• Incidence: 2000.00 cases per 100,000 person-years
  • Peak incidence: 30-40 years
  • Sex ratio: more common in males 2:1
Condition Relative
Irritable bowel syndrome1
Coeliac disease0.05
Microscopic colitis0.01
<1 1-5 6+ 16+ 30+ 40+ 50+ 60+ 70+ 80+

Clinical features

The diagnosis of IBS should be considered if the patient has had the following for at least 6 months:

A positive diagnosis of IBS should be made if the patient has abdominal pain relieved by defecation or associated with altered bowel frequency stool form, in addition to 2 of the following 4 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

Features such as lethargy, nausea, backache and bladder symptoms may also support the diagnosis

Red flag features should be enquired about:
  • rectal bleeding
  • unexplained/unintentional weight loss
  • family history of bowel or ovarian cancer
  • onset after 60 years of age


Suggested primary care investigations are:
  • full blood count
  • coeliac disease screen (tissue transglutaminase antibodies)


The management of irritable bowel syndrome (IBS) is often difficult and varies considerably between patients. NICE updated it's guidelines in 2015.

First-line pharmacological treatment - according to predominant symptom

For patients with constipation who are not responding to conventional laxatives linaclotide may be considered, if:
  • optimal or maximum tolerated doses of previous laxatives from different classes have not helped and
  • they have had constipation for at least 12 months

Second-line pharmacological treatment
  • low-dose tricyclic antidepressants (e.g. amitriptyline 5-10 mg) are used in preference to selective serotonin reuptake inhibitors

Other management options
  • psychological interventions - if symptoms do not respond to pharmacological treatments after 12 months and who develop a continuing symptom profile (refractory IBS), consider referring for cognitive behavioural therapy, hypnotherapy or psychological therapy
  • complementary and alternative medicines: 'do not encourage use of acupuncture or reflexology for the treatment of IBS'

General dietary advice
  • 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 such as herbal teas
  • restrict tea and coffee to 3 cups per day
  • reduce intake of alcohol and fizzy drinks
  • consider limiting intake of high-fibre food (for example, wholemeal or high-fibre flour and breads, cereals high in bran, and whole grains such as brown rice)
  • reduce intake of 'resistant starch' often found in processed foods
  • limit fresh fruit to 3 portions per day
  • for diarrhoea, avoid sorbitol
  • for wind and bloating consider increasing intake of oats (for example, oat-based breakfast cereal or porridge) and linseeds (up to one tablespoon per day).