Irritable bowel syndrome (IBS) is a range of symptoms that happen at the same time. Belly pain, cramping, gas, bloating, and changes in bowel habits are the most common issues. Pain from IBS is often better after a bowel movement.

The Intestines
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Causes of IBS

IBS is a functional disorder that affects the intestines. The exact cause is unknown. Nerves, muscles, air, and movement all help the intestines work smoothly. One or more problems in any of these pathways can lead to IBS. Increased sensitivity in your intestines can be influenced by:

  • Infection or inflammation
  • Changes in the normal bacteria of the intestines—may lead to more gas production
  • Certain foods
  • Stress, anxiety, or depression
  • Missing enzymes that breakdown certain sugars—present from birth (rare)

Types of IBS

IBS types are based on the bowel habit that is causing the most problems:

  • IBS with diarrhea
  • IBS with constipation
  • Mixed type
  • Unclassified—do not fit into other types of IBS
What are the risk factors for irritable bowel syndrome?What are the symptoms of irritable bowel syndrome?How is irritable bowel syndrome diagnosed?What are the treatments for irritable bowel syndrome?Are there screening tests for irritable bowel syndrome?How can I reduce my risk of irritable bowel syndrome?What questions should I ask my doctor?What is it like to live with irritable bowel syndrome?Where can I get more information about irritable bowel syndrome?

Revision Information

  • Reviewer: EBSCO Medical Review Board Daus Mahnke, MD
  • Review Date: 12/2018 -
  • Update Date: 06/07/2019 -