Irritable bowel syndrome (IBS)

What is irritable bowel syndrome (IBS) ?

Irritable bowel syndrome is a very common condition, that may affect up to 1 in 5 people living in Australia. It describes a wide range of symptoms that vary from one person to another. IBS is a real entity and can cause significant interference with people’s work and relationships.

The most common symptoms of irritable bowel syndrome are:

  • Diarrhoea or constipation, or both
  • Lower abdominal cramping, often related to opening the bowels
  • Excessive wind and / or abdominal bloating or distension.
  • Feeling the need to open the bowels, even after having just been to the toilet
  • A feeling of urgency (needing to rush to the toilet)
  • Feeling that your symptoms are worse after eating

Many different theories abound regarding what might cause or contribute to irritable bowel syndrome (IBS) including stress, anxiety, foods that are eaten, or alcohol. In addition there are hundreds of therapies being offered from every field including probiotics, vitamins, naturopathy, homeopathy and acupuncture. This makes management of irritable bowel syndrome very confusing for those suffering these symptoms.

Many different factors have been suggested as contributing to IBS. This includes visceral hypersensitivity (‘oversensitive nerves in the gut’), and also increased intestinal permeability (‘leaky gut’) which may cause diarrhoea. The concept of the ‘brain-gut axis’ is well recognised, and patients with IBS may have a background of depression, anxiety or stressful factors in their life which may contribute.

The approach to IBS can be divided into diagnosis of IBS and management of IBS. From the point of view of diagnosis, IBS can often be diagnosed by the doctor taking a history and performing an examination if the story is typical. A classical story is alternating diarrhoea and constipation, associated with bloating and lower abdominal cramping. The diarrhoea tends to be low volume and does not occur at night. Alternatively there may be ‘diarrhoea predominant’ IBS or ‘constipation predominant’ IBS.

Your doctor may want to exclude other causes of these symptoms, especially if the story is not ‘classical’. Your gastroenterologist may want to rule out other conditions such as inflammatory bowel disease, microscopic colitis, pancreatic insufficiency or small intestinal bacterial overgrowth. In some patients, bowel cancer can mimic the symptoms of irritable bowel syndrome and warrants exclusion. One investigation involves a ‘colonoscopy’ which is a thin tube with a camera on the end which examines the entire large bowel under a light anaesthetic. Ruling out coeliac disease is important, and the ‘gold standard’ is gastroscopy with duodenal biopsies to achieve this.

The management of patients with IBS encompasses a number of different areas and can be used in a stepwise approach. This includes dietary intervention, antispasmodics, medications to affect the nerves in the gut and other therapies. In terms of dietary interventions, the low FODMAP diet has been shown to improve symptoms in many patients with IBS, however this is not a panacea for all patients. Those with refractory symptoms may be candidates for second-line therapies.

In terms of general advice, meal times should be regularised, and soft drinks and chewing gum should be reduced or avoided. Antispasmodics such as peppermint oil, buscopan or mebeverine can be used if abdominal cramping is a problem. In terms of medications, the use of medications originally designed as antidepressants such as amitriptylline or SSRIs can be useful in some patients. If anxiety or depression is an issue, this should be discussed with your clinician. In some patients, talking therapy such as cognitive behavioural therapy with a psychologist may be of benefit.

Note that this document is a guideline and individual treatment should be discussed with your clinician.