1. Dr.Schär Institute
  2. Dr. Schär Institute
  3. Symptoms

Symptoms of Irritable bowel syndrome (IBS) are often non-specific, including diarrhoea, abdominal pain, bloating, postprandial fullness and constipation.

The Rome III criteria are the gold standard for IBS diagnosis. The Rome criteria is a system developed to classify functional gastrointestinal disorders, disorders of the digestive system in which symptoms cannot be explained by the presence of structural or tissue abnormality, based on clinical symptoms.

Rome III Irritable Bowel Syndrome Diagnostic Criterion

Recurrent abdominal pain or discomfort at least 3 days/month in the last 3 months associated with two or more of the following [1,2]:

  1. Improvement with defecation
  2. Onset associated with a change in frequency of stool
  3. Onset associated with a change in form (appearance) of stool 

UK NICE IBS guidelines

The National Institute of Clinical Excellence produced guidance on the diagnosis and management of IBS in 2008, these were updated in 2015 and state that IBS 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. This guidance provides further clarification by confirming that symptoms of IBS may include disordered defaecation (constipation or diarrhoea or both) and abdominal distension, usually referred to as bloating. Other features such as lethargy, nausea, backache and bladder symptoms are common in people with IBS, and may be used to support the diagnosis.  [3,4]

Ruling out other conditions

  • Coeliac disease, bile-salt malabsorption, bowel cancer, gastrointestinal food allergy and inflammatory bowel disease can all exhibit similar gut symptoms. Hence, it is vital that a full case history is taken. If there is any suspicion or presence of red flags then the patient must be referred immediately for further tests and investigations [3,5].

Red Flags indicating requirement for onward referral/ investigation

  • The presence of certain ‘red flag’ symptoms in a patient presenting with suspected IBS may indicate an alternative diagnosis and therefore prompt further investigation by the clinician [3]. Such symptoms are outlined below:
  • Unintentional and unexplained weight loss
  • Rectal bleeding
  • Family history of bowel or ovarian cancer
  • A change in bowel habit to looser and/or more frequent stools persisting for more than 6 weeks in a person aged over 60 years
  • Unexplained anaemia
  • Abdominal masses
  • Rectal masses
  • Inflammatory markers for inflammatory bowel disease


  1. Drossman DA. The functional gastrointestinal disorders and the Rome III process. Gastroenterology. 2006;130(5):1377-90.
  2. Longstreth GF, Thompson WG, Chey WD, Houghton LA, Mearin F, Spiller RC. Functional bowel disorders. Gastroenterology. 2006;130(5):1480-91.
  3. National Institute for Health and Clinical Excellence. Irritable bowel syndrome in adults: Diagnosis and management of irritable bowel syndrome in primary care. London 2008.
  4. National Institute for Health and Care Excellence. Irritable bowel syndrome in adults: diagnosis and management of irritable bowel syndrome in primary care. London: NICE; 2015.
  5. Holgate ST CM, Broide DH, Martinez FD,. Allergy. 4th Edition ed: Elsevier Saunders; 2012.