Irritable Bowel Syndrome

Medibank Health Directory

What is irritable bowel syndrome?

Irritable bowel syndrome (IBS) is a common digestive disorder with symptoms including abdominal pain, bloating, diarrhea and constipation.

While the underlying cause is unknown, the most common trigger is food intolerance.

Most often, treatment consists of identifying trigger foods and managing the diet to relieve symptoms.

Irritable bowel syndrome (IBS) is a disorder of the gastrointestinal tract that causes symptoms such as abdominal pain, bloating, mucus in the stools, and alternating diarrhoea and constipation.

The cause of IBS is unknown but environmental factors such as diet, emotional stress, changes of routine and infection can trigger attacks. IBS can cause a great deal of discomfort and distress but it does not result in permanent harm to the bowel, nor does it increase the risk of developing bowel cancer.

Women are two to three times more likely to be diagnosed than men, and it is unusual for IBS to appear for the first time after the age of 40.

Causes of irritable bowel syndrome

It is believed that people with IBS have overly sensitive bowels, likely due to higher-than-usual levels of the bacterial flora normally found in the bowels. While the underlying cause is still unknown, certain factors have been found to trigger attacks in people who are susceptible.

Food intolerance is the most common dietary trigger for IBS. This occurs when absorption of the sugar lactose (found in dairy and many processed foods) is impaired (lactose intolerance). Other sugars believed to trigger IBS are fructose and sorbitol.

Certain foods – fatty or spicy foods, alcohol, grain-based foods – may trigger symptoms. However, many experts are sceptical about the role of general diet, once specific food intolerances have been eliminated. Please note – IBS and coeliac disease are not related.

An episode of gastroenteritis can result in persistent bowel symptoms, long after the offending bacteria or virus has been eliminated. Up to 25% of IBS cases may be triggered by this kind of infection.

While emotional stress or anxiety or stress may worsen symptoms, research has shown that emotional factors do not cause IBS.

Symptoms of irritable bowel syndrome

There is no rigid reference for 'normal' bowel behaviour – bowel movements may range from as many as three stools a day to as few as three a week. A healthy bowel movement is one that is formed but not hard, contains no blood and is passed without cramps or pain.

IBS cases fall into three major categories:

  • Constipation-predominant - constipation alternating with normal stools, with abdominal cramps or aching after eating
  • Diarrhoea-predominant - diarrhoea occurring first thing in the morning or after eating, with an urgent need to go to the toilet
  • Alternating constipation and diarrhoea

Common signs of IBS include:

  • Abdominal pain, cramping or nausea
  • Diarrhoea and/or constipation
  • Bloating
  • A sensation of incomplete evacuation after defecation
  • Mucus in the stools

Treatment of irritable bowel syndrome

If you suspect you have IBS, it is important to seek medical advice to make sure your symptoms aren’t caused by other illnesses, such as inflammatory bowel disease or bowel cancer.

There is currently no cure for IBS, but for many people, eating a healthy diet and avoiding trigger foods is enough to relieve the symptoms. Treatments may include:

  • Increasing dietary fibre (for constipation-predominant IBS)
  • Antidiarrhoeals (for diarrhoea-predominant IBS)
  • Reducing or eliminating dairy foods, if lactose intolerance is a trigger
  • Pain-relieving medications
  • Medications to treat constipation
  • Antispasmodic drugs to ease cramping
  • Establishing eating routines and avoiding sudden changes of routine
  • Regular physical activity to help relieve factors such as stress and assist bowel function

Further information and sources


This article is of a general nature only. You should always seek medical advice if you think you may have the symptoms of irritable bowel syndrome.