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Irritable bowel syndrome

  • Overview
  • Theory
  • Diagnosis
  • Management
  • Follow up
  • Resources
Last reviewed: 4 Aug 2025
Last updated: 01 Nov 2023

Summary

Definition

History and exam

Key diagnostic factors

  • abdominal pain
  • alteration of bowel habits associated with pain
  • abdominal bloating or distension
  • normal exam of abdomen
Full details

Other diagnostic factors

  • passage of mucus with stool
  • urgency of defecation
Full details

Risk factors

  • physical and sexual abuse
  • posttraumatic stress disorder (PTSD)
  • age <50 years
  • female sex
  • previous enteric infection
  • family history
  • family and job stress
Full details

Diagnostic tests

1st tests to order

  • CBC
Full details

Tests to consider

  • fecal occult blood test
  • quantitative fecal immunochemical test (FIT)
  • serologic tests for celiac disease
  • fecal calprotectin
  • fecal lactoferrin
  • serum C-reactive protein (CRP)
  • erythrocyte sedimentation rate (ESR)
  • serum fibroblast growth factor 19
  • 23‐seleno‐25‐homotaurocholic acid (SeHCAT) test
  • 48-hour stool collection for total bile acids
  • empiric trial of bile acid binder
  • hydrogen/methane breath test
  • stool tests for Giardia lamblia
  • plain abdominal radiograph
  • colonoscopy
  • flexible sigmoidoscopy
Full details

Treatment algorithm

ONGOING

constipation-predominant

diarrhea-predominant

alternating constipation and diarrhea

Contributors

Authors

Ned Snyder, MD, MACP, AGAF

Professor of Medicine

Baylor College of Medicine and Marion DeBakey VA Hospital

Houston

TX

Adjunct Professor of Medicine

University of Texas Medical Branch

Galveston

TX

Disclosures

NS declares that he is a member on the board of the Kelsey Research Foundation, a non-profit organization. Kelsey Research Foundation has received and awarded private grants for the study of the microbiome in several diseases, including irritable bowel syndrome.

Peer reviewers

Douglas Drossman, MD

Professor of Medicine and Psychiatry

School of Medicine

Co-Director

UNC Center for Functional GI and Motility Disorders

Chapel Hill

NC

Disclosures

DD declares that he has no competing interests.

Simon McLaughlin, MBBS

Research Fellow

Department of Gastroenterology

St Mark's Hospital

Northwick Park

Harrow

UK

Disclosures

SM declares that he has no competing interests.

Horace Williams, MBBS

Clinical Research Fellow

Division of Medicine

Imperial College

London

UK

Disclosures

HW declares that he has no competing interests.

Peer reviewer acknowledgements

BMJ Best Practice topics are updated on a rolling basis in line with developments in evidence and guidance. The peer reviewers listed here have reviewed the content at least once during the history of the topic.

Disclosures

Peer reviewer affiliations and disclosures pertain to the time of the review.

References

Our in-house evidence and editorial teams collaborate with international expert contributors and peer reviewers to ensure that we provide access to the most clinically relevant information possible.

Key articles

Longstreth GF, Thompson WG, Chey WD, et al. Functional bowel disorders. Gastroenterology. 2006 Apr;130(5):1480-91.Full text  Abstract

Lacy BE, Pimentel M, Brenner DM, et al. ACG clinical guideline: management of irritable bowel syndrome. Am J Gastroenterol. 2021 Jan 1;116(1):17-44.Full text  Abstract

Smalley W, Falck-Ytter C, Carrasco-Labra A, et al. AGA clinical practice guidelines on the laboratory evaluation of functional diarrhea and diarrhea-predominant irritable bowel syndrome in adults (IBS-D). Gastroenterology. 2019 Sep;157(3):851-4.Full text  Abstract

Chey WD, Hashash JG, Manning L, et al. AGA clinical practice update on the role of diet in irritable bowel syndrome: expert review. Gastroenterology. 2022 May;162(6):1737-45.e5.Full text  Abstract

Dionne J, Ford AC, Yuan Y, et al. A systematic review and meta-analysis evaluating the efficacy of a gluten-free diet and a low FODMAPs diet in treating symptoms of irritable bowel syndrome. Am J Gastroenterol. 2018 Sep;113(9):1290-300. Abstract

Chang L, Sultan S, Lembo A, et al. AGA clinical practice guideline on the pharmacological management of irritable bowel syndrome with constipation. Gastroenterology. 2022 Jul;163(1):118-36.Full text  Abstract

Lembo A, Sultan S, Chang L, et al. AGA clinical practice guideline on the pharmacological management of irritable bowel syndrome with diarrhea. Gastroenterology. 2022 Jul;163(1):137-51.Full text  Abstract

Reference articles

A full list of sources referenced in this topic is available to users with access to all of BMJ Best Practice.

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  • Patient information

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