What is Irritable Bowel Syndrome?

Irritable bowel syndrome (IBS) is a term for a condition characterized by abdominal pain, bloating and a change in bowel habit. It is a functional bowel disease in that there is no apparent structural problem with the bowel but for a variety of reasons, the bowel produces symptoms.


Some people have mostly a loose stool, some mostly constipation and other alternate between the two.

In the younger age group the pain is better after a bowel action, there may be rapidly alternating diarrhoea and constipation and to make the diagnosis there should be two of the following symptoms:-

  • Bloating
  • The sensation of incomplete evacuation of the bowel
  • Symptoms made worse by eating, often specific foods
  • Passage of mucus
  • Tiredness

In this younger group, if some baseline blood tests are normal (check for anaemia, inflammation and coeliac disease) then a positive diagnosis can be made without further investigations.

The problem in the older age groups is that these symptoms overlap with many other conditions, some serious, so that it becomes essential to exclude these conditions, usually by colonoscopy.


If you have bowel symptoms, once you have explained these to your surgeon and IBS is suspected, you will need a physical examination in the clinic, some blood tests might be required and then some patients will need a colonoscopy. Sometimes a stool test called faecal calprotectin can be useful to exclude inflammatory bowel disease.


Once the colon has been seen to be normal to the eye, then treatment of symptoms can start. Interestingly after the laxatives given for a colonoscopy many patients report an improvement in symptoms when they come back to the clinic for review, particularly if the main problem was a loose stool. It’s almost like “rebooting” the colon. It is speculated this effect is due to prior imbalances in bacteria in the colon.

General attention to a healthy life-style is important to some, for example taking adequate exercise, making the most of leisure time to relax. It’s not uncommon for symptoms to disappear on holiday.

Dietary manipulation

There are many changes to diet which might help and often a specialist dietician can be very helpful in managing this. In general some other the following changes can be effective:-

  • Avoid caffeine
  • Reduce fibre in the diet (cereals, wholemeal bread, brown rice)
  • Reduce fibre that is “insoluble” eg bran as this reaches the colon and so can be digested by bacteria leading to bloating.
  • If fibre is needed then “soluble fibre” such as oats and cracked linseed is better
  • Avoid sorbitol, an artificial sweetener in some sweets and drinks

There are some patients who become intolerant of certain subgroups of food. Wheat, yeasts and dairy products are commonly a problem so excluding these can help. Its important to do this under guidance of a clinician or dietician as for example dairy products are an important source of calcium which will need replacing. There are many other dietary manipulations that can be offered such as an exclusion diet, a low FODMAP diet and all of these can be discussed with your surgeon in the clinic.

Drug therapy

Sometimes drugs can help symptoms and these include a low dose of amitriptyline at night, SSRIs (seratonin reuptake inhibitors), loperamide to reduce diarrhoea. There are some new drugs available that draw fluid into the colon and help patients where constipation is the predominant symptom, ie linaclotide and lubiprostone. If any other of these is suitable then they will be discussed with you.