Clinical Notes : Gastroenterology

130. Irritable Bowel Syndrome in Adults

130. IBS.jpg

Irritable Bowel Syndrome in Adults




A diagnosis of IBS should be considered only if the person has abdominal pain or discomfort that is either relieved by defecation or associated with altered bowel frequency or stool form.

This should be accompanied by at least two of the following four symptoms :

  • altered stool passage (straining, urgency, incomplete evacuation)

  • abdominal bloating (more common in women than men), distension, tension or hardness

  • symptoms made worse by eating

  • passage of mucus

Other features such as lethargy, nausea, backache and bladder symptoms are common in people with IBS, and may be used to support the diagnosis


In people who meet the IBS diagnostic criteria, the following tests should be undertaken to exclude other diagnoses :

  • full blood count (FBC)

  • erythrocyte sedimentation rate (ESR) or plasma viscosity

  • c‑reactive protein (CRP)

  • antibody testing for coeliac disease (endomysial antibodies [EMA] or tissue transglutaminase [TTG]).

The following tests are not necessary to confirm diagnosis in people who meet the IBS diagnostic criteria :

  • ultrasound

  • rigid/flexible sigmoidoscopy

  • colonoscopy; barium enema

  • thyroid function test

  • faecal ova and parasite test

  • faecal occult blood

  • hydrogen breath test (for lactose intolerance and bacterial overgrowth).


Dietary and Lifestyle advice

Assess diet and nutrition, with he following general advice given.

  • Have regular meals and take time to eat.

  • Avoid missing meals or leaving long gaps between eating.

  • Drink at least 8 cups of fluid per day, especially water or other non‑caffeinated drinks, for example herbal teas.

  • Restrict tea and coffee to 3 cups per day.

  • Reduce intake of alcohol and fizzy drinks.

  • It may be helpful to limit intake of high‑fibre food (such as wholemeal or high‑fibre flour and breads, cereals high in bran, and whole grains such as brown rice).

  • Reduce intake of 'resistant starch' (starch that resists digestion in the small intestine and reaches the colon intact), which is often found in processed or re‑cooked foods.

  • Limit fresh fruit to 3 portions per day (a portion should be approximately 80 g).

  • People with diarrhoea should avoid sorbitol, an artificial sweetener found in sugar‑free sweets (including chewing gum) and drinks, and in some diabetic and slimming products.

  • People with wind and bloating may find it helpful to eat oats (such as oat‑based breakfast cereal or porridge) and linseeds (up to 1 tablespoon per day).


Review the fibre intake of people with IBS, adjusting (usually reducing) it while monitoring the effect on symptoms.

People with IBS should be discouraged from eating insoluble fibre (for example, bran).

If an increase in dietary fibre is advised, it should be soluble fibre such as ispaghula powder or foods high in soluble fibre (for example, oats)

People with IBS who choose to try probiotics should be advised to take the product for at least 4 weeks while monitoring the effect. Probiotics should be taken at the dose recommended by the manufacturer.

If a person's IBS symptoms persist while following general lifestyle and dietary advice, refer to a healthcare professional with expertise in dietary management for advice on single food avoidance and exclusion diets (for example, a low FODMAP [fermentable oligosaccharides, disaccharides, monosaccharides and polyols] diet)​

People with low activity levels should be given brief advice and counselling to encourage them to increase their activity levels

Pharmacological therapy.

Decisions about pharmacological management should be based on the nature and severity of symptoms.

  • Antispasmodics

    • taken as required, alongside dietary and lifestyle advice.

    • e.g. Mebeverine, Hyoscine butylbromide


  • Laxatives

    • e.g. Sennoside B

    • avoid lactulose

  • Antimotility agent for diarrhoea

    • e.g. loperamide

People with IBS should be advised how to adjust their doses of laxative or antimotility agent according to the clinical response.

The dose should be titrated according to stool consistency, with the aim of achieving a soft, well‑formed stool

  • Antidepressants

    • second‑line treatment for people with IBS if laxatives, loperamide or antispasmodics have not helped

    • first choice : tricyclic antidepressants (TCAs)

      • Start treatment at a low dose (5–10 mg equivalent of amitriptyline), taken once at night, and review regularly. Increase the dose if needed, but not usually beyond 30 mg

    • second choice :serotonin reuptake inhibitors (SSRIs)

      • only if TCAs are ineffective

Other therapies

  • Referral for psychological interventions

    • for people with IBS who do not respond to pharmacological treatments after 12 months and who develop a continuing symptom profile (described as refractory IBS)

      • cognitive behavioural therapy [CBT]

      • hypnotherapy

      • psychological therapy

  • acupuncture should not be encouraged for the treatment of IBS

  • reflexology should not be encouraged for the treatment of IBS


1. Irritable Bowel Syndrome in Adults : diagnosis and management

NICE, National Institute for Health and Care Excellence

Guideline CG61, April 2017


Guidelines for the investigation of chronic diarrhoea in adults

British Society of Gastroenterology



Irritable bowel syndrome diagnosis and management: a simplified algorithm for clinical practice

United European Gastroenterology Journal



Diagnosis and treatment of irritable bowel syndrome

Danish Society for Gastroenterology and Hepatology



Management of irritable bowel syndrome and chronic idiopathic constipation

American College of Gastroenterology



Irritable bowel syndrome

BMJ Best Practice

February 2019


BMJ Best Practice.png
Ireland notes.png

Mebeverine is available in Ireland as Colofac

Hyoscine butylbromide is available in Ireland as Buscopan

Sennoside is available in Ireland as Sennokot

Loperamide is available in Ireland as Imodium


CPD Quiz and Certificate

This activity attracts 1,0 CPD point

130. IBS.jpg

Scroll down the box above to view its entire content

All users who successfully complete the quiz are e-mailed a copy of their personalised CPD certificate.