Symptoms & Causes of Irritable Bowel Syndrome

What are the symptoms of IBS?

The most common symptoms of irritable bowel syndrome (IBS) are pain in your abdomen, often related to your bowel movements, and changes in your bowel movements. These changes may be diarrhea, constipation, or both, depending on what type of IBS you have.

Other symptoms of IBS may include

  • bloating
  • the feeling that you haven’t finished a bowel movement
  • whitish mucus in your stool

Women with IBS often have more symptoms during their periods.

IBS can be painful but doesn’t lead to other health problems or damage your digestive tract.

To diagnose IBS, you doctor will look for a certain pattern in your symptoms over time. IBS is a chronic disorder, meaning it lasts a long time, often years. However, the symptoms may come and go.

What causes IBS?

Doctors aren’t sure what causes IBS. Experts think that a combination of problems may lead to IBS. Different factors may cause IBS in different people.

Functional gastrointestinal (GI) disorders such as IBS are problems with brain-gut interaction—how your brain and gut work together. Experts think that problems with brain-gut interaction may affect how your body works and cause IBS symptoms. For example, in some people with IBS, food may move too slowly or too quickly through the digestive tract, causing changes in bowel movements. Some people with IBS may feel pain when a normal amount of gas or stool is in the gut.

Certain problems are more common in people with IBS. Experts think these problems may play a role in causing IBS. These problems include

  • stressful or difficult early life events, such as physical or sexual abuse
  • certain mental disorders, such as depression, anxiety, and somatic symptom disorder
  • bacterial infections in your digestive tract
  • small intestinal bacterial overgrowth, an increase in the number or a change in the type of bacteria in your small intestine
  • food intolerances or sensitivities, in which certain foods cause digestive symptoms

Research suggests that genes may make some people more likely to develop IBS.

November 2017
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This content is provided as a service of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), part of the National Institutes of Health. The NIDDK translates and disseminates research findings through its clearinghouses and education programs to increase knowledge and understanding about health and disease among patients, health professionals, and the public. Content produced by the NIDDK is carefully reviewed by NIDDK scientists and other experts.

The NIDDK would like to thank:
Lin Chang, M.D., David Geffen School of Medicine, University of California Los Angeles