Irritable bowel syndrome

Around one in five Australians experiences the unpleasant symptoms of irritable bowel syndrome (IBS) at some time. These include abdominal pain, mucus in the stools, and alternating diarrhoea and constipation. Other terms for irritable bowel syndrome include ‘spastic colon’ and ‘irritable colon’. It seems that people with IBS have sensitive bowels that are easily ‘upset’. More women than men are prone to IBS, and symptoms tend to first occur in early adulthood.

The cause is unknown, but environmental factors such as changes of routine, emotional stress, infection and diet can trigger an attack. Research has shown that the neurotransmitter serotonin may be important in the symptoms of IBS, by altering the function of nerve cells in the bowel and causing changes in pain sensation and bowel function.

Irritable bowel syndrome doesn’t cause lasting damage and doesn’t contribute to the development of serious bowel conditions, such as cancer or colitis.

Symptoms of IBS
Some of the more common signs of irritable bowel syndrome include:

• Abdominal pain or cramping that is often relieved by passing wind or faeces
• Alternating diarrhoea and constipation
• A sensation that the bowels are not fully emptied after passing a motion
• Abdominal bloating
• Mucus present in the stools
• Nausea.

• Constipation-predominant – the person tends to alternate constipation with normal stools. Symptoms of abdominal cramping or aching are commonly triggered by eating.
• Diarrhoea-predominant – the person tends to experience diarrhoea first thing in the morning or after eating. The need to go to the toilet is typically urgent and cannot be delayed. Incontinence may be a problem.
• Alternating constipation and diarrhoea.

• Infection – an episode of gastroenteritis will often result in persistent bowel symptoms, long after the offending bacteria or virus has been eliminated. The cause of this is unknown, but may involve changes to nerve function in the bowel or changes in the normal bacterial population of the bowel. Up to 25 pre cent of IBS may be due to this problem.
• Food intolerance – impaired absorption of the sugar lactose (found in dairy and many processed foods) is the most common dietary trigger for IBS. Other sugars believed to trigger IBS are fructose (present in many syrups) and sorbitol.
• General diet – low fibre diets can exacerbate the constipation of constipation-predominant IBS. Some people find spicy or sugary foods cause problems. However, many experts are skeptical about the role of general diet, once specific food intolerances have been eliminated.
• Emotional stress – strong emotions, such as anxiety or stress, can affect the nerves of the bowel in susceptible people.
• Medications – certain drugs (such as antibiotics, antacids and painkillers) can lead to constipation or diarrhoea.

• Full medical check-up
• Blood tests, including blood tests for coeliac disease
• Stool tests
• Investigation of the bowel lining by inserting a small tube (sigmoidoscopy)
• Investigation of the bowel under sedation (colonoscopy) or barium enema, if necessary.

• A modest increase in dietary fibre, together with plenty of clear fluids
• Reducing or eliminating common gas-producing foods, such as beans and cabbage
• Reducing or eliminating dairy foods, if lactose intolerance is a trigger
• Antidiarrhoeals, such as imodium or lomotil – these can be an essential part of management in those with diarrhoea-predominant IBS
• Pain-relieving medications – opiates such as codeine can provide effective pain relief. One of their most common side effects, constipation, may also relieve the diarrhoea of diarrhoea-predominant IBS
• Drugs or treatments to treat constipation
• Antispasmodic drugs, which may ease cramping – examples include mebeverine, belladonna, hyoscine and peppermint oil capsules
• Tricyclic antidepressants – these can be effective in treating the pain of IBS, but are best prescribed for a trial period with monitoring of symptoms. Use of these medications does not mean that IBS is caused by depression
• Stress management, if stress seems to be triggering the attacks
• Establishing eating routines and avoiding sudden changes of routine.

• Your doctor
• Irritable Bowel Information and Support Association website
• An accredited practising dietitian, contact the Dietitians Association of Australia

• Irritable bowel syndrome is characterised by abdominal pain, bloating and alternating constipation and diarrhoea.
• The cause is unknown, but environmental factors – such as changes of routine, emotional stress, infection and diet – can trigger an attack.
• Treatment options include careful changes to diet over a period of time, laxatives or antidiarrhoeals, and antispasmodics.

This page has been produced in consultation with, and approved by:


(Logo links to further information)