Irritable Bowel Syndrome (IBS) | Causes & Risk Factors


What causes IBS?

Doctors describe IBS as a “functional gastrointestinal disorder.” This means that it is caused by changes in how the gastrointestinal (digestive) system works, but no one knows exactly what causes these changes to occur. Most doctors and researchers believe that IBS is caused by a combination of health problems. Possible health problems that may cause or worsen IBS include:

  • Problems with the nerve signals from your brain to your intestine
  • Problems with how your intestines push food through your system
  • Mental health problems, such as depression, anxiety, and panic disorders
  • An infection in your stomach or intestines
  • An overgrowth of bacteria in the intestines
  • Changes in hormone levels or other body chemicals
  • Undiagnosed food sensitivities or allergies


See a list of resources used in the development of this information.

Written by editorial staff

Reviewed/Updated: 08/12
Created: 12/96