What's New in Updated BSG Guidelines on Managing Irritable Bowel Syndrome?

Dawn O'Shea

May 04, 2021

The British Society of Gastroenterology has published new guidelines on the management of irritable bowel syndrome (IBS). Here's a summary of the key recommendations:


  • The National Institute for Health and Care Excellence (NICE) guideline definition of IBS (abdominal pain or discomfort association with altered bowel habit for six months or more, in the absence of alarm symptoms or signs) may be more applicable to primary care than secondary care.

  • Patients presenting to primary care for the first time with symptoms of IBS should have the following tests:

    • Full blood count.

    • C reactive protein or erythrocyte sedimentation rate.

    • Coeliac serology.

    • Faecal calprotectin in patients <45 years of age with diarrhoea, to exclude inflammatory bowel disease.

  • Referral to gastroenterology is warranted where there is diagnostic doubt, severe symptoms or inadequate response to first-line treatments.

  • There is no role for colonoscopy in the absence of alarm symptoms/signs or symptoms suggestive of IBS with diarrhoea who have atypical features and/or relevant risk factors that increase the likelihood of them having microscopic colitis:

    • Female sex.

    • Age ≥50 years.

    • Coexistent autoimmune disease.

    • Nocturnal or severe, watery, diarrhoea.

    • Duration of diarrhoea <12 months.

    • Weight loss or use of potential precipitating drugs including non-steroidal anti-inflammatory drugs and proton pump inhibitors.

  • For IBS with diarrhoea and atypical features such as nocturnal diarrhoea or prior cholecystectomy, 23-seleno-25-homotaurocholic acid scanning or serum 7α-hydroxy-4-cholesten-3-one should be considered to exclude bile acid diarrhoea.

  • In patients with symptoms suggestive of a defaecatory disorder or faecal incontinence, anorectal physiology tests can be considered.

  • In patients with typical IBS symptoms, there is no role for exocrine pancreatic insufficiency or for hydrogen breath testing.

First-line treatments

  • Exercise and dietary advice.

  • Food elimination diets based on immunoglobulin G antibodies are not recommended.

  • Soluble fibre, such as ispaghula, is effective but insoluble fibre should be avoided. Soluble fibre should be commenced at 3-4 g/day and built up gradually to avoid bloating.

  • A diet low in fermentable oligosaccharides, disaccharides and monosaccharides and polyols can be considered as second-line dietary therapy.

  • A gluten-free diet is not recommended in IBS.

  • Probiotics may be effective but no specific species or strains are recommended. Probiotics should be trialled for ≤12 weeks.

  • Other therapies to consider:

Second-line treatments

  • Tricyclic antidepressants or selective serotonin reuptake inhibitors as gut-brain neuromodulators, commenced at a low dose (e.g. 10 mg amitriptyline once a day, titrated slowly to a maximum of 30-50 mg once daily).

  • Eluxadoline (mu-opioid receptor agonist) is effective for diarrhoea in secondary care. Contraindicated in patients with prior sphincter of Oddi problems or cholecystectomy, alcohol dependence, pancreatitis or severe liver impairment.

  • 5-hydroxytryptamine 3 receptor antagonists likely the most efficacious for IBS with diarrhoea in secondary care, e.g., alosetron and ramosetron. Titrate ondansetron from 4 mg once daily to a maximum of 8 mg three times a day.

  • Consider rifaximin for IBS with diarrhoea in secondary care, although its effect on abdominal pain is limited.

  • Linaclotide, a guanylate cyclase-C agonist, is likely to be the most efficacious secretagogue available for IBS with constipation.

  • Lubiprostone is less likely to cause diarrhoea than other chloride channel activator.

  • Plecanatide is efficacious for IBS with constipation in secondary care. Diarrhoea is no less likely than with linaclotide or tenapanor.

  • Tenapanor and tegaserod are effective for IBS with constipation in secondary care.

Psychological therapies

  • Psychological therapies should be considered when symptoms have not improved after 12 months of drug treatment.

  • IBS-specific cognitive behavioural therapy and gut-directed hypnotherapy many be effective.

Management of severe or refractory IBS

  • Review diagnosis.

  • Managed with an integrated multi-disciplinary approach.

  • Iatrogenic harms due to opioid prescribing, unnecessary surgery and unproven unregulated diagnostic or therapeutic approaches incentivised by financial or reputational gain should be avoided.

  • Use of combination gut-brain neuromodulators may be considered for more severe symptoms, with vigilance for risks of serotonin syndrome.

The full guidelines are published in  Gut .


Vasant DH, Paine PA, Black CJ, Houghton LA, Everitt HA, Corsetti M, Agrawal A, Aziz I, Farmer AD, Eugenicos MP, Moss-Morris R, Yiannakou Y, Ford AC. British Society of Gastroenterology guidelines on the management of irritable bowel syndrome. Gut. 2021 Apr 26 [Epub ahead of print]. doi: 10.1136/gutjnl-2021-324598. PMID: 33903147.

This article originally appeared on Univadis, part of the Medscape Professional Network.


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