAP diet) and other lifestyle changes (exercise, sleep) and therapies. There are also over-the-counter (OTC) and prescription medications that can be used to target symptoms of diarrhea, constipation, or pain. Therapies can include cognitive behavioral therapy, gut-directed hypnotherapy, and relaxation training.

  • How is IBS diagnosed?

    IBS is a diagnosis of exclusion. Your doctor will run blood and fecal occult tests and ask about your family and personal medical history. After ruling out infections and other digestive diseases, you may be diagnosed with one of three types of IBS based on symptoms:

  • What should I eat if I have IBS?

    Eating smaller, more frequent meals and gradually increasing fiber, especially soluble fiber (nuts, beans, fruit), can help improve symptoms in IBS. Your doctor may suggest temporarily avoiding fatty foods and other common triggers or following a low-FODMAP diet, which eliminates hard-to-digest carbohydrates for six to eight weeks and then slowly reintroduces them.

Key Terms

Page Sources
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  3. Deloughery TG. Iron deficiency anemia. Med Clin North Am. 2017;101(2):319-332. doi:10.1016/j.mcna.2016.09.004

  4. Salem A, Roland BC. Small intestinal bacterial overgrowth (SIBO). J Gastroint Dig Syst. 2014;4:225. doi:10.4172/2161-069X.1000225

Additional Reading