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Irritable Bowel Syndrome (IBS)

Last Updated: Mar 1, 2019


Irritable bowel syndrome (IBS) is a disorder of the digestive tract characterized by recurring symptoms of abdominal pain, cramping, and excess gas associated with hard stools (constipation) or watery stools (diarrhea). IBS is not a disease; instead it is considered a functional disorder in which the intestines behave abnormally, but display no visible evidence of disease or damage to the intestinal wall. For patients, this is a long-term condition, but it is not life threatening.

Small and large intestines

IBS is the most common gastrointestinal disorder, affecting 10-15% of the adult population. It is more likely to develop in women than men, and the age of onset is typically under 45.

IBS was sometimes called spastic colon or spastic bowel, due to the presence of abnormal muscle spasms in those suffering from it. However, with greater understanding of the full nature of IBS, these terms are no longer used synonymously with this disorder, since muscle spasms are not necessarily present.

Similarly, IBS is also occasionally called nervous bowel, since the medical community recognized connections between the disorder and psychological factors such as anxiety. Because nervous bowel as a term would appear to address only some of the mental causes of IBS without the observable physical causes, the term does not adequately describe this disorder.

Irritable bowel syndrome differs from inflammatory bowel disease, in which the intestines show visible evidence of disease characterized by chronic inflammation and ulceration of the lining of the intestinal wall.

Causes and Risk Factors

The cause of IBS is unknown, but emotional stress, certain foods, and other factors exacerbate the symptoms.

Research offers the following observations:


With IBS, patients experience repeated episodes of lower abdominal pain, cramping, excess gas, abdominal bloating, and a change in bowel habits (either constipation or diarrhea). Some patients describe a mixture of constipation alternating with diarrhea.

There is no cure for IBS, and many patients experience recurring symptoms over the course of their lifetime.

Diagnosis and Treatment

IBS is diagnosed when a patient experiences abdominal discomfort occurring three or more times a month over a three-month period in the absence of gastrointestinal disease or injury. The diagnosis is confirmed by a normal physical examination and normal diagnostic test results.

When IBS is suspected, doctors may perform the following diagnostic tests to be sure there is no other gastrointestinal disorder to explain the symptoms:

The X-rays and colonoscopy are not performed unless a patient has alarming signs and symptoms such as anemia, weight loss, and rectal bleeding. If a patient is over age 50 and has symptoms of IBS, a colonoscopy is usually performed to check for colon cancer.

Because there is no cure for IBS, the goal of treatment is to control a patient’s predominant symptoms. The cornerstones of treatment are dietary and lifestyle changes, medications, probiotics, and mental health therapy. Surgery has no benefit and should be avoided.

Dietary and Lifestyle Changes


Mental Health Treatment

For some patients, therapies for psychological disorders may also relieve their IBS symptoms by addressing the emotional stress and mental problems linked to the condition. Psychotherapy involves exploring a patient’s thoughts and maladaptive behaviors and identifying effective coping techniques.

Alternative Treatment

Acupuncture (an alternative therapy that involves sticking the skin with small needles) may help alleviate IBS symptoms, but further studies are needed.


The cause of IBS is not well understood and effective preventive measures are not established. Researchers believe that both physical and mental health problems impact this condition. Although there is no cure for IBS, the condition is not life threatening and symptoms can improve with a range of dietary, medical, and mental health treatments.


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Tina Shahian, PhD

Tina is a writer for Innerbody Research, where she has written a large body of informative guides about health conditions.


A communication specialist in life science and biotech subjects, Tina’s successful career is rooted in her ability to convey complex scientific topics to diverse audiences. Tina earned her PhD in Biochemistry from the University of California, San Francisco and her BS degree in Cell Biology from U.C. Davis. Tina Shahian’s Linkedin profile.


In her spare time, Tina enjoys drawing science-related cartoons.