An Introduction to IBS

What is IBS?

IBS stands for irritable bowel syndrome.  It is a chronic condition that affects the digestive system, requiring long term management, as currently there is no known cure. It is estimated that IBS affects around 11% of the global population (1) and approximately 17% of the UK population (2). 

Symptoms vary from person to person but a common theme is frequent abdominal discomfort and bowel symptoms not explained by another disease, with either predominantly diarrhoea (IBS-D), constipation (IBS-C) or both (IBS-M) (1). 

IBS Symptoms

Generally the main symptoms to look out for include (3): 

– abdominal pain 

– constipation 

– diarrhoea 

– bloating 

Other symptoms include (3) :

– flatulence 

– passing mucus from your bottom 

– tiredness and lack of energy – particularly after an IBS attack 

– feeling sick 

– backache 

– problems peeing – feeling the need to pee all the time, feeling like you cant empty your bladder 

– incontinence

There is evidence to support that women may experience worsening or a change in symptoms during their period (4).  So when you are approaching your time of the month don’t be alarmed by any changes from your normal. However, if things change drastically or your symptoms become abnormal and to difficult to manage consult your doctor as it may be more than IBS. 

Symptoms not related to IBS and that could be a sign of something more serious include: 

– sudden weightless for no reason 

– bleeding from your bottom or bloody diarrhoea 

– hard lump or swelling in tummy/abdomen 

– shortness of breath, noticeable heartbeats and pale skin 

These are all very serious and require you to make an urgent appointment with your doctor. 

Classifying IBS

For clinical purposes IBS is categorised based on your most predominant bowel symptoms. Approximately one third of patients have IBS-C, a third have IBS- D and the rest have IBS-M. While it is useful to categorise for clinical purposes it is not uncommon for IBS sufferers to switch sides over time. It is estimated that more than 75% of IBS patients will change to either of the two subtypes at least once over a year (5). 

If you find you fluctuate between the two don’t be alarmed. While this is annoying, as it can make it more difficult to manage symptoms, this is completely normal when it comes to IBS.  

How is IBS Diagnosed?

To date there is no biochemical, radiological or histopathological tests for IBS and diagnosis is based on symptom assessment.  

Symptom assessment is done using the Rome III criteria°. To be diagnosed you should meet the following requirements (6):  

  • Recurrent abdominal pain or discomfort °° at least 3 days/month in last 3 months associated with or more of the below criteria
  • Improvement with defecation – pain or discomfort gets better after bowel movement at least sometimes
  • Onset associated with a change in frequency of stool – onset of pain or discomfort associated with stools at least sometimes, or onset of pain or discomfort associated with fewer stools at least sometimes
  • Onset associated with a change in form (appearance) of stool – onset of pain or discomfort associated with looser stools at least sometimes, or onset of pain or discomfort associated with harder stools at least sometimes

° Criteria fulfilled for the past 3 months with symptom onset at least 6 months before diagnosis 

°° ‘discomfort’ means an uncomfortable sensation not described as pain 

The National Institute for Health and Clinical Excellence (NICE), recommend to healthcare professionals to look for the following presenting in patients for at least 6 months(7):

 – Abdominal pain/ discomfort

– Bloating 

– Changes in bowel habit 

I have outlined above a way of diagnosing IBS and you may have experienced all these symptoms yourself and be pretty confident you have IBS, however, it is important to not self diagnose and make sure you get checked out by your GP to rule out any other series conditions. 

Causes of IBS

For some, symptoms start seemingly out of the blue after years of having a healthy functioning digestive system. For others, they have struggles with chronic digestive health issues for what can feel like their whole lives. The direct cause of IBS is unknown, but we do know that certain illnesses and stressful incidences in your life can have a direct impact in developing IBS. 

There are multiple factors that can play a role in developing IBS. There is evidence to show that the following may play a key role in developing the disease (8):

  1. Heritability and genetics 
  2. Environment 
  3. Diet 
  4. Intestinal microbiota 
  5. Low grade inflammation 
  6. Disturbance of your gut-brain axis 

So there you have it, a general overview of IBS. If you are concerned you might have IBS, always speak to your doctor to get a proper diagnosis and rule out any other potential conditions.

If you want to learn more about IBS, take a look at the following articles:


  1. Canavan, C., West, J. and Card, T., 2014. The epidemiology of irritable bowel syndrome. Clinical epidemiology, 6, p.71.
  2. Khanbhai, A. and Sura, D.S., 2013. Irritable bowel syndrome for primary care physicians. Br J Med Pract, 6(1), p.a608.
  3. NHS “Symptoms of IBS” –
  4. Houghton, L.A., Lea, R., Jackson, N. and Whorwell, P.J., 2002. The menstrual cycle affects rectal sensitivity in patients with irritable bowel syndrome but not healthy volunteers. Gut, 50(4), pp.471-474.
  5. Drossman, D.A., Morris, C.B., Hu, Y., Toner, B.B., Diamant, N., Leserman, J., Shetzline, M., Dalton, C. and Bangdiwala, S.I., 2005. A prospective assessment of bowel habit in irritable bowel syndrome in women: defining an alternator. Gastroenterology, 128(3), pp.580-589
  6. Spiller, R., Aziz, Q., Creed, F., Emmanuel, A., Houghton, L., Hungin, P., Jones, R., Kumar, D., Rubin, G., Trudgill, N. and Whorwell, P., 2007. Guidelines on the irritable bowel syndrome: mechanisms and practical management. Gut, 56(12), pp.1770-1798.
  7. Irritable bowel syndrome in Adults. Diagnosis and management of irritable bowel syndrome in primary care. National Institute for Health and Clinical Excellence (NICE). February 2008
  8. El-Salhy M. Irritable bowel syndrome: Diagnosis and pathogenesis. World Journal of Gastroenterology 2012 October 7; 18(37): 5151-5163

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