Irritable bowel syndrome (IBS) is a disorder that leads to abdominal pain and bowel changes.
IBS is not the same as inflammatory bowel disease (IBD).
The reasons why IBS develops are not clear. It can occur after a bacterial infection or a parasitic infection (giardiasis) of the intestines. This is called postinfectious IBS. There may also be other triggers, including stress.
The intestine is connected to the brain using hormone and nerve signals that go back and forth between the bowel and the brain. These signals affect bowel function and symptoms. The nerves can become more active during stress. This can cause the intestines to be more sensitive and contract more.
IBS can occur at any age. Often, it begins in the teen years or early adulthood. It is twice as common in women as in men.
It is less likely to begin in older people above 50 years of age.
About 10% to 15% of people in the United States have symptoms of IBS. It is the most common intestinal problem that causes people to be referred to a bowel specialist (gastroenterologist).
IBS symptoms vary from person to person, and range from mild to severe. Most people have mild symptoms. You are said to have IBS when symptoms are present for at least 3 days a month for a period of 3 months or more.
The main symptoms include:
Pain and other symptoms will often be reduced or go away after a bowel movement. Symptoms may flare up when there is a change in the frequency of your bowel movements.
People with IBS may go back and forth between having constipation and diarrhea or have or mostly have one or the other.
The symptoms may get worse for a few weeks or a month, and then decrease for a while. In other cases, symptoms are present most of the time.
You may also lose your appetite if you have IBS. However, blood in stools and unintentional weight loss are not a part of IBS.
There is no test to diagnose IBS. Most of the time, your health care provider can diagnose IBS based on your symptoms. Eating a lactose-free diet for 2 weeks may help the provider identify lactase deficiency (or lactose intolerance).
The following tests may be done to rule out other problems:
Your provider may recommend a colonoscopy. During this test, a flexible tube is inserted through the anus to examine the colon. You may need this test if:
Other disorders that can cause similar symptoms include:
The goal of treatment is to relieve symptoms.
In some cases of IBS, lifestyle changes can help. For example, regular exercise and improved sleep habits may reduce anxiety and help relieve bowel symptoms.
Dietary changes can be helpful. However, no specific diet can be recommended for IBS because the condition differs from one person to another.
The following changes may help:
Talk with your provider before taking over-the-counter medicines.
No one medicine works for everyone. Some that your provider may suggest include:
Psychological therapy or medicines for anxiety or depression may help with the problem.
IBS may be a life-long condition. For some people, symptoms are disabling and interfere with work, travel, and social activities.
Symptoms often get better with treatment.
IBS does not cause permanent harm to the intestines. Also, it does not lead to a serious disease, such as cancer.
Call your provider if you have symptoms of IBS or if you notice changes in your bowel habits that do not go away.
Reviewed By: Michael M. Phillips, MD, Clinical Professor of Medicine, The George Washington University School of Medicine, Washington, DC. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.