Irritable Bowel Syndrome is a functional gastrointestinal (GI) disorder, meaning symptoms are caused by changes in how the GI tract works. People with a functional GI disorder may have frequent symptoms; however, the GI tract does not become damaged. IBS is a group of symptoms that occur together, not a disease. In the past, IBS was called colitis, mucous colitis, spastic colon, nervous colon, and spastic bowel. The name was changed to reflect the understanding that the disorder has physical causes and is not a product of a person’s imagination.

IBS is diagnosed when a person has had abdominal pain or discomfort at least three times a month for the last 3 months without other disease or injury that could explain the pain. The pain or discomfort of IBS may occur with a change in stool frequency or consistency or can be relieved by a bowel movement.

IBS is often classified into four subtypes based on a person’s usual stool consistency. These subtypes are important because they affect the types of treatment that are most likely to improve the person’s symptoms.

The four subtypes of IBS are:

• IBS with constipation (IBS-C)
  • hard or lumpy stools at least 25% of the time
  • loose or watery stools less than 25% of the time
• IBS with diarrhea (IBS-D)
  • loose or watery stools at least 25% of the time
  • hard or lumpy stools less than 25% of the time
• Mixed IBS (IBS-M)
  • hard or lumpy stools at least 25% of the time
  • loose or watery stools at least 25% of the time
• Unsubtyped IBS (IBS-U)
  • hard or lumpy stools less than 25% of the time
  • loose or watery stools less than 25% of the time

The most common symptoms of IBS are abdominal pain or discomfort, often reported as cramping, along with changes in bowel habits. To meet the definition of IBS, the pain or discomfort will be associated with at least two of the following three symptoms:

• bowel movements that occur more or less often than usual
• stool that appears less solid and more watery, or harder and lumpier, than usual
• bowel movements that improve the discomfort

Other symptoms of IBS may include:

• diarrhea—having loose, watery stools three or more times a day and feeling an urgency to have a bowel movement.
• constipation—having fewer than three bowel movements a week.
  During a bowel movement, stools can be hard, dry, and small, making them difficult to pass. Some people find it painful and often have to strain to have a bowel movement.
• feeling that a bowel movement is incomplete.
• passing mucus—a clear liquid made by the intestines that coats and protects tissues in the GI tract.
• abdominal bloating.

Symptoms may often occur soon after eating a meal. To meet the definition of IBS, symptoms must occur at least three times a month.

The causes of IBS are not well understood. Researchers believe a combination of physical, dietary, and mental stress can lead to and exacerbate IBS.

To diagnose IBS, a health care provider will conduct a physical exam and take a complete medical history. The medical history will include questions about symptoms, family history of GI disorders, recent infections, medications, and stressful events related to the onset of symptoms. An IBS diagnosis requires that symptoms started at least 6 months prior and occurred at least three times a month for the previous 3 months.

Further testing is not usually needed, though the health care provider may perform a blood test to screen for other problems. Additional diagnostic tests may be needed based on the results of the screening blood test and for people who also have signs such as:

• fever
• rectal bleeding
• weight loss
• anemia—too few red blood cells in the body, which prevents the body from getting enough oxygen
• family history of colon cancer
• family history of inflammatory bowel disease—long-lasting disorders that cause irritation and ulcers, or sores, in the GI tract
• family history of celiac disease—an abnormal immune reaction to gluten, a protein found in wheat, rye, and barley, that damages the lining of the small intestine and prevents absorption of nutrients

Though IBS does not have a cure, the symptoms can be treated with a combination of:

• changes in diet and nutrition
• medications for pain, constipation, or diarrhea
• therapies for mental stress

For more information on IBS visit the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)

*Information from the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), the Colon Cancer Alliance and