Irritable bowel syndrome (IBS) is a chronic, relapsing and often life‑long disorder. It is characterised by the presence of abdominal pain or discomfort, which may be associated with defaecation and/or accompanied by a change in bowel habit. Symptoms may include disordered defaecation (constipation or diarrhoea or both) and abdominal distension, usually referred to as bloating. Symptoms sometimes overlap with other gastrointestinal disorders such as non‑ulcer dyspepsia or coeliac disease. People with IBS present to primary care with a wide range of symptoms, some of which they may be reluctant to disclose without sensitive questioning.

People with IBS present with varying symptom profiles, most commonly 'diarrhoea predominant', 'constipation predominant' or alternating symptom profiles. IBS most often affects people between the ages of 20 and 30 years and is twice as common in women as in men. Prevalence in the general population is estimated to be between 10% and 20%. Recent trends indicate that there is also a significant prevalence of IBS in older people. IBS diagnosis should be a consideration when an older person presents with unexplained abdominal symptoms.

Key aspects of this guideline include establishing a diagnosis; referral into secondary care only after identification of 'red flags' (symptoms and/or features that may be caused by another condition that needs investigation); providing lifestyle advice; drug and psychological interventions; and referral and follow‑up. The guideline refers to NICE's guideline on suspected cancer: recognition and referral in relation to appropriate referral to secondary care.

The main aims of this guideline are to:

  • provide positive diagnostic criteria for people presenting with symptoms suggestive of IBS

  • provide guidance on clinical and cost‑effective management of IBS in primary care

  • determine clinical indications for referral to IBS services, taking into account cost effectiveness.

Recommendations about medicines

The guideline will assume that prescribers will use a medicine's summary of product characteristics to inform decisions made with individual patients.

This guideline recommends some medicines for indications for which they do not have a UK marketing authorisation at the date of publication, if there is good evidence to support that use. The prescriber should follow relevant professional guidance, taking full responsibility for the decision. The patient (or those with authority to give consent on their behalf) should provide informed consent, which should be documented. See the General Medical Council's Good practice in prescribing and managing medicines and devices for further information. Use of medicines outside their licensed indications ('off‑label use') are noted in the recommendations.