Irritable Bowel Syndrome


Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) is the most common functional gastrointestinal (GI) disorder with worldwide prevalence rates ranging from 9-23 percent and U.S. rates generally in the area of 10-15 percent. Functional disorders are conditions where there is an absence of structural or biochemical abnormalities on diagnostic tests, which could explain symptoms.

IBS is best understood as a long-term or recurrent (chronic) disorder of gastrointestinal functioning. It is characterized by multiple symptoms involving a disturbance in the regulation of bowel function that results in unusual sensitivity and muscle activity. These disturbances can produce symptoms of abdominal pain or discomfort, bloating or a sense of gaseousness, and altered bowel habits (diarrhea and/or constipation).

Not all individuals with IBS symptoms seek medical care for their symptoms. Nevertheless,

there are between 2.4 and 3.5 million annual physician visits for IBS in the United States alone. IBS is the most common disorder diagnosed by gastroenterologists (doctors who specialize in digestive diseases or disorders) and accounts for up to 12 percent of total visits to primary care providers. The cost to society in terms of direct medical expenses and indirect costs associated with loss of productivity and work absenteeism is considerable estimates range from $21 billion or more annually.

Symptoms of IBS

Abdominal pain and/or discomfort is the key symptom of IBS and is often relieved with the passing of a bowel movement (defecation). There are many causes for abdominal pain, but in IBS, the pain or discomfort is associated with a change in bowel habits. While everyone suffers from an occasional bowel disturbance, for those with IBS the symptoms are more severe, or occur more often either continuously or off and on. IBS affects men and women of all ages.

Symptoms can vary and sometimes seem contradictory, such as alternating diarrhea and constipation. The intensity and location of abdominal pain in IBS are highly variable, even at different times within a single person. The symptoms of IBS are produced by abnormal functioning of the nerves and muscles of the bowel. In IBS there is no evidence of an organic disease (where structural or biochemical abnormalities are found), yet, something—a "dysregulation" between the brain, the gut, and the central nervous system—causes the bowel to become "irritated," or overly sensitive to stimuli. Symptoms may occur even in response to normal events, such as eating a meal.

Upper gastrointestinal symptoms are commonly reported by IBS patients with 25 percent to 50 percent of patients reporting heartburn, nausea, abdominal fullness, and bloating. In addition, a significant number report intermittent upper abdominal discomfort or pain (dyspepsia).

Many IBS patients also report non-gastrointestinal symptoms such as fatigue, muscle pain, sleep disturbances, and sexual dysfunction. Up to 66 percent of IBS patients report non-gastrointestinal symptoms compared to less than 15 percent of healthy individuals. These non-gastrointestinal symptoms may be due to IBS coexistence with another disease or condition such as fibromyalgia, chronic fatigue syndrome, and interstitial cystitis. For example, the estimated prevalence of IBS in patients with fibromyalgia (FMS) is 30 percent or more with similar findings of FMS in patients with irritable bowel syndrome.

Diagnosis of IBS

There are no physical findings or diagnostic tests that confirm the diagnosis of IBS. Therefore, diagnosis of IBS involves identifying certain symptoms consistent with the disorder and excluding other medical conditions that may have a similar clinical presentation.

The first step in making a positive diagnosis of IBS is for a doctor to identify if an individual has the symptoms of IBS. This is best determined by the use of the Rome Criteria, which is a collection of the most common symptoms that typify the disorder. These include abdominal pain or discomfort for several months that is associated with two of the following: 1) the pain or discomfort is relieved by defecation, 2) the pain or discomfort is associated with an increase or decrease in stool frequency, and/or 3) the pain or discomfort is associated with the stools becoming harder or softer in consistency.

The next important step is to exclude signs and symptoms that are suggestive of a condition other than IBS which may present with symptoms similar to those seen in IBS—but with uniquely identifying features—such as inflammatory bowel disease or GI infections. A medical history and physical examination, laboratory, and GI tests can help to exclude these other diagnoses. Typical signs and symptoms the physician will look for include anemia and other abnormal blood tests, blood in the stool, unexplained weight loss, fever, and family history of inflammatory bowel disease or colon cancer. These signs and symptoms are usually not explained by IBS and can represent other medical problems. When these symptoms occur, they should be brought immediately to the attention of a physician.


Patients with mild IBS symptoms comprise the most prevalent group, and are usually treated by primary care practitioners, rather than specialists. They do not see a clinician very often, and usually maintain normal daily activities. Treatment is directed toward education, reassurance, achievement of a healthier lifestyle, and occasional medication. Dietary changes work for some and might include avoiding or reducing offending foods that may trigger symptoms. The influence of diet is unique to each individual and there is no generalized dietary advice that will work for everyone.

Pharmacologic (drug) therapy is best used in IBS patients with moderate to severe symptoms which do not respond to physician counseling and dietary changes. First line treatment has traditionally been aimed at treating the most bothersome symptom because of the lack of effective treatment for the overall improvement of multiple symptoms in IBS patients. However, new therapies for IBS have been recently introduced and have been shown to effectively treat multiple symptoms of IBS in some people.

Other treatments may include hypnosis, relaxation training, and behavioral therapies. These can variously help to reduce pain and to manage symptoms. Complementary and alternative therapies ranging from the use of probiotics to yoga are also being evaluated for the treatment of IBS.

For individuals with IBS, effective diagnosis and treatment starts with the recognition of the validity of symptom complaints. Working in partnership with a physician or care-provider can help achieve the best possible results. Once a diagnosis is made it is helpful to develop a treatment plan and an outcome goal in an effort to control symptoms. Each individual’s symptoms may vary and respond differently to treatment.


IBS is a common, chronic disorder characterized by flare-ups and remissions, which presents with symptoms of abdominal pain and/or discomfort and altered bowel habits. It has a chronic relapsing course and can overlap with other functional GI (e.g., dyspepsia) and non-GI (e.g., fibromyalgia) disorders.

Doctors diagnose IBS based on identifying symptom criteria and excluding organic disease with minimal diagnostic evaluation. This "positive" diagnosis of IBS (as opposed to a diagnosis of exclusion), if made properly, is rarely associated with other explanations for symptoms. Although there are many expensive and sophisticated tests available for the evaluation of IBS symptoms, these are generally not needed for patients with typical symptoms and no features suggestive of organic diseases.

Future studies will further enhance our understanding of this condition and lead to newer, more effective treatments. The fact that definite structural or biochemical abnormalities for these disorders cannot be detected with conventional diagnostic techniques does not rule out the possibility that neurobiological alterations will eventually be identified to explain fully the symptoms of most functional disorders.

The treatment of IBS is based on a working partnership between you and your doctor. You can help by giving your doctor as much information as possible on your symptoms and how they respond to treatment. The key to achieving relief for IBS is for patients to understand that IBS is a complex motor and sensory disorder. A strong partnership between a knowledgeable patient and an empathetic, knowledgeable health care provider can produce significant improvement and control over symptoms for most individuals with IBS.

IFFGD is a nonprofit education and research organization. They offer a wealth of information about IBS and other functional disorders through their publications and web sites. Find out more by going to their web site at or - or call them toll-free at 1-888-964-2001.

© Copyright 2006 International Foundation for Functional Gastrointestinal Disorders (IFFGD).


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