Understanding irritable bowel syndrome (IBS)

Written by: Dr John Martin
Edited by: Emma McLeod

Irritable Bowel Syndrome (IBS) can be difficult to live with when symptoms are left uncontrolled. If you have been experiencing abdominal pain with diarrhoea, constipation, or both, you could have IBS. Dr John Martin is a consultant gastroenterologist with a vast knowledge of the condition - read on to learn from him about what this condition is, what is needed to make a diagnosis and how treatment is approached between individuals.

A woman lying down with her hands over her stomach in discomfort

What is irritable bowel syndrome?

Irritable bowel syndrome (IBS) is a condition defined by a group of symptoms, rather than by an underlying cause. IBS consists of abdominal pain in association with an alteration in bowel habit. This alteration can be:


IBS is a clinical diagnosis, meaning that it is made on the patient’s history, rather than by tests. There are no tests for IBS because everything in the bowel is normal in patients with this condition. IBS is a “functional” problem, related to how the bowel works or to increased sensitivity within the bowel, rather than abnormalities such as inflammation, which occurs in conditions like inflammatory bowel disease (IBD) – a condition commonly confused with IBS.


What causes it?

We do not know the cause of IBS, however, we know that the development of symptoms can be associated with triggers such as stress and anxiety.


Sometimes, certain foods can trigger symptoms, but this is not the result of a true food allergy and is best described as an intolerance. Identifying foods that trigger IBS symptoms is best done by keeping a food diary, but there is no way to test for them clinically.


Symptoms of IBS can persist for a long time and lead to patient anxiety from them worrying that there is a serious underlying cause. Reassurance that this is not the case is often extremely helpful and, in some cases, may result in an improvement of symptoms. It is important to stress that in the absence of symptoms that suggest an alternative diagnosis multiple investigations are unhelpful, and may even be detrimental by increasing anxiety that no cause can be found to explain the symptoms.


What are the symptoms?

The key symptoms of IBS are abdominal pain and change in bowel habit i.e. diarrhoea, constipation or alternating between both. The symptoms need to have been present for at least three months to make the diagnosis, although some patients will have had problems for much longer before seeking help.


Patients with IBS may also complain of many other symptoms that are not directly attributable to the gut. It is important to mention these to your specialist and they may influence the choice of treatment offered.

Examples of such symptoms include:


Do IBS symptoms overlap with other conditions?

IBS is completely benign and does not lead to other conditions. Generally, it can be diagnosed without any investigations but, sometimes, if there are atypical features, then tests will be needed to exclude another diagnosis such as coeliac disease, inflammatory bowel disease like Crohn’s Disease, or in very rare cases, malignancy.


Examples of symptoms that are not suggestive of a diagnosis of IBS and would require further investigation include:


How is it treated?

The underlying cause of IBS is not fully understood, so it is not possible to give medications to treat this. Treatment is therefore tailored to manage symptoms and in IBS this is sufficient, as there are no health consequences of the condition.


There are a variety of approaches used in the management of IBS, including:

  • Reassurance: Often an explanation of the condition and the symptoms is sufficient to reassure patients that there is no serious health condition, and may result in improvement.
  • Laxatives/Fibre supplements/Anti-diarrhoea medications: These agents can be used to treat the bowel disturbance in IBS. They may only be required for a short period, but are safe to take long-term in patients that require it.
  • Anti-spasmodic medications: These are often used to relieve the cramps that are very common in patients with IBS.
  • Dietary approaches: Trying one or more dietary approaches helps to identify food intolerances that trigger IBS symptoms. The low FODMAP diet is the most commonly used diet to treat symptoms of IBS and can be particularly helpful to treat bloating.
  • Anti-depressants: In more severe cases, anti-depressants are used to modulate nerves and decrease gut sensitivity.


Patients may also benefit from other treatments such as probiotics, aloe verabiofeedback therapy or clinical hypnosis.


Can it be cured?

The aim of treatment in IBS is relief of symptoms and if this is achieved, the condition has been “cured”. Some patients need to try various treatments before they get their symptoms under control, but about 4 in 10 patients will improve.

IBS, however, is a chronic condition and some patients (about a third to a half) will continue to experience symptoms despite treatments, and these may be triggered or worsened by stressful life events.


Don’t hesitate to visit Dr Martin’s Top Doctors profile to learn how he can help you and to get in touch.

By Dr John Martin

Dr John Martin graduated from Cambridge University and King’s College Hospital, London in 1990 and completed his gastroenterology training within North West London.  He is a highly-experienced gastroenterologist and endoscopist based in London and holds an NHS Consultant post at Imperial College (ICL).  He is an expert in colorectal cancer screening, therapeutic and diagnostic colonoscopy and has 25 years experience of managing all aspects of gastroenterology including abdominal pain or discomfort, reflux disease, diarrhoea and constipation, rectal bleeding, Irritable Bowel Syndrome, Crohn’s Disease and Ulcerative Colitis.

Dr Martin teaches colonoscopy both within the  NHS Trust and also at national screening centres. He is a bowel cancer screening accredited colonoscopist and an examiner for BCSP colonoscopy accreditation.

Dr Martin is Director of the West London Bowel Cancer Screening Centre, he is the national advisor to Public Health England on endoscopy within the Bowel Cancer screening service and chairs the national advisory committee on quality and safety of endoscopy within screening. He forms an integral part of numerous other professional bodies and has been widely published in peer-reviewed journals.

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