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Irritable bowel syndrome
Classifications and external resources

ICD-10	K58
ICD-9	564.1
DiseasesDB	30638
MedlinePlus	000246
eMedicine	med/1190

In gastroenterology, irritable bowel syndrome (IBS) or spastic colon is a functional bowel disorder characterized by abdominal pain and changes in bowel habits which are not associated with any abnormalities seen on routine clinical testing. It is fairly common and makes up 20–50% of visits to gastroenterologists. Lower abdominal pain, and bloating associated with alteration of bowel habits and abdominal discomfort relieved with defecation are the most frequent symptoms. The abdominal pain type is usually described in a patient as either diarrhea-predominant (IBS-D), constipation-predominant (IBS-C) or IBS with alternating stool pattern (IBS-A). In some individuals, IBS may have an acute onset and develop after an infectious illness characterised by two or more of the following: fever, vomiting, acute diarrhea, positive stool culture. This post-infective syndrome has consequently been termed "post-infectious IBS" (IBS-PI) and is acute onset Rome II criteria positive. This condition is more homogenous, being mostly IBS-D and is drawing much clinical investigation.

Chronic functional abdominal pain (CFAP) is quite similar to, but less common than IBS. CFAP can be diagnosed if there is no change in bowel habits.

Because of the name, IBS can be confused with inflammatory bowel disease (IBD), a more serious condition.

Contents 1 Symptoms 2 Diagnosis 2.1 Diagnostic criteria 2.1.1 The Manning Criteria 2.1.2 The Rome Process 2.2 Differential diagnosis 2.3 Diagnostic tests 3 Pathophysiology 3.1 Visceral hyperalgesia 3.2 Post-infectious or post-antibiotic 3.3 Food allergies and sensitivities 3.4 Bacterial overgrowth 3.5 Stress 3.6 Hormones 4 Treatment 4.1 Diet 4.2 Medication 4.2.1 Initial treatments 4.2.2 Drugs affecting serotonin (5-HT) 4.2.3 Other agents 4.3 Psychotherapy and hypnotherapy 4.4 Alternative treatments 5 Epidemiology 6 Prognosis 7 References 8 External links

[edit] Symptoms

The range of symptoms relating to IBS is relatively broad, but the main symptom is usually abdominal pain or discomfort associated with changes in bowel habits in the absence of any apparent structural abnormality. The pain is commonly relieved by defecating or modulated by other triggers of gut motility. There is generally no pain when patients are asleep. Symptoms usually start in young adulthood.

[edit] Diagnosis

[edit] Diagnostic criteria

[edit] The Manning Criteria

In 1978, Manning et al. found, from questionnaire data, that IBS sufferers reported four common symptoms.<ref>Manning A, Thompson W, Heaton K, Morris A (1978). "Towards positive diagnosis of the irritable bowel.". Br Med J 2 (6138): 653-4. PMID 698649.</ref> The Manning Criteria was established to distinguish organic causes for symptoms from those of IBS.

[edit] The Rome Process

In 1992, the Rome I criteria were established by a multinational committee of specialists, which further refined the Manning Criteria. In 1998, the Rome Working Team proposed changes to the definition and diagnostic criteria for IBS to reflect new research data, and to improve clarity. These criteria have evolved, as the Rome Process has integrated fresh evidence and new conceptual approaches to the condition.

Physicians rely on a variety of procedures and laboratory tests to confirm a diagnosis. The cardinal requirement for the diagnosis of IBS is abdominal pain. The Rome II criteria is used to diagnose IBS after a careful examination of the patient's medical history and physical abdominal examination which looks for any 'red flag' symptoms. More recently, the Rome III criteria, incorporating some changes over the previous set of criteria, have been issued. The Rome II and III efforts have integrated pediatric contents to their set of criteria.

According to the Rome II committees and the Functional Brain Gut Research Group,<ref name="FBD2000-Rome">Thompson WG, Longstreth GL, Drossman DA et al. (2000). Functional Bowel Disorders. In: Drossman DA, Corazziari E, Talley NJ et al. (eds.), Rome II: The Functional Gastrointestinal Disorders. Diagnosis, Pathophysiology and Treatment. A Multinational Consensus. Lawrence, KS: Allen Press. ISBN 0-9656837-2-9.</ref> IBS can be diagnosed based on at least 12 weeks, which need not be consecutive, of the preceding 12 months there was abdominal discomfort or pain that had two out of three of these features:<ref name="IBSgroup2005-Criteria">Diagnostic Criteria. Irritable Bowel Syndrome Self Help and Support Group (2005). Retrieved on 2005-12-04.</ref>

• Relieved with defecation; and/or
• Onset associated with a change in frequency of stool; and/or
• Onset associated with a change in form (appearance) of stool.

Symptoms that cumulatively support the diagnosis of IBS:

• Abnormal stool frequency (for research purposes, "abnormal" may be defined as greater than 3 bowel movements per day and less than 3 bowel movements per week);
• Abnormal stool form (lumpy/hard or loose/watery stool);
• Abnormal stool passage (straining, urgency, or feeling of incomplete evacuation);
• Passage of mucus;
• Bloating or feeling of abdominal distention.

Supportive symptoms of IBS:

• A) Fewer than three bowel movements a week
• B) More than three bowel movements a day
• C) Hard or lumpy stools
• D) Loose (mushy) or watery stools
• E) Straining during a bowel movement
• F) Urgency (having to rush to have a bowel movement)
• G) Feeling of incomplete bowel movement
• H) Passing mucus (white material) during a bowel movement
• I) Abdominal fullness, bloating, or swelling

Diarrhea-predominant: At least 1 of B, D, F and none of A, C, E; or at least 2 of B, D, F and one of A or E.
Constipation-predominant: At least 1 of A, C, E and none of B, D, F; or at least 2 of A, C, E and one of B, D, F.

Red flag symptoms which are not typical of IBS:

• Pain that awakens/interferes with sleep
• Diarrhea that awakens/interferes with sleep
• Blood in the stool (visible or occult)
• Weight loss
• Fever
• Abnormal physical examination

An update to these criteria was issued at the Rome III conference and published in May 2006.<ref name="FBD2006-Rome">Longstreth GL, Thompson WG, Chey WD, Houghton LA, Mearin F, and Spiller RC. (2006). Functional Bowel Disorders. Gastroenterology 2006; 130:1480–1491'</ref> The validity of subtypes is called into question:

• The validity and stability of such subtypes over time is unknown and should be the subject of future research.
• Because of the characteristic symptom instability, we prefer the terms IBS with constipation and IBS with diarrhea instead of constipation- and diarrhea-predominant IBS. In this categorical system, many people whose features place them close to a subtype boundary change pattern without a major change in pathophysiology. Moreover, the heterogeneity and variable natural history of IBS significantly limit clinical trials of motility-active drugs and drug therapy in practice.

In addition to meeting these positive criteria, patients have initial laboratory testing with a complete blood count, basic chemistry panel, and an erythrocyte sedimentation rate. Diagnostic accuracy for IBS is over 95% when Rome II criteria are met, history and physical exam do not suggest any other cause, and initial laboratory testing is negative.

In the past it was thought that the diagnosis of IBS relied on a diagnosis of exclusion; that is, if one cannot find a cause then IBS is the diagnosis. Currently the diagnosis of IBS relies on meeting Rome II inclusion criteria (updated by Rome III criteria) and excluding other illnesses based on history, physical exam, and laboratory testing. Although the Rome II and III criteria were not designed to be a management guideline, it is currently a "gold standard" for the diagnosis of IBS. Unfortunately, an IBS diagnosis in an adult patient is still only useful as a tool to rule out more serious problems unless further investigation is employed to discern an addressable condition.

[edit] Differential diagnosis

The diagnosis of a functional bowel disorder always presumes the absence of a structural or biochemical explanation for the symptoms. This can be excluded via:

• sigmoidoscopy or colonoscopy
• esophagogastroduodenoscopy (EGD, gastroscopy)
• abdominal ultrasound or CT scan
• blood tests: complete blood count, liver enzymes, electrolytes, renal function, erythrocyte sedimentation rate
• stool chemistry (e.g. tests for exocrine pancreas insufficiency and other malabsorption conditions), stool microbiology, fecal fat
• H₂-tests for lactose intolerance and fructose malabsorption
• blood tests or deep duodenal biopsy for celiac disease

Initial screening only requires a history and physical exam, as well as a full blood count, electrolytes, renal function, and an erythrocyte sedimentation rate. Additional testing is done when there is a poor response to treatment.

While these modalities may be employed to rule out other causes of abdominal symptoms, they are not necessary to make a diagnosis of IBS. Depending on local practice, many doctors avoid overdiagnosing if the history is clearly suggestive of a functional bowel disorder.

Although few doctors will run a complete set of testing, when it is performed the underlying cause of their symptoms can often be found and treated. Testing for bacterial abnormalities, food allergies (IgG type allergies), and parasites are particularly useful though often not covered by insurance and thus not performed.<ref name="TheIrritableBowelSyndromeSolution2006-Wangen>Wangen, Stephen O. The Irritable Bowel Syndrome Solution. 2006. ISBN 0-9768537-8-7. Excerpted with author's permission at The IBS Treatment Center</ref>

[edit] Diagnostic tests

Researchers have demonstrated abnormal sensitivity in IBS patients to intestinal and esophageal distention with balloons. ^{[citation needed]} However, this approach has not yet become available as a diagnostic test since the diagnostic accuracy is low and clinical utility is not yet high enough. The diagnosis of IBS is made by exclusion as there are no serological (blood) markers. A history of major life stress, anxiety, depression, abuse, or preceding infection may be suggestive, yet not diagnostic. Organs outside the gastrointestinal system may be sources of referred symptoms, and abnormalities should be ruled out. Red flags arguing against an IBS diagnosis include bleeding, weight loss, difficulty swallowing, nocturnal symptoms, incontinence, or onset of symptoms over the age of 50. Screening for ruling out colorectal cancer is still applicable.

[edit] Pathophysiology

IBS is highly prevalent in the Western world, but despite the advancement of many theories, no clear cause has yet been established. IBS may a conglomeration of disorders with similar symptoms but multiple different etiologies (root causes). In studies of twins, some <ref name=pmid11606493>Levy R, Jones K, Whitehead W, Feld S, Talley N, Corey L (2001). "Irritable bowel syndrome in twins: heredity and social learning both contribute to etiology.". Gastroenterology 121 (4): 799-804. PMID 11606493.</ref><ref name=pmid17008364>Bengtson MB, Ronning T, Vatn M, Harris J (2006). "IBS in twins: genes and environment.". Gut. PMID 17008364.</ref> but not all studies <ref name=pmid15929767>Mohammed I, Cherkas L, Riley S, Spector T, Trudgill N (2005). "Genetic influences in irritable bowel syndrome: a twin study.". Am J Gastroenterol 100 (6): 1340-4. PMID 15929767.</ref>, a genetic role is found. In the two positive studies, IBS concordance in monozygotic twins is 17% - 22% compared to dizygotic twins having IBS concordance of 8% to 9%. In one of the studies futher support for genetic inflences being a minority contributor, a dizygotic twin with IBS has 15.2% IBS in mothers, compared to 6.7% in their co-twin<ref name=pmid11606493>Levy</ref>. As with many other medical conditions, there is a lot of speculation about causes, including in the field of alternative medicine. Increasing prevalence in developing countries suggests some possible links to diet and cultural factors.<ref name="NeurogastroenterolMoti2005-Gwee">Gwee KA. Irritable bowel syndrome in developing countries—a disorder of civilization or colonization? Neurogastroenterol Motil. 2005 Jun;17(3):317–24. PMID 15916618</ref>

[edit] Visceral hyperalgesia

Evidence of visceral hyperalgesia (increased sensitivity to noxious stimuli in the gut) includes perception of pain from distention of a rectal balloon at smaller volumes than in normal patients <ref name=pmid16401465>Lawal A, Kern M, Sidhu H, Hofmann C, Shaker R (2006). "Novel evidence for hypersensitivity of visceral sensory neural circuitry in irritable bowel syndrome patients.". Gastroenterology 130 (1): 26-33. PMID 16401465.</ref>. However somatic sensitivity testing, such as in controlled pressure on the nails of the hand show that IBS patients have greater pain tolerance than normal patients.

[edit] Post-infectious or post-antibiotic

Onset of IBS after an episodes of enteritis <ref name=pmid16928253>Halvorson H, Schlett C, Riddle M (2006). "Postinfectious irritable bowel syndrome--a meta-analysis.". Am J Gastroenterol 101 (8): 1894-9; quiz 1942. PMID 16928253.</ref> or antibiotics <ref name=pmid11808932>Maxwell P, Rink E, Kumar D, Mendall M (2002). "Antibiotics increase functional abdominal symptoms.". Am J Gastroenterol 97 (1): 104-8. PMID 11808932.</ref> have been described. A meta-analysis found the prevalence of IBS to 9.8% after enteritis as compared to 1.2% in controls <ref name=pmid16928253>Halvorson</ref>. In these cases, a prolonged immune reaction may be the cause. Patients with IBS after a viral illness may have a self limited course of only 3 to 6 months duration..

[edit] Food allergies and sensitivities

Argument continues on the definition of cause as regards IBS and food allergies, but studies demonstrate that IBS symptoms are sometimes caused by immune response to foods and exclusion of those foods to which the immune system is responding results in reduction or elimination of IBS symptoms, a cause and effect link.<ref name="ScandJGastroenterol2005Jul40(7):800–7>Zar S, Mincher L, Benson MJ, Kumar D (2005). "Food-specific IgG4 antibody-guided exclusion diet improves symptoms and rectal compliance in irritable bowel syndrome.". Scandinavian Journal of Gastroenterlogy 40 (7): 800–7. PMID 16109655.</ref>

[edit] Bacterial overgrowth

The intestine is colonised with bacteria (also termed the gut flora). Two studies from the same research group found that 78% to 84% of patients with IBS had bacterial overgrowth. In patients with evidence of bacterial overgrowth, those treated with neomycin had a >/= 35% reduction in clinical response (ie, improvement) compared with an 11% reduction in patients on placebo.<ref name="AmJGastro2000-Pimentel">Pimentel M, Chow EJ, Lin HC (2000). "Eradication of small intestinal bacterial overgrowth reduces symptoms of irritable bowel syndrome". Am J Gastroenterol 95 (12): 3503–6. PMID 11151884.</ref><ref name="AmJGastro2003-Pimentel"> Pimentel M, Chow EJ, Lin HC (2003). "Normalization of lactulose breath testing correlates with symptom improvement in irritable bowel syndrome. a double-blind, randomized, placebo-controlled study". Am J Gastroenterol 98 (2): 412–9. PMID 12591062.</ref> Subsequent studies have also identified significant bacterial overgrowth and demonstrated substantial reduction in symptoms following treatments, especially with antibiotics specific to the strains that are in excess. See section below on treatment with rifaximin.

[edit] Stress

Stress—feeling mentally or emotionally tense, troubled, angry, or overwhelmed—may trigger symptoms in people with IBS. One study found that women with IBS are more likely to report prior physical or sexual abuse; almost half of the patients reported prior abuse <ref name=pmid2240898>Drossman D, Leserman J, Nachman G, Li Z, Gluck H, Toomey T, Mitchell C (1990). "Sexual and physical abuse in women with functional or organic gastrointestinal disorders.". Ann Intern Med 113 (11): 828-33. PMID 2240898.</ref>.

There are various ways that stress may interact with IBS. First, the colon has a vast supply of nerves that connect it to the brain. These nerves control the normal rhythmic contractions of the colon and cause abdominal discomfort at stressful times. People often experience cramps or "butterflies" when they are nervous or upset. But with IBS, the colon can be overly responsive to even slight conflict or stress. Second, some evidence suggests that IBS is affected by the immune system, which fights infection in the body. The immune system is also affected by stress. Third, the link between stress and IBS may be due to socially stressful situations making the mind more tuned to the sensations that arise in the colon and makes the stressed person perceive these sensations as unpleasant.<ref name="NIH2003-IBS"> National Institutes of Health, 2003. Irritable Bowel Syndrome. Publication No. 03–693, April 2003.</ref>

There appears to be an overlap of IBS with stress, chronic pelvic pain, fibromyalgia, chronic fatigue syndrome, the American folk medicine use of term hypoglycaemia, and various mental disorders (in a small minority). While no single explanation for this phenomenon exists, it does strengthen the view that there is a neurological and psychological component to IBS. Recent studies indicate that presynaptic neural effects secondary to the release of histamine (part of immune response) is likely related to these problems.<ref name="Gut2006 - Wood">Wood JD (2006). "Histamine, mast cells, and the enteric nervous system in the irritable bowel syndrome, enteritis, and food allergies". Gut 55: 445–447.</ref>

It should be noted that the gut has its own nervous system - the enteric nervous system which has reciprocal connections to the main brain. The discovery of this system has lead to the development of the field of neurogastroenterology.

For all these reasons, stress management is an important part of treatment for IBS.

[edit] Hormones

The role of hormones in IBS is not yet fully understood. Menstruation frequently triggers or exacerbates IBS symptoms,<ref name="AmJGastro2003-Heitkemper">Heitkemper MM, Cain KC, Jarrett ME, Burr RL, Hertig V, Bond EF (2003). "Symptoms across the menstrual cycle in women with irritable bowel syndrome". Am J Gastroenterol 98 (2): 420–30. PMID 12591063.</ref> while pregnancy and menopause can either worsen or improve symptoms. Hormone replacement therapy is associated with an increased risk of developing IBS.<ref name="Maturitas2003-Ruigomez">Ruigomez A, Garcia Rodriguez LA, Johansson S, Wallander MA (2003). "Is hormone replacement therapy associated with an increased risk of irritable bowel syndrome?". Maturitas 44 (2): 133–40. PMID 12590009.</ref>

[edit] Treatment

One of the most important therapeutic measures is reassuring the patient that they have no fatal or otherwise threatening disease, because this is the major concern of patients seeking medical help. Dietary advice may be given and medication is an option in most forms.

A questionnaire in 2006 designed to identify patients’ perceptions about IBS, their preferences on the type of information they need, as well as educational media and expectations from health care providers, revealed misperceptions about IBS developing into other conditions, including colitis, malnutrition, and cancer.<ref name="JClinGastro2006-Halpert">Halpert AD, Thomas AC, Hu Y, Morris CB, Bangdiwala SI, Drossman DA (2006). "A survey on patient educational needs in irritable bowel syndrome and attitudes toward participation in clinical research". J Clin Gastroenterol 40 (1): 37–43. PMID 16340632.</ref>

The survey found IBS patients were most interested in learning about foods to avoid (60%), causes of IBS (55%), medications (58%), coping strategies (56%), and psychological factors related to IBS (55%). The respondents indicated that they wanted their physician to be available via phone or e-mail following a visit (80%), have the ability to listen (80%), and provide hope (73%) and support (63%).

[edit] Diet

There are a number of dietary changes a person with IBS can make to prevent the overreaction of the gastrocolic reflex and lessen pain, discomfort, and bowel dysfunction. Having soluble fiber foods and supplements, substituting soy or rice products for dairy, being careful with fresh fruits and vegetables that are high in insoluble fiber, and eating regular small amounts, can all help to lessen the symptoms of IBS. Foods and beverages to be avoided or minimized include red meat, oily or fatty and fried products, dairy (even when there is no lactose intolerance), solid chocolate, coffee (regular and decaffeinated), alcohol, carbonated beverages (especially those also containing sorbitol), and artificial sweeteners. However, care should be taken to avoid adding foods to the diet to which the patient is allergic or intolerant.<ref name="EatingForIBS2000-VanVorous">Van Vorous, Heather. Eating for IBS. 2000. ISBN 1-56924-600-9. Excerpted with author's permission at Help for Irritable Bowel Syndrome (see IBS Diet Section)</ref>

Definitive determination of dietary issues can be accomplished by testing for the physiological effects of specific foods. The ELISA food allergy panel can identify specific foods to which a patient has a reaction. Other testing can determine if there are nutritional deficiencies secondary to diet that may also play a role. Removal of foods causing IgG immune response as measured using the ELISA food panel has been shown to substantially decrease symptoms of IBS in several studies.<ref name="Gut2004-Atkinson">Atkinson W, Sheldon TA, Shaath N, Whorwell PJ (2004). "Food elimination based on IgG antibodies in irritable bowel syndrome: a randomised controlled trial". Gut 53 (10): 1459–64. PMID 15361495 Full text.</ref>

There is no evidence that digestion of food or absorption of nutrients is problematic for those with IBS at rates different from those without IBS. However, the very act of eating or drinking can provoke an overreaction of the gastrocolic response in some patients with IBS due to their heightened visceral sensitivity, and this can lead to abdominal pain, diarrhea, and/or constipation.<ref>Sjölund K, Ekman R, Lindgren S, Rehfeld J (1996). "Disturbed motilin and cholecystokinin release in the irritable bowel syndrome.". Scand J Gastroenterol 31 (11): 1110-4. PMID 8938905.</ref>

Several of the most common dietary triggers are well-established by clinical studies at this point; research has shown that IBS patients are hypersensitive to fats and fructose. <ref name="AMJGastro2005-Caldarella">Caldarella MP, Milano A, Laterza F, Sacco F, Balatsinou C, Lapenna D, Pierdomenico SD, Cuccurullo F, Neri M (2005). "Visceral sensitivity and symptoms in patients with constipation- or diarrhea-predominant irritable bowel syndrome (IBS): effect of a low-fat intraduodenal infusion". Am J Gastroenterol 100 (2): 383–9. PMID 15667496.</ref> <ref name="ACG2003-Choi">Choi, Y. Fats, Fructose May Contribute to IBS Symptoms. ACG 68th Annual Scientific Meeting: Abstract 21, presented October 13, 2003; Abstract 547, presented October 14, 2003.</ref>

It also appears that some foods are more difficult for the gut as evidenced by elevated food-specific IgG4 antibodies being present,<ref name="AmJGastro2005-Zar">Zar S, Benson MJ, Kumar D (2005). "Food-specific serum IgG4 and IgE titers to common food antigens in irritable bowel syndrome". Am J Gastroenterol 100 (7): 1550–7. PMID 15984980.</ref> <ref name="ScandJGastro2005-Zar">Zar S, Mincher L, Benson MJ, Kumar D (2005). "Food-specific IgG4 antibody-guided exclusion diet improves symptoms and rectal compliance in irritable bowel syndrome". Scand J Gastroenterol 40 (7): 800–7. PMID 16109655.</ref> while others increase colonic contractions, which may be painful, due to increased visceral sensitivity in IBS sufferers. <ref name="Pain2005-Mayer">Mayer EA, Berman S, Suyenobu B, Labus J, Mandelkern MA, Naliboff BD, Chang L (2005). "Differences in brain responses to visceral pain between patients with irritable bowel syndrome and ulcerative colitis". Pain 115 (3): 398–409. PMID 15911167.</ref>

Fiber

In patients who do not have diarrhea predominant irritable bowel, soluble fiber at does of 20 grams per day can reduce overall symptoms but will not reduce pain. The research supporting dietary fiber contains conflicting, small studies that are complicated by the the heterogeneity of types of fiber and doses used <ref name=pmid14984370>Bijkerk C, Muris J, Knottnerus J, Hoes A, de Wit N (2004). "Systematic review: the role of different types of fibre in the treatment of irritable bowel syndrome.". Aliment Pharmacol Ther 19 (3): 245-51. PMID 14984370.</ref>. The one meta-analysis that controlled for solubility found that only soluble fiber improved global symptoms of irritable bowel and neither type of fiber reduced pain <ref name=pmid14984370>.</ref>. Positive studies have used 20-30 grams per day of psyllium seed (also called ispaghula husk)<ref name=pmid3322956>Prior A, Whorwell P (1987). "Double blind study of ispaghula in irritable bowel syndrome.". Gut 28 (11): 1510-3. PMID 3322956.</ref> <ref name=pmid2129822>Jalihal A, Kurian G. "Ispaghula therapy in irritable bowel syndrome: improvement in overall well-being is related to reduction in bowel dissatisfaction.". J Gastroenterol Hepatol 5 (5): 507-13. PMID 2129822.</ref>. One study specifically examined the effect of dose and found that 20 grams of ispaghula husk was better than 10 grams and equivalent to 30 grams per day <ref name=pmid3030900>Kumar A, Kumar N, Vij J, Sarin S, Anand B (1987). "Optimum dosage of ispaghula husk in patients with irritable bowel syndrome: correlation of symptom relief with whole gut transit time and stool weight.". Gut 28 (2): 150-5. PMID 3030900.</ref>An uncontrolled study noted increased symptoms with insoluble fibers. <ref name="BranIBS1994-Francis">Francis CY, Whorwell PJ (1994). "Bran and irritable bowel syndrome: time for reappraisal". Lancet 344 (8914): 39–40. PMID 7912305.</ref> It is unclear if these symptoms are truly increased compared to a control group. If the symptoms are increased, it is unclear if these patients were diarrhea predominant (which can be exacerbated by fiber <ref name=pmid6365490>Cann P, Read N, Holdsworth C, Barends D (1984). "Role of loperamide and placebo in management of irritable bowel syndrome (IBS).". Dig Dis Sci 29 (3): 239-47. PMID 6365490.</ref><ref name=pmid6319244>Cann P, Read N, Holdsworth C (1984). "What is the benefit of coarse wheat bran in patients with irritable bowel syndrome?". Gut 25 (2): 168-73. PMID 6319244.</ref>), or if the increase is temporary before benefit occurs.

[edit] Medication

[edit] Initial treatments

Medications may consist of stool softeners and laxatives in constipation-predominant IBS, and antidiarrheals (e.g., opioid or opioid analogs such as loperamide (Imodium®), or diphenoxylate (Lomotil®)) in diarrhea-predominant IBS for mild symptoms<ref name=pmid15846668>Quartero A, Meineche-Schmidt V, Muris J, Rubin G, de Wit N. "Bulking agents, antispasmodic and antidepressant medication for the treatment of irritable bowel syndrome.". Cochrane Database Syst Rev: CD003460. PMID 15846668.</ref><ref name=pmid15606387>Lesbros-Pantoflickova D, Michetti P, Fried M, Beglinger C, Blum A (2004). "Meta-analysis: The treatment of irritable bowel syndrome.". Aliment Pharmacol Ther 20 (11-12): 1253-69. PMID 15606387.</ref><ref name=pmid10896640>Jailwala J, Imperiale T, Kroenke K (2000). "Pharmacologic treatment of the irritable bowel syndrome: a systematic review of randomized, controlled trials.". Ann Intern Med 133 (2): 136-47. PMID 10896640.</ref>.

Anti-diarrheal agents

Randomized controlled trials have shown loperamide reduces diarrhea with an inconsistent effect on pain <ref name=pmid8734343>Efskind P, Bernklev T, Vatn M (1996). "A double-blind placebo-controlled trial with loperamide in irritable bowel syndrome.". Scand J Gastroenterol 31 (5): 463-8. PMID 8734343.</ref>.

Laxatives

Regarding laxatives for patients who do not adequately respond to fiber, osmotic agents (polyethylene glycol, sorbitol, and lactulose) are good choices in order to avoid 'cathartic colon' which has been associated with stimulant laxatives <ref name=pmid9649012>Joo J, Ehrenpreis E, Gonzalez L, Kaye M, Breno S, Wexner S, Zaitman D, Secrest K (1998). "Alterations in colonic anatomy induced by chronic stimulant laxatives: the cathartic colon revisited.". J Clin Gastroenterol 26 (4): 283-6. PMID 9649012.</ref>. Among the osmotic laxatives, a randomized controlled trial found greater improvement from 2 sachets (26 grams) of polyethylene glycol (PEG) versus or 2 sachets (20 grams) of lactulose <ref name=pmid9895382>Attar A, Lémann M, Ferguson A, Halphen M, Boutron M, Flourié B, Alix E, Salmeron M, Guillemot F, Chaussade S, Ménard A, Moreau J, Naudin G, Barthet M (1999). "Comparison of a low dose polyethylene glycol electrolyte solution with lactulose for treatment of chronic constipation.". Gut 44 (2): 226-30. PMID 9895382.</ref>. Another randomized controlled trial found no difference between sorbitol and lactulose <ref name=pmid2122724>Lederle F, Busch D, Mattox K, West M, Aske D (1990). "Cost-effective treatment of constipation in the elderly: a randomized double-blind comparison of sorbitol and lactulose.". Am J Med 89 (5): 597-601. PMID 2122724.</ref>.

Antispasmodics

The use of antispasmodic drugs (e.g. anticholinergics such as hyoscine) may help patients, especially those with cramps or diarrhea. A meta-analysis by the Cochrane Collaboration concludes that if 6 patients are treated with antispasmodics, 1 patient will benefit (number needed to treat = 6)<ref name=pmid15846668 >used</ref>. Antispasmodic drugs are also available in combination with tranquilizers or barbiturates, such as Librax® (chlordiazepoxide and clidinium) and Donnatal® (mixed salts of belladonna alkaloids and phenobarbital), respectively. However, the value of the combination therapies is not clear as the role of tranquilizers is not established.

[edit] Drugs affecting serotonin (5-HT)

Drugs affecting serotonin (5-HT) in the intestines can help reduce symptoms<ref name=pmid11755632>Talley N (2001). "Serotoninergic neuroenteric modulators.". Lancet 358 (9298): 2061-8. PMID 11755632.</ref>. Serotonin stimulates the gut motility and so agonists can help constipation predominate irritable bowel while antagonists can help diarrhea predominant irritable bowel:

Agonists

• Tegaserod, a selective 5-HT4 agonist for IBS-C, is available for relieving IBS constipation in women and chronic idiopathic constipation in men and women. The USA FDA has issued two warnings about the serious consequences of Tegaserod. In 2005, Tegaserod was rejected as an IBS medication by the European Union; however, it is available in some other countries, including the United States. Tegaserod, marketed as Zelnorm in the United States, is the only agent approved to treat the multiple symptoms of IBS (in women only), including constipation, abdominal pain and bloating. A meta-analysis by the Cochrane Collaboration concludes that if 17 patients are treated with typical doses of tegaserod, 1 patient will benefit (number needed to treat = 17) <ref name=pmid14974049>Evans B, Clark W, Moore D, Whorwell P. "Tegaserod for the treatment of irritable bowel syndrome.". Cochrane Database Syst Rev: CD003960. PMID 14974049.</ref>.
• Selective serotonin reuptake inhibitor anti-depressants (SSRIs), because of their serotonergic effect, would seem to help IBS, especially patients who are constipation predominant. Initial crossover studies <ref name=pmid16401691>Tack J, Broekaert D, Fischler B, Oudenhove L, Gevers A, Janssens J (2006). "A controlled crossover study of the selective serotonin reuptake inhibitor citalopram in irritable bowel syndrome.". Gut 55 (8): 1095-103. PMID 16401691.</ref> and randomized controlled trials <ref name=pmid16128675>Vahedi H, Merat S, Rashidioon A, Ghoddoosi A, Malekzadeh R (2005). "The effect of fluoxetine in patients with pain and constipation-predominant irritable bowel syndrome: a double-blind randomized-controlled study.". Aliment Pharmacol Ther 22 (5): 381-5. PMID 16128675.</ref> <ref name=pmid12557136>Creed F, Fernandes L, Guthrie E, Palmer S, Ratcliffe J, Read N, Rigby C, Thompson D, Tomenson B (2003). "The cost-effectiveness of psychotherapy and paroxetine for severe irritable bowel syndrome.". Gastroenterology 124 (2): 303-17. PMID 12557136.</ref> <ref name=>Tabas G, Beaves M, Wang J, Friday P, Mardini H, Arnold G (2004). "Paroxetine to treat irritable bowel syndrome not responding to high-fiber diet: a double-blind, placebo-controlled trial.". Am J Gastroenterol 99 (5): 914-20. PMID 15128360.</ref> support this role.

Antagonists

• Alosetron, a selective 5-HT3 antagonist for IBS-D, which is only available for women in the United States under a restricted access program, due to severe risks of side-effects if taken mistakenly by IBS-A or IBS-C sufferers.
• Cilansetron, also a selective 5-HT3 antagonist, is undergoing further clinical studies in Europe for IBS-D sufferers. In 2005, Solvay Pharmaceuticals withdrew Cilansetron from the United States regulatory approval process after receiving a "not approvable" action letter from the FDA requesting additional clinical trials.

[edit] Other agents

Anti-depressents include both tricyclic antidepressants (TCAs) and the newer selective serotonin reuptake inhibitors (SSRIs). In addition to improving symptoms via treating any co-existing depression, TCAs have anti-cholinergic actions while SSRIs are serotonergic. Thus in theory, TCAs would best treat diarrhea-predominant IBS while SSRIs would best treat constipation-predominant IBS. A meta-analysis of randomized controlled trials of mainly TCAs found 3 patients have to be treated with TCAs for one patient to improve (number needed to treat = 3)<ref name=pmid11059442>Jackson J, O'Malley P, Tomkins G, Balden E, Santoro J, Kroenke K (2000). "Treatment of functional gastrointestinal disorders with antidepressant medications: a meta-analysis.". Am J Med 108 (1): 65-72. PMID 11059442.</ref>. A separate randomzied controlled trial found that TCAs are best for patients with diarrhea-predominant IBS <ref name=pmid12851867>Drossman D, Toner B, Whitehead W, Diamant N, Dalton C, Duncan S, Emmott S, Proffitt V, Akman D, Frusciante K, Le T, Meyer K, Bradshaw B, Mikula K, Morris C, Blackman C, Hu Y, Jia H, Li J, Koch G, Bangdiwala S (2003). "Cognitive-behavioral therapy versus education and desipramine versus placebo for moderate to severe functional bowel disorders.". Gastroenterology 125 (1): 19-31. PMID 12851867.</ref>. SSRIs are discussed above under 'Drugs affecting serotonin'.

Recent studies have suggested that rifaximin, a non-absorbable antibiotic, can be used as an effective treatment for abdominal bloating and flatulence <ref name="AmJGastro2006-Sharara"> Sharara AI, Aoun E, Abdul-Baki H, Mounzer R, Sidani S, Elhajj I (2006). "A randomized double-blind placebo-controlled trial of rifaximin in patients with abdominal bloating and flatulence". Am J Gastroenterol 101 (2): 326–33. PMID 16454838.</ref><ref name=pmid17043337>Pimentel M, Park S, Mirocha J, Kane S, Kong Y (2006). "The effect of a nonabsorbed oral antibiotic (rifaximin) on the symptoms of the irritable bowel syndrome: a randomized trial.". Ann Intern Med 145 (8): 557-63. PMID 17043337.</ref>, giving more credibility to the potential role of bacterial overgrowth in some patients with IBS <ref name="AmJGastro2006-Quigley"> Quigley EM (2006). "Germs, gas and the gut; the evolving role of the enteric flora in IBS". Am J Gastroenterol 101 (2): 334–5. PMID 16454839.</ref>.

Enteric coated peppermint oil capsules has been advocated for IBS symptoms in adults and children <ref name="AmFamPhysician2005-Hadley">Hadley SK, Gaarder SM (2005). "Treatment of irritable bowel syndrome". Am Fam Physician 72 (12): 2501–6. PMID 16370407.</ref>; however, results from trials have been inconsistent <ref name=pmid3527248>Nash P, Gould S, Bernardo D (1986). "Peppermint oil does not relieve the pain of irritable bowel syndrome.". Br J Clin Pract 40 (7): 292-3. PMID 3527248.</ref> <ref name=pmid9430014>Liu J, Chen G, Yeh H, Huang C, Poon S (1997). "Enteric-coated peppermint-oil capsules in the treatment of irritable bowel syndrome: a prospective, randomized trial.". J Gastroenterol 32 (6): 765-8. PMID 9430014.</ref>. Peppermint may exacerbate gastroesophageal reflux disease.

For severe diarrhea-predominant IBS, more potent opioids may be used, such as codeine or propoxyphene (Darvon®); refractory cases may even be treated with paregoric, or, more rarely, deodorized tincture of opium or morphine sulfate. The use of opioids remains controversial due to the lack of evidence supporting their benefit and the potential risk of tolerance, physical dependence and psychological dependence (addiction).

Cannabis has theoretical support for its role <ref name=pmid16133420>Massa F, Storr M, Lutz B (2005). "The endocannabinoid system in the physiology and pathophysiology of the gastrointestinal tract.". J Mol Med 83 (12): 944-54. PMID 16133420.</ref><ref name=pmid15159679>Russo E. "Clinical endocannabinoid deficiency (CECD): can this concept explain therapeutic benefits of cannabis in migraine, fibromyalgia, irritable bowel syndrome and other treatment-resistant conditions?". Neuro Endocrinol Lett 25 (1-2): 31-9. PMID 15159679.</ref>, but has not been subject of clinical studies. Although illegal in the United States, it has been prescribed to patients in nations such as Canada. Some of the argued benefits of cannabis are the reduction of pain and nausea, appetite stimulation, and assisting in falling sleep.

[edit] Psychotherapy and hypnotherapy

There is a strong brain-gut component to IBS, and cognitive therapy may improve symptoms in a proportion of patients in conjunction with antidepressants <ref name="BMJ2005-Kennedy">Kennedy T, Jones R, Darnley S, Seed P, Wessely S, Chalder T (2005). "Cognitive behaviour therapy in addition to antispasmodic treatment for irritable bowel syndrome in primary care: randomised controlled trial". BMJ 331 (7514): 435. PMID 16093252 Full text.</ref>. In a randomized controlled trial of referred patients, cognitive behavioral therapy helped even though patients in this study did not have any psychiatric diagnoses <ref name=pmid10763948>Heymann-Mönnikes I, Arnold R, Florin I, Herda C, Melfsen S, Mönnikes H (2000). "The combination of medical treatment plus multicomponent behavioral therapy is superior to medical treatment alone in the therapy of irritable bowel syndrome.". Am J Gastroenterol 95 (4): 981-94. PMID 10763948.</ref>.

Gut-directed or gut-specific hypnotherapy or self-hypnosis is one of the most promising areas of IBS treatment. Current research shows that symptom reduction/elimination from IBS hypnotherapy can last at least five years <ref name="Gut2003-Gonsalkorale"> Gonsalkorale WM, Miller V, Afzal A, Whorwell PJ (2003). "Long term benefits of hypnotherapy for irritable bowel syndrome". Gut 52 (11): 1623–9. PMID 14570733.</ref>.

[edit] Alternative treatments

Probiotics

Probiotics are generally accepted to be potentially beneficial strains of bacteria and yeast, often found in the human gut. One research study has shown a clear link between the ingestion of Lactobacillus plantarum LP299V and sufferers of IBS who reported resolution of their abdominal pain <ref name="EurJGastroHepatol2001-Niedzielin"> Niedzielin K, Kordecki H, Birkenfeld B (2001). "A controlled, double-blind, randomized study on the efficacy of Lactobacillus plantarum 299V in patients with irritable bowel syndrome". Eur J Gastroenterol Hepatol 13 (10): 1143–7. PMID 11711768.</ref>. Another study showed the utility of B. infantis 35625, a strain of Bifidobacteria in normalizing bowel movement frequency in sufferers of IBS <ref name="AmColGastro2005-StudiesProbiotics">New Studies Examine the Evidence of Probiotics on IBS (Oct 2005). American College of Gastrointerologists. Retrieved on March 2, 2006</ref>. Some practitioners of Integrative Medicine, now recommend a strain of Lactobacillus known commonly as "LGG" after its discoverers Gorbach and Goldin. This strain in particular has shown an ability to endure the acidic environment of the stomach and survive until presentation to the intestinal tract <ref name="EaseThePain2006-Weil">Ease the pain of IBS, (2006). Andrew Weil. Retrieved on March 2, 2006</ref>.

Acupuncture

Many sufferers of IBS seek relief using Acupuncture, a component of Traditional Chinese Medicine. The meta-analysis by the Cochrane Collaboration concluded 'Most of the trials included in this review were of poor quality and were heterogeneous in terms of interventions, controls, and outcomes measured. With the exception of one outcome in common between two trials, data were not combined. Therefore, it is still inconclusive whether acupuncture is more effective than sham acupuncture or other interventions for treating IBS'<ref name=pmid17054239>Lim B, Manheimer E, Lao L, Ziea E, Wisniewski J, Liu J, Berman B. "Acupuncture for treatment of irritable bowel syndrome.". Cochrane Database Syst Rev: CD005111. PMID 17054239.</ref>. One practitioner of Tradtional Chinese Medicine asserts that IBS has become a bit of a "garbage diagnosis" for some medical practitioners. Traditional Chinese Medicine does not recognize the Western diagnosis of IBS per se, as the named condition has no definitive single test for diagnosis, clear cause, or cure. Traditional Chinese Medicine approaches IBS on an individual symptom-by-symptom basis, rather than recognizing a standard "IBS" diagnosis, which then warrants a blanket "IBS" treatment <ref name="IBSTCM2006-Stone"> Irritable Bowel Syndrome - A Traditional Chinese Medicine Perspective, (2006). Al Stone L.Ac. Retrieved on February 14, 2006.</ref>. According to the National Institutes of Health, "Preclinical studies have documented acupuncture's effects, but they have not been able to fully explain how acupuncture works within the framework of the Western system of medicine that is commonly practiced in the United States." <ref name="NCCAM2006-Acupuncture">Get the Facts, Acupuncture, (2006). National Institute of Health. Retrieved on March 2, 2006.</ref>.

[edit] Epidemiology

Point prevalence is 10-20% of the general population of Western countries with a much higher lifetime prevalence. Prevalence is similar in India, Japan, and China. IBS is less common in Thailand and rural South African areas. In Western countries, but not in India or Sri Lanka, females have a greater risk of developing IBS.

Of the persons who have symptoms of IBS, only a proportion seeks medical help. However, there is not yet a predictor known for who will seek medical help and who will not.

[edit] Prognosis

IBS is not fatal nor is it linked to the development of other serious bowel diseases. However, due to the chronic pain, discomfort, and other symptoms, work absenteeism, social phobias, and other negative quality-of-life effects can be common in more serious cases. Individuals who find a caring primary caregiver and/or sufficient self-help options should be able to develop a successful treatment program for their symptoms and lead normal lives.

[edit] References

[edit] External links

• Rome II Diagnostic Criteria for the Functional Gastrointestinal Disorders
• Irritable bowel syndrome at informedhealthonline.org

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es:Síndrome irritable de intestinos fr:Côlon irritable he:תסמונת המעי הרגיז nl:Prikkelbare-darmsyndroom pl:Zespół jelita drażliwego pt:Síndrome do cólon irritável sv:IBS