Irritable bowel syndrome

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Irritable bowel syndrome
Last literature review version 17.1: January 2009
This topic last updated: May 8, 2008
Author Arnold Wald, MD
UpToDate


INTRODUCTION — Irritable bowel syndrome (IBS) is a chronic condition of the digestive system. Its primary symptoms are abdominal pain and altered bowel habits (eg, constipation and/or diarrhea), but these symptoms have no identifiable cause.

IBS is the most commonly diagnosed gastrointestinal condition and is second only to the common cold as a cause of absence from work. An estimated 10 to 20 percent of people in the general population experience symptoms of IBS, although only about 15 percent of affected people actually seek medical help.

Several treatments and therapies are available for IBS. These measures help alleviate symptoms, but do not cure the condition. The chronic nature of IBS and the challenge of controlling its symptoms can be frustrating for both patients and healthcare providers.

CAUSES — There are a number of theories about how and why IBS develops. Despite intensive research, the cause is not clear.

One theory suggests that IBS is caused by abnormal contractions of the colon and intestines (hence the term "spastic bowel," which has sometimes been used to describe IBS). Vigorous contractions of the intestines can cause severe cramps, providing the rationale for some of the treatments of IBS, such as antispasmodics and fiber (both of which help to regulate the contractions of the colon). However, abnormal contractions do not explain IBS in all patients, and it is unclear whether the contractions are a symptom or cause of the disorder.
Some people develop IBS after a severe gastrointestinal infection (eg, Salmonella or Campylobacter). It is not clear how the infection triggers IBS to develop, and most people with IBS do not have a history of these infections.
People with IBS who seek medical help are more likely to suffer from anxiety and stress than those who do not seek help. Stress and anxiety are known to affect the intestine; thus, it is likely that anxiety and stress worsen symptoms. However, stress or anxiety are probably not the cause. Some studies have suggested that IBS is more common in people who have a history of physical, verbal, or sexual abuse.
Food intolerances are common in patients with IBS, raising the possibility that IBS is caused by food sensitivity or allergy. This theory has been difficult to prove, although it continues to be studied. The best way to detect an association between symptoms of IBS and food sensitivity is to eliminate certain food groups systematically (a process called an elimination diet), which should only be considered for patients in the care of a doctor or nutritionist. Eliminating foods without assistance can lead to omission of important sources of nutrition. In addition, unnecessary dietary restrictions can further worsen a person's quality of life.
A number of foods are known to cause symptoms that mimic or aggravate IBS, including dairy products (which contain lactose), legumes (such as beans), and cruciferous vegetables (such as broccoli, cauliflower, Brussels sprouts, and cabbage). These foods increase intestinal gas, which can cause cramps. Several medications also have effects on the intestines that may contribute to symptoms.

Many researchers believe that IBS is caused by heightened sensitivity of the intestines to normal sensations (so-called "visceral hyperalgesia"). This theory proposes that nerves in the bowels are overactive in people with IBS, so that normal amounts of gas or movement are perceived as excessive and painful. Some patients with severe IBS feel better when treated with medications that decrease pain perception in the intestine (such as low doses of imipramine or nortriptyline, see "Antidepressants" below).
SYMPTOMS — IBS usually begins in young adulthood. Women are twice as likely as men to be diagnosed with IBS in the United States and other western countries. In other countries (such as India), an equal number of men and women are diagnosed with IBS. The hallmark of IBS is abdominal pain in association with altered bowel habits (diarrhea and/or constipation).

Abdominal pain — Abdominal pain is typically crampy, varying in intensity, and located in the lower left abdomen. However, the nature, severity, and location of pain can vary considerably from person to person. Some people notice that emotional stress and eating worsen the pain, and that having a bowel movement relieves the pain. Some women with IBS notice an association between pain episodes and their menstrual cycle.

Altered bowel habits — Altered bowel habits are a second hallmark of IBS. This can include diarrhea, constipation, or alternating diarrhea and constipation. If diarrhea is the more common pattern, the condition is called diarrhea-predominant IBS; if constipation is more common, the condition is called constipation-dominant IBS.

Diarrhea — The diarrhea of IBS causes frequent loose stools of small to moderate volume. Bowel movements usually occur during the daytime, and most often in the morning or after meals. Diarrhea is often preceded by a sense of extreme urgency and followed by a feeling of incomplete evacuation. About one-half of people with IBS also notice mucous discharge with diarrhea. Diarrhea occurring during sleep does not occur in IBS and suggests another diagnosis. (See "Patient information: Chronic diarrhea in adults").

Constipation — The constipation of IBS can last from days to months. Stools are often hard and pellet-shaped. Sometimes people do not feel empty after a bowel movement, even when the rectum is empty. This faulty sensation can lead to straining, sitting on the toilet for prolonged periods of time, and the use of enemas and laxatives for relief. (See "Patient information: Constipation in adults").

Other symptoms — Other symptoms include bloating, gas, belching, heartburn, difficulty swallowing, an early feeling of fullness with eating, and nausea.

Non-gastrointestinal symptoms can also occur, including frequent and urgent urination, painful menstrual periods, and pain with sex. (See "Patient information: Painful bladder syndrome and interstitial cystitis").

DIAGNOSIS — Several intestinal disorders have symptoms that are similar to IBS. Examples include malabsorption (abnormal absorption of nutrients), inflammatory bowel disease (such as ulcerative colitis and Crohn's disease), and microscopic and eosinophilic colitis (uncommon diseases associated with intestinal inflammation).

Because there is no single diagnostic test for IBS, many clinicians compare a person's symptoms to formal sets of diagnostic criteria (such as the Rome or Manning criteria) (show table 1). However, these criteria are not accurate in distinguishing IBS from other conditions in all patients. Thus, a medical history, physical examination, and select tests can help to rule out other medical conditions.

Medical history — The diagnosis of IBS begins with a comprehensive medical history. The medical history will include a discussion of the nature, duration, and severity of gastrointestinal and other symptoms. Sometimes a medical history reveals that dietary factors or drugs are actually causing a person's symptoms. Clinicians routinely ask about past and present physical or sexual abuse and stress because these factors may have a role in IBS.

Physical examination — The physical examination is usually normal in people with IBS, but it can help detect or rule out conditions that mimic IBS.

Tests — Most clinicians order routine blood tests in people with suspected IBS; these tests are usually normal, but they can help rule out other medical conditions. Sometimes, based upon certain symptoms or other factors in the medical history, a clinician will order thyroid function tests and/or stool tests to check for certain other conditions. Some clinicians also order more invasive tests, such as sigmoidoscopy or colonoscopy, especially in people over the age of 40 years. These tests allow the physician to see the inside of the colon. (See "Patient information: Colonoscopy" and see "Patient information: Flexible sigmoidoscopy").

TREATMENT — There are a number of different treatments and therapies for IBS. Treatments are often combined to reduce the pain and other symptoms of IBS, and it may be necessary to try more than one combination to find the one that is most helpful. Treatment is usually a long-term process; during this process, it is important to communicate with your healthcare provider about symptoms, concerns, and any stressors or home/work/family problems that develop.

Monitoring — The first step in treating IBS is usually to monitor symptoms, daily habits, and any other factors that may affect gastrointestinal function. This can help to identify factors that worsen symptoms in some people with IBS, such as lactose or other food intolerances and stress. A daily diary can be helpful (show figure 1).

Dietary changes — It is reasonable to try eliminating foods that may aggravate IBS, although this should be done with the assistance of a healthcare provider. Eliminating foods without assistance can potentially worsen symptoms or cause new problems if important food groups are omitted.

Lactose — Many clinicians recommend temporarily eliminating milk products since lactose intolerance is common and can aggravate IBS or cause symptoms similar to IBS. The greatest concentration of lactose is found in milk and ice cream, although it is present in smaller quantities in yogurt, cottage and other cheeses, and any prepared foods that contain these ingredients (show table 2). All lactose containing products should be eliminated for two weeks, with a gradual reintroduction of these products depending upon symptoms. People who avoid lactose should take a calcium supplement that contains at least 1000 mg of calcium and 400 IU of vitamin D. (See "Patient information: Calcium and Vitamin D for bone health").

Foods that cause gas — Several foods are only partially digested in the small intestines. When they reach the colon (large intestine), further digestion takes place, which may cause gas and cramps. Eliminating these foods temporarily is reasonable if gas or bloating is bothersome. The most common gas-producing foods are legumes (such as beans) and cruciferous vegetables (such as cabbage, Brussels sprouts, cauliflower, and broccoli). In addition, some patients have trouble with onions, celery, carrots, raisins, bananas, apricots, prunes, sprouts, and wheat. (See "Patient information: Gas and bloating").

Foods that are easier — Table 3 provides a list of foods that may be easier to digest in people with IBS (show table 3).

Increasing dietary fiber — Increasing dietary fiber (either by adding certain foods to the diet or using fiber supplements) can relieve symptoms in some people with IBS, particularly people who have constipation (show table 4A-4C). By reading the product information panel on the side of the package, patients can determine the number of grams of fiber per serving (show figure 1). It may also be helpful in people with diarrhea predominant symptoms since it can improve the consistency of stools. (See "Patient information: High fiber diet").

A bulk-forming fiber supplement (such as psyllium or methylcellulose ) may be recommended to increase fiber intake since it is difficult to consume enough fiber in the diet (show table 5). Fiber supplements should be started at a low dose and increased slowly over several weeks to reduce the symptoms of excessive intestinal gas, which can occur in some people when beginning fiber therapy. Fiber can make some people with IBS more bloated and uncomfortable. If this happens, it is best to decrease fiber intake and consider other laxative treatments for constipation. (See "Patient information: Constipation in adults").

Psychosocial therapies — Stress and anxiety can worsen IBS in some people. The best approach for reducing stress and anxiety depends upon the individual and the severity of symptoms. Patients should have an open discussion with their clinician about the possible role that stress and anxiety could be having on symptoms, and together decide upon the best course of action.

Some patients benefit from formal counseling with or without antidepressant or antianxiety medications. Other treatments such as hypnosis and cognitive behavioral therapy may also be helpful. Hypnosis is a state of altered consciousness that allows a patient to focus away from their anxiety or stress. Patients who are hypnotized are not sleeping, but are actually in a state of heightened imagination, similar to daydreaming. An expert can hypnotize an individual or a patient can learn self-hypnosis techniques.
Cognitive behavioral therapy helps a person to focus on a particular problem in a limited time period. Patients learn how their thoughts contribute to anxiety or stress and learn how to change these thoughts.

Participation in a support group can also be valuable.
Many patients find that daily exercise are helpful in maintaining a sense of well-being. Exercise can also have favorable effects on bowel action. (See "Patient information: Exercise").
Medications — Although many drugs are available to treat the symptoms of IBS, these drugs do not cure the condition. They are primarily used to relieve symptoms. The choice among these medications depends in part upon whether a person has diarrhea, constipation, or pain- predominant IBS. Furthermore, the effectiveness of specific drugs varies from one person to another. As a general rule, medications are reserved for people whose symptoms have not adequately responded to more conservative measures such as changes in diet and fiber supplements.

Anticholinergic medications — Anticholinergic drugs block the nervous system's stimulation of the gastrointestinal tract, helping to reduce severe cramping and irregular contractions of the colon. Drugs in this category include dicyclomine (Bentyl®) and hyoscyamine (Levsin®). These drugs may be particularly helpful when taken preventively (ie, before symptoms) and thus are most helpful for patients who can predict the onset of their symptoms. Common side-effects include dry mouth and eyes and blurred vision.

Antidepressants — Many tricyclic antidepressants (TCAs) have a pain relieving effect in patients with IBS. The dose of TCAs is typically much lower than that used for treating depression. It is believed that these drugs reduce pain perception when used in low doses, although the exact mechanism of their benefit is unknown.

TCAs commonly used for pain management include amitriptyline, desipramine, and nortriptyline. Patients beginning TCAs commonly experience fatigue; this is not always an undesirable side effect since it can help improve sleep when TCAs are taken in the evening. TCAs are generally started in low doses and increased gradually. Their full effect may not be seen for three to four weeks.

TCAs also slow movement of contents through the gastrointestinal tract and may be most helpful in people with diarrhea predominant IBS.

Another class of antidepressants, the selective serotonin reuptake inhibitors, are recommended for people who have both IBS and depression. Common SSRIs include fluoxetine (Prozac®), sertraline (Zoloft®), paroxetine (Paxil®), citalopram (Celexa®), and escitalopram (Lexapro®) Other antidepressant medications that may be recommended include mirtazapine (Remeron®), venlafaxine (Effexor®), and duloxetine (Cymbalta®). (See "Patient information: Depression treatment options for adults").

Antidiarrheal drugs — The drugs loperamide (Imodium®) or diphenoxylate with atropine (Lomotil®) can help slow the movement of stool through the digestive tract. Loperamide and diphenoxylate/atropine are most helpful in people with diarrhea-predominant IBS. However, clinicians usually recommend that these drugs should only be used as needed rather than on a continuous basis.

Anxiolytic drugs — Anxiolytic drugs reduce anxiety. Diazepam (Valium®) belongs to this class of drugs. Anxiolytic drugs are occasionally prescribed for people with short-term anxiety that is worsening their IBS symptoms. However, these drugs should only be taken for short periods of time since they can cause addiction and withdrawal syndromes.

Alosetron — Alosetron (Lotronex®) blocks a hormone that is involved in intestinal contractions and sensations. It is approved to treat women with IBS whose predominant symptom is diarrhea. However, it was withdrawn from the market soon after its introduction because of concerns related to safety. It was reintroduced and is currently available, although certain prescribing guidelines must be followed. Further information is available on the manufacturer's web site (www.lotronex.com).

Lubiprostone — Lubiprostone (Amitiza®) is available for treatment of severe constipation and irritable bowel syndrome in women >18 years who have not responded to other treatments. It works by increasing intestinal fluid secretion. It is expensive compared to other agents. Further testing is needed to clarify effectiveness and long-term safety.

Tegaserod — Tegaserod (Zelnorm®) is a prescription medication that was previously used for IBS symptoms. However, it was removed from the market in the United States in March 2007 due to concerns about an increased risk of heart attack, stroke, and severe chest pain. It was reintroduced in July 2007 for women under 55 who meet specific guidelines. Further information is available from the Federal Drug Administration's web site (www.fda.gov/bbs/topics/NEWS/2007/NEW01673.html).

Antibiotics — The role of antibiotics in the treatment of IBS remains unclear. There appear to be some patients whose IBS symptoms are due to overgrowth of bacteria in the intestines and who may benefit from antibiotic treatment. However, more research is needed before antibiotics are recommended for treatment of IBS.

HERBS AND NATURAL THERAPIES — A number of herbal and natural therapies have been advertised (especially on the internet) for the treatment of IBS. Unfortunately, there is no evidence supporting their benefit from carefully conducted studies. Although small studies may support some of these therapies, the studies are either too small or have major flaws that make definitive conclusions impossible.

Peppermint oil — There is some evidence supporting the use of peppermint oil, although it is difficult to make definitive conclusions. Peppermint oil can cause or worsen heartburn.
Acidophilus — There is increasing interest in the possible beneficial effects of "healthy" bacteria in a variety of intestinal diseases including IBS. Whether supplements containing these bacteria (such as acidophilus with or without "FOS" or Lactobacillus) are of any benefit is unproven.
Unproven — Chamomile tea is of unproven benefit in IBS. Furthermore, chamomile can aggravate allergies in people who tend to be allergic. People allergic to grasses may have an allergic reaction to chamomile. Evening primrose oil, a supplement containing gamma linolenic acid, is of unproven benefit. Fennel seeds are of unproven benefit.
Potentially unsafe — Wormwood is of unproven benefit and may be unsafe. Wormwood oil can cause damage to the nervous system. Comfrey is of unproven benefit and can cause serious liver problems.
PROGNOSIS — Although IBS can produce substantial physical discomfort and emotional distress, most people with IBS do not develop serious long-term health conditions. Furthermore, the vast majority of patients learn to control their symptoms and IBS does not decrease life expectancy.

Over time, less than 5 percent of people diagnosed with IBS will be diagnosed with another gastrointestinal condition. It is important to work with a clinician to monitor symptoms over time. If symptoms change over time, further testing may be recommended.

SUMMARY

Irritable bowel syndrome (IBS) is a common gastrointestinal disorder affecting approximately 10 to 20 percent of the population. Although the condition cannot be cured, treatments are available to alleviate symptoms.
No single cause of IBS has been identified, although there are theories that gastrointestinal abnormalities, food intolerance, and psychological issues may be involved. (See "Causes" above).
The primary symptoms of IBS are abdominal pain and changes in bowel habits (eg, diarrhea and/or constipation). Abdominal pain can vary in location and severity. Patients can experience primarily diarrhea, primarily constipation, or a alternating pattern of the two; additional gastrointestinal symptoms may also occur. (See "Symptoms" above).
There is no single diagnostic test for IBS, and several other gastrointestinal conditions produce similar symptoms; a patient's history, physical examination, and blood test results are all reviewed to rule out other disorders and establish a diagnosis of IBS. (See "Diagnosis" above).
There are many different treatments available to relieve the symptoms of IBS; these include the monitoring of symptoms and patterns, adjustment of the diet to increase fiber and eliminate foods that can worsen symptoms, psychosocial therapy (since stress may aggravate IBS), and medication. Treatments are often used in combination, and because of the variability of symptoms, different treatments work for different people. (See "Treatment" above).
Many herbal and natural therapies have been advertised for the treatment of IBS; however, these therapies have not been proven effective and they are not recommended. (See "Herbs and natural therapies" above).
Although IBS can cause pain and stress, the majority of patients are able to control their symptoms and live a normal life without developing serious health problems. (See "Prognosis" above).
WHERE TO GET MORE INFORMATION — Your healthcare provider is the best source of information for questions and concerns related to your medical problem. Because no two patients are exactly alike and recommendations can vary from one person to another, it is important to seek guidance from a provider who is familiar with your individual situation.

This discussion will be updated as needed every four months on our web site (www.uptodate.com/patients). Additional topics as well as selected discussions written for healthcare professionals are also available for those who would like more detailed information.

Some of the most pertinent include:

Patient Level Information:

Patient information: Chronic diarrhea in adults
Patient information: Constipation in adults
Patient information: Painful bladder syndrome and interstitial cystitis
Patient information: Colonoscopy
Patient information: Flexible sigmoidoscopy
Patient information: Calcium and Vitamin D for bone health
Patient information: Gas and bloating
Patient information: High fiber diet
Patient information: Exercise
Patient information: Depression treatment options for adults


Professional Level Information:
Alosetron hydrochloride (Lotronex) for irritable bowel syndrome
Approach to the patient with chronic diarrhea
Clinical manifestations and diagnosis of irritable bowel syndrome
Diagnostic approach to abdominal pain in adults
Intestinal gas and bloating
Lactose intolerance
Pathophysiology of irritable bowel syndrome
Probiotics for gastrointestinal disease
Treatment of constipation in adults
Treatment of irritable bowel syndrome


A number of web sites have information about medical problems and treatments, although it can be difficult to know which sites are reputable. Information provided by the National Institutes of Health, national medical societies and some other well-established organizations are often reliable sources of information, although the frequency with which they are updated is variable.

National Library of Medicine
(www.nlm.nih.gov/medlineplus/healthtopics.html)


National Institute of Diabetes and Digestive and Kidney Diseases
(www.niddk.nih.gov)


The American Gastroenterological Association
(www.gastro.org)


The American College of Gastroenterology
(www.acg.gi.org)


International Foundation for Functional Gastrointestinal Disorders (IFFGD)
(www.iffgd.org)


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Cremonini, F, Delgado-Aros, S, Camilleri, M. Efficacy of alosetron in irritable bowel syndrome: a meta-analysis of randomized controlled trials. Neurogastroenterol Motil 2003; 15:79.
Drossman, DA, Camilleri, M, Mayer, EA, Whitehead,WE. AGA technical review on irritable bowel syndrome. Gastroenterology 2002; 123:2108.
Drossman, DA. Functional abdominal pain syndrome. Clin Gastroenterol Hepatol 2004; 2:353.
Liu, J, Yang, M, Liu, Y, et al. Herbal medicines for treatment of irritable bowel syndrome. Cochrane Database Syst Rev 2006; :CD004116.
Spanier, JA, Howden, CW, Jones, MP. A systematic review of alternative therapies in the irritable bowel syndrome. Arch Intern Med 2003; 163:265.
Palsson, OS, Drossman, DA. Psychiatric and psychological dysfunction in irritable bowel syndrome and the role of psychological treatments. Gastroenterol Clin North Am 2005; 34:281.


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