Summary
Read the full fact sheet- Irritable bowel syndrome is characterised by abdominal discomfort, bloating and a change in bowel habits (constipation or diarrhoea).
- There is no single cause for this condition, but environmental factors – such as changes of routine, emotional stress, infection, toileting behaviours and diet – can trigger symptoms.
- Treatment options include careful changes to diet, laxatives, anti-diarrhoea medications, antispasmodics, psychological therapies and physical and behavioural therapies.
On this page
Around one in five Australians experiences the unpleasant symptoms of irritable bowel syndrome (IBS) at some time. These include abdominal pain, bloating, mucus in the stools, and either diarrhoea, constipation or a mixture of both.
Irritable bowel syndrome is a condition commonly referred to as a functional gastrointestinal disorder. A new description of this condition is that IBS is a disorder of brain gut interaction, highlighting the importance of the brain and its relationship with gut function. More women than men are prone to IBS, and symptoms tend to first occur in early adulthood.
There is no one cause for Irritable Bowel Syndrome. Each individual will experience symptoms of IBS due to their own unique factors. These factors include changes of routine, emotional stress, infection, psychological distress, inappropriate toileting dynamics and diet. Other important factors include neurotransmitters, gut microbiota and intestinal motility.
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
- Diarrhoea and constipation (which may occur together)
- A sensation that the bowels are not fully emptied after passing a motion
- Abdominal bloating and distension
None of these symptoms are exclusive to IBS. It is uncommon for IBS to produce these symptoms, for the first time, after the age of 40.
Main IBS categories
Irritable bowel syndrome can be subdivided into three major categories:
- Constipation-predominant – the person tends to alternate constipation with normal stools.
- Diarrhoea-predominant – the person tends to experience loose stools which may occur frequently. The need to go to the toilet can be urgent and cannot be delayed. Incontinence may be a problem.
- Alternating constipation and diarrhoea.
Causes of IBS
The underlying cause of irritable bowel syndrome is likely to be explained by many different factors, unique to each individual. Certain factors have been found to ‘trigger’ attacks in susceptible individuals. These include:
- Infection – an episode of gastroenteritis will often result in persistent bowel symptoms, long after the offending bacteria or virus has been eliminated.
- Food intolerance – Foods which are poorly absorbed (such as the the carbohydrates which are referred to as “FODMAPS” – fermentable oligosaccharides, disaccharides, monosaccharides and polyols) are the most common dietary trigger for IBS. These carbohydrate “sugars” include fructose, lactose and sorbitol.
- Emotional stress – strong emotions, such as anxiety or stress, can affect the nerves of the bowel in susceptible people.
- Inappropriate regulation of signalling between the brain and the gut. Sometimes this is referred to as “visceral hypersensitivity” (sensitive gut)
- Medication – certain types (such as antibiotics, antacids and painkillers) can lead to constipation or diarrhoea.
Diagnosis of IBS
If you suspect you have irritable bowel syndrome, it is important to seek medical advice to make sure your symptoms aren’t caused by any other illness, such as diverticulitis, inflammatory bowel disease. Coeliac disease (an immune intolerance to gluten, present in wheat and other grains) may produce symptoms commonly seen in IBS. Lactose intolerance may produce bloating, cramps and diarrhoea.
Most people can be diagnosed with IBS without the need for invasive testing.
Diagnosis methods include:
- full medical check-up
- blood tests, including blood tests for coeliac disease
- stool tests to exclude inflammatory bowel disease
- investigation of the stomach or bowel under sedation (Gastroscopy /colonoscopy).
Treatment for IBS
IBS can be successfully managed with treatments which are tailored to the individual. Clinicians will often recommend identifying and avoiding triggers. Treatment options may include:
- An increase in dietary fibre, together with clear fluids
- Moderating common gas-producing foods, or undertaking a diet with a trained dietician, such as a low “FODMAP” diet – Fructose, Lactose, Sorbitol.
- Antidiarrhoea medication, such as loperamide – for those with diarrhoea-predominant IBS
- Laxatives for constipation
- Antispasmodic drugs, which may ease cramping – examples include mebeverine, hyoscine and peppermint oil capsules
- Tricyclic antidepressants – These are effective in treating pain, bloating and bowel frequency in IBS. Use of these medications does not mean that IBS is caused by depression or anxiety.
- Psychological therapies, including cognitive behavioural therapy and gut directed hypnotherapy. These treatments involve a trained psychologist or can be delivered through online platforms.
- Behavioural and pelvic floor therapies. Often symptoms of IBS can be caused by inability to effectively defecate, trained pelvic floor physiotherapists can treat this effectively.
Specific treatments for IBS are not approved for use
A small number of medications have been developed to treat IBS and have been shown to be effective in selected groups in clinical trials. These work on the interaction between serotonin and nerve cells of the colon. They include alosetron, cilansetron and tegaserod.
Safety concerns with these three medications has led to their withdrawal from the market, or restricted use only, and none are presently licensed in Australia. Microbiota altering therapies such as faecal microbiota transplantation are considered experimental and preliminary clinical studies have not shown this therapy to be clearly effective.
Find an experienced health professional
People with IBS can become frustrated and feel their symptoms are not treated seriously. These frustrations, along with sometimes inappropriate therapy, can often make the symptoms worse. Finding a therapist with experience in the successful treatment of IBS is important. Being treated by a multidisciplinary team is optimal.
Where to get help
- Moleski S 2013, ‘Irritable bowel syndrome (IBS)’, The Merck Manual of Diagnosis and Therapy, Merck & Co.
- Tack J, Fried M, Houghton LA et al. 2006, ‘Systematic review: the efficacy of treatments for irritable bowel syndrome – a European perspective’, Alimentary Pharmacology and Therapeutics, vol. 24, no. 2, pp. 183–205.
- Evans BW, Clark WK, Moore DJ, Whorwell PJ 2008, ‘Tegaserod for the treatment of irritable bowel syndrome’, The Cochrane Database of Systematic Reviews, vol. 1, CD003960.
- Heading R, Bardhan K, Hollerbach S et al. 2006, ‘Systematic review: the safety and tolerability of pharmacological agents for treatment of irritable bowel syndrome – a European perspective’, Alimentary Pharmacology and Therapeutics, vol. 24, no. 2, pp. 207-236.
- Low FODMAP diet for irritable bowel syndrome, Medicine, Nursing and Health Sciences, Monash University.
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