Implementation of NICE guidance will aid recognition of irritable bowel syndrome and improve care, says Dr Richard Stevens

Seeing a patient with possible irritable bowel syndrome (IBS) is a heart sinking moment for many GPs. They feel uncertain about making the diagnosis, investigation is often haphazard (IBS diagnosis is often, erroneously, called a ‘diagnosis by exclusion’), and response to treatments is poor. The condition can be chronic and this only reinforces the GP’s feelings of frustration and impotence. The recent NICE guideline on the Diagnosis and management of irritable bowel syndrome in primary care aims to change this negative viewpoint.1

Irritable bowel syndrome is one of the most common gastrointestinal disorders and affects between 10% and 20% of the population.1 Only a minority of cases present in primary care but the impact of the condition on a patient’s quality of life can be great and can affect work and relationships. The new guidance seeks to help GPs make a positive diagnosis of the condition and forge a partnership with the patient in managing his or her symptoms.1

Making a positive diagnosis

A positive diagnosis of IBS should only be considered if the patient has abdominal pain or discomfort that is either relieved by defaecation, or associated with altered bowel habit and stool form.1,2,3 This should be accompanied by at least two of the following:

  • altered stool passage (straining, urgency, incomplete evacuation)
  • abdominal bloating (more common in women), distension, tension, or hardness
  • symptoms, which are made worse by eating
  • passage of mucus.

The presence of lethargy, nausea, backache, and bladder symptoms may be used to support the diagnosis.

Traditionally, patients with suspected IBS have had to endure a barrage of often invasive investigations, with many of them ending up in secondary care gastroenterology clinics, and even surgical and gynaecological out-patient departments, where no more can be offered than in primary care. In fact the ongoing relationship with a sympathetic primary care physician can be therapeutic.

Exclusion of other diagnoses

In addition to a history and examination, the following blood tests are recommended to exclude other diagnoses:1

  • full blood count
  • erythrocyte sedimentation rate or plasma viscosity
  • C-reactive protein
  • coeliac disease antibody testing—endomysial antibodies or tissue transglutaminase.

The NICE guideline advises against performing other investigations such as ultrasound, sigmoidoscopy, or colonoscopy in patients who have already satisfied the diagnostic criteria for IBS.


Once a diagnosis of IBS has been made, management is supportive, with advice about diet and lifestyle, and pharmacological treatment. Lifestyle advice should promote physical activity, which will improve general well being and may have benefits for bowel function.

Dietary advice

Patients should be advised of the following:1

  • taking meals at regular intervals
  • drinking adequate amounts, especially water and non-caffeinated drinks such as herbal teas
  • limiting coffee, tea, and alcoholic drinks
  • reducing intake of ‘resistant starch’ often found in processed or re-cooked foods (which is not digested in the small intestine and reaches the colon intact)
  • limiting fresh fruit to three 80 g portions per day
  • in case of diarrhoea, avoiding the artificial sweetener sorbitol, which is present in sugar-free sweets, chewing gums, drinks, and some diabetic and slimming products.

In addition, the patient’s fibre intake should be reviewed and adjusted (usually a reduction) according to symptoms.

If diet is thought to be a major causative factor, and other lifestyle and dietary advice is being followed, the patient with IBS should be referred to a dietitian, who may suggest single food avoidance. An exclusion diet should only be followed under supervision by a dietitian.1

Pharmacological treatment

First-line drug treatment is based on relieving the predominant symptoms. There is a marked placebo effect and good quality drug trials for IBS are sparse.2 However, the NICE guideline recommends single or combination medication alongside dietary and lifestyle advice.

Depending on the symptom profile, it is reasonable to offer an antispasmodic agent if pain is troublesome. When constipation is the predominant feature, laxatives should be considered but the use of lactulose (sugar containing and with potential for increasing bloating) should be avoided. In cases where diarrhoea is the main feature, loperamide is advised as the first choice antimotility agent. Doses of laxative or antimotility drugs can be adjusted for stool consistency.

Tricyclic antidepressants (TCAs) at low doses can be used as second-line pharmacological treatment for their analgesic effect. If TCAs are ineffective, selective serotonin reuptake inhibitors (SSRIs) can be considered. Currently, neither TCAs nor SSRIs are licensed for these purposes in the UK.

Psychological interventions

Some people will have symptoms that do not respond to lifestyle or pharmacological interventions and who develop refractory IBS. If symptoms have not shown an improvement after 12 months of therapy, the guideline recommends consideration for referral for cognitive behavioural therapy, hypnotherapy, and psychological therapy.

Follow up

Alongside all pharmacological and non-pharmacological interventions, the formation of a partnership between GP and patient underpins everything. Follow up after initial interventions and at an annual drug and symptom review are advocated. If red flag symptoms have developed, then the patient should be referred for further investigation. Red flag symptoms include:

  • weight loss—unintentional and unexplained
  • rectal bleeding
  • changed bowel habit lasting more than 6 weeks in patients over 60 years of age—looser and/or more frequent stools.


The guideline from NICE on Diagnosis and management of irritable bowel syndrome in primary care will enable GPs to make a positive diagnosis of IBS with confidence, largely on the basis of history and examination but with some simple blood tests to exclude serious pathology. It sets out the effective, limited treatment options, which should be tailored to the predominant symptoms of each patient. Psychological interventions are recommended for refractory cases and, while these may not always be available currently, this is a tacit recommendation to commissioners.

Click here for CPD questions on this article and the NICE guideline on the diagnosis and management of irritable bowel syndrome


  1. National Institute for Health and Care Excellence. Irritable bowel syndrome in adults: diagnosis and management of irritable bowel syndrome in primary care. Clinical Guideline 61. London: NICE, 2008.
  2. National Collaborating Centre for Nursing and Supportive Care. Diagnosis and management of irritable bowel syndrome in primary care. London: NICE, 2008.
  3. Manning A, Thompson W, Heaton K, Morris A. Towards positive diagnosis of the irritable bowel. Br Med J 1978; 2 (6138): 653–654.G