Irritable Bowel Syndrome (IBS)

Medically reviewed by: Gary H. Hoffman, MD

What is irritable bowel syndrome?

Irritable bowel syndrome (IBS) is a common disorder that may affect as many as 30% of all Americans at some point during their lives. A ‘syndrome’ is a pattern of symptoms, such as pain and bloating, which tend to occur together. IBS is not a ‘disease’ in the sense that it can be acquired or transmitted, like a cold. It is not life-threatening.

What are the symptoms of IBS?

People with IBS may experience mostly constipation or mostly diarrhea, or they may have constipation at some times, and diarrhea at other times. In addition, IBS may produce a crampy or a gassy bloated feeling in the abdomen. Mucus is sometimes seen in bowel movements, and this is also a part of IBS.

What causes IBS?

The underlying cause of this disorder is an abnormality in the way the intestinal muscles contract. These muscles form the outer layer of the intestine. The muscles work automatically to move food along the intestine from the mouth to the rectum and out of the anus. We cannot voluntarily control these muscles like we can those in our arms or legs. The muscles are, however, affected by what we eat and by stress. The muscles appear normal under the microscope but may not function normally at certain times. IBS then is a disorder of the function of the muscles. In a patient with IBS, these muscles may contract too forcefully, causing cramps, or they may contract too slowly or too weakly, causing constipation. Diarrhea results when the muscles contract too rapidly.

What role does stress play in IBS?

The nervous system and the intestine are closely connected by nerve fibers that control the automatic functioning of the intestinal muscles. It is well known that emotional stress, by, activating these nerve fibers, may cause ‘butterflies in the stomach.’ Many people, when nervous or anxious, may experience nausea or diarrhea. These same pathways between the brain and the intestines can result in constipation, diarrhea, cramping, or bloating.

Does this mean that if I ignore stress, my IBS will improve?

No. Ignoring the stress in our lives may actually make IBS symptoms worse. While we may not be able to control the effect stress has on our intestines, it is often possible to diminish the sources of stress in our lives – high-pressure jobs, family tensions, etc. By reducing the sources of stress, many people do notice a great improvement in their irritable bowel syndrome.

How can the doctor tell whether the problem is IBS or something else?

A careful medical history and physical examination are essential to be certain that the symptoms are not caused by other types of problems. Tests such as a flexible sigmoidoscopic examination, a test for hidden blood in the stool (hemoccult test), or an x-ray or Endoscopic examination of the lower intestines are often done to be sure that other intestinal conditions such as cancer, diverticulitis, or inflammation of the intestines are not present. If these tests are normal, both the patient and the physician may feel reassured.

How can IBS be treated?

Several things are of help to people with IBS. The knowledge that IBS is not serious can relieve some anxiety, diminishing some of the stress which may be contributing to the problem. Increasing the amount of non-digestible, bulk forming foods, or ‘roughage’, such as bran, in the diet is often all that is needed to relieve the symptoms. This roughage has two beneficial effects; it causes a large stool, which enlarges the intestine, stretching the intestinal muscles and making cramps less severe. Bulk also results in a softer stool, making passage of stools along the intestine easier. This is because the bulk agent absorbs water and helps in keeping the stool soft and moist. If diarrhea is the main problem, the bulk agents absorb the excess water in the intestine, resulting in thicker stools. When constipation is the major complaint, additional water should be provided in the diet with the bulk agent to soften the stool.

When dietary roughage alone does not provide adequate relief from cramping and bloating, medications are available that act directly on the intestinal muscles, making the contractions less strong. Some people get more relief from one medication than from another, so sometimes it is helpful to try more than one type.

Are there any foods to be avoided?

Sometimes caffeine, alcohol, and nicotine may aggravate the symptoms of IBS. Dairy products such as cheese and milk may cause diarrhea in some people but may constipate others.

How long does the treatment take to resolve the symptoms?

Resolution is often a slow process and may take up to six months for definite improvement. Patience is extremely important in dealing with this problem.

Can IBS lead to more serious problems?

IBS does not cause cancer, bleeding, or inflammatory bowel disease such as ulcerative colitis. IBS at one time was called ‘spastic colitis’ but this is in no way related to the serious forms of colitis. In order to avoid confusion with true colitis, this term is no longer used. IBS may, over the long term, be associated with diverticulosis, a benign condition that only rarely results in diverticulitis. Treatment of IBS with bulk agents helps to prevent diverticulosis and other colon problems.

Will I always have this problem?

The tendency for the intestine to respond to stress will always be present. By focusing on an appropriate IBS diet, along with careful management of roughage and medications, the symptoms of IBS can be greatly improved or eliminated. Mild symptoms may be experienced from time to time, but are rarely any more than a minor nuisance.

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