Irritable bowel syndrome guidance

This guidance is largely based on NICE Guideline CG61: Irritable bowel syndrome in adults: diagnosis and management (updated April 2017); it has been developed in collaboration with local specialists.

For diagnosis and referral advice, see the Irritable Bowel Syndrome/Inflammatory Bowel Disease clinical referral guideline. Note: The pre-referral criteria contained within this guidance is applicable to Western locality patients only.

Dietary and lifestyle advice

The British Dietetic Association (BDA) has produced a useful IBS food fact sheet.

Encourage people with IBS to identify and make the most of their leisure time, and to create relaxation time. People with low physical activity levels should be encouraged to increase their physical activity where appropriate.

People with IBS should be advised to:

  • Have regular meals and take time to eat
  • Avoid missing meals or leaving long gaps between eating
  • Drink at least 8 cups of non-caffeinated drinks per day
  • Restrict tea and coffee to 3 cups per day
  • Reduce intake of alcohol and fizzy drinks
  • Limit high-fibre foods (wholemeal/high-fibre flour/bread, bran, brown rice etc.)
  • Reduce intake of 'resistant starch' (found in processed or re-cooked foods)
  • Limit fresh fruit to 3 portions per day (1 portion = approx. 80g)

People with diarrhoea should be advised to avoid sorbitol.

People with wind and bloating may find it helpful to eat oats (cereal/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 (e.g. bran). If an increase in dietary fibre is advised, it should be soluble fibre (e.g. ispaghula powder) or foods high in soluble fibre (e.g. oats).

If symptoms persist, consider referral for a trial low FODMAP diet (specialist dietetic input).

Aloe vera

The use of Aloe vera in the treatment of IBS should be discouraged. Aloe vera has been shown to be of no benefit in IBS compared to placebo. Potentially serious adverse effects are associated with aloe vera preparations including an increase in risk of dehydration and electrolyte imbalance when taken with laxative drugs, lowering of potassium levels and possible lowering of blood sugar.

Pharmacological management of symptoms

Decisions about drug treatment should be based on the nature and severity of symptoms. The following recommendations assume that the choice of single or combination medication is determined by the predominant symptom(s).

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 (corresponding to Bristol Stool Form Scale type 4).

Pain and spasm

Consider antispasmodics, to be taken when required, alongside dietary and lifestyle advice.

  • 135mg three times daily
  • Preferably taken 20 minutes before meal
Hyoscine butylbromide
  • 10mg three times daily, increased if required up to 20mg four times daily

See section 1.2 Antispasmodics and other drugs altering gut motility


Doses should be adjusted according to response. Avoid lactulose in patients with IBS.

Ispaghula husk
  • Usually 1 sachet twice daily, in at least 300ml of water, preferably after meals
  • Sufficient fluid intake is important in patients taking ispaghula husk sachets, in particular the elderly

For people who cannot tolerate bulk laxatives or require additional laxatives consider:

Macrogol oral powder, compound
  • Usually 1 sachet once or twice daily in 125ml water
  • To help with cost pressures across the NHS, please prescribe by formulary preferred brand (see 1.6.4 osmotic laxatives)
  • 2-4 tablets at night (short-term use only)

See section 1.6 Laxatives


Doses should be adjusted according to response.

  • Usual dose in diarrhoea-predominant IBS: 4mg initially, followed by 2mg after every loose stool, up to a maximum of 16mg per day.

See section 1.4 Acute diarrhoea

There is evidence suggesting that up to a third of people with a diagnosis of diarrhoea-predominant IBS (IBS-D) have bile acid malabsorption; in patients with significant diarrhoea, despite maximum dose loperamide, GPs may consider the likelihood of bile acid malabsorption diarrhoea. Colestyramine may be used to treat bile acid diarrhoea (unlicensed).

See section 1.9.2 Bile acid sequestrants


Antidepressants are not licensed for use in IBS and should only be used if laxatives, loperamide or antispasmodics have not helped. They may be helpful for the management of functional pain or bloating; Tricyclic antidepressants (TCAs) may also offer an improvement in bowel habit but can induce constipation, therefore their use should be limited to patients with IBS-D.

Amitriptyline (unlicensed indication), should be considered the first choice TCA due to its low acquisition cost

Imipramine (unlicensed indication), less sedating than amitriptyline and should be considered if sedation proves a problem with amitriptyline

Fluoxetine (unlicensed indication), should be considered only if TCAs prove ineffective.

See section 4.3 Antidepressant drugs


  1. Tricyclic antidepressants – treatment should start at a low dose, 5-10mg of amitriptyline to be taken once at night. The dose may be increased to a maximum of 30mg
  2. SSRIs should be considered for patients with IBS only if tricyclic antidepressants have been shown to be ineffective. SSRIs are particularly useful for patients with IBS with constipation. The maximum dose of fluoxetine is 20mg once daily
  3. Prescribers should take into account the possible adverse effects when prescribing tricyclic antidepressants or SSRIs. Patients taking tricyclic antidepressants or SSRIs should be followed-up after 4 weeks and then at 6-12 monthly intervals. Prescribers should be aware that adverse effects may occur sooner than efficacy is observed.

Psychological interventions

If there has been no benefit from dietary and lifestyle advice and pharmacological management after 12 months, consider cognitive behavioural therapy (CBT), which may be available locally or hypnotherapy on a private basis.


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