What is IBS

IBS is a very common gastrointestinal disorder that affects 1 in 7 people. Once known as ‘spastic colon’, abdominal pain and abnormal bowel habits (constipation, diarrhoea or a mixture of both) are key features of IBS. Other symptoms may also be present including:

  • bloating (the sensation of an inflated balloon in the abdomen)
  • distension ( a visible increase in abdominal girth)
  • excessive gas (farts / wind)
  • urgency to defacate (poo)

What causes IBS?

We still do not know what causes IBS, although a number of factors are thought to play a role. These includes:

Disturbances in the speed at which contents more through the gut

This means that contents move through the gut at an unusually quickly or unusually slowly. Around 1 in 3 people with IBS are thought to have this problem. If movement through the gut is unusually fast, this may result in diarrhoea. Whereas, if movement through the gut is unusually slow this may result in constipation.

Overly sensitive gut wall

People with IBS may have a highly sensitive gut wall. This means they are more sensitive to normal movements of the gut, such as stretching or distension. These normal events may be uncomfortable or quite painful in people with IBS. Around 60% of people with IBS are thought to have a highly sensitive gut wall.

Alterations in the gut microbiota

The gut microbiota refers to the complex community of microorganisms that live within the gut of humans. Although we still do not know whether our gut bacteria cause IBS, some research has shown differences between the microbiota of people with and without IBS.

Other possible causes of IBS

Other possible causes of IBS include inflammation in the intestine or possibly, a more permeable or ‘leaky’ gut wall.

Symptoms of IBS Abdominal pain

Most people with IBS experience abdominal pain, and usually, this is felt in the lower abdomen. The pain can be crampy or sharp, stabbing or dull and can last minutes or hours. Often, abdominal pain will be made better or worse by defection (doing a poo). It can also be linked to a change in bowel habit.

Bloating and distension

Bloating and distension are common, bothersome symptoms in IBS. Bloating refers to a sensation of abdominal swelling. Patients will sometimes describe this feeling as an inflated balloon in the belly. By contrast, abdominal distention refers to an actual increase in abdominal circumference (sometimes called abdominal girth).

Because abdominal bloating and distension are different symptoms, they can occur together or separately.

People who suffer bloating and/or distension often report that these symptoms:

  • get worse over the day;
  • get worse with meals;
  • improve overnight.


Constipation is a common problem in IBS. People who suffer constipation often experience:
  • Difficulty passing a bowel motion (straining)
  • A feeling that the bowel is not properly emptied after a bowel motion
  • Hard or lumpy stools
  • Infrequent bowel motions
  • Sensation of blockage in the anus and/or rectum
  • Use of the fingers to remove stool

When constipation is present, this can make other IBS symptoms worse, such as abdominal pain, excessive gas, bloating and/or distension.


Loose or watery bowel motions are common in IBS. If diarrhoea is present, this can result in more frequent/urgent bowel movements. In severe cases, diarrhoea can result in incontinence.

Will I have IBS forever?

IBS is considered a chronic condition, which means it is usually present over the long-term. However, IBS symptoms often come and go over time. Symptoms may improve or disappear for a time, and then return, or new symptoms may develop. Symptoms may also change from being quite mild, to sometimes being quite severe. Some people also find that their usual bowel habit (e.g. diarrhoea or constipation) changes. For example, they may suffer mostly constipation or mostly diarrhoea for a while, and then develop more of a mixed bowel habit, (sometimes experiencing diarrhoea and sometimes experiencing constipation).

Getting a diagnosis of IBS

IBS should not be ‘self-diagnosed’. Instead, if you suspect you have IBS, see your medical doctor for a proper diagnosis. Getting a diagnosis is important to rule out other more serious conditions, such as coeliac disease, inflammatory bowel disease and endometriosis. Your doctor can run tests to rule these conditions out. Once you are diagnosed with IBS, you can choose treatments that are best targeted to your condition.

Symptoms to tell your doctor about

There are certain symptoms that are considered ‘red flags’ or ‘alarm features’ in IBS. This is because they are sometime present in more serious conditions, such as coeliac disease or inflammatory bowel disease. If you experience any of the following symptoms, make sure you tell your doctor:
  • Blood in the stool
  • Anaemia
  • Weight loss that is unintentional
  • Fever
  • Symptoms that are severe or getting progressively worse
  • Daily diarrhoea
  • Bowel motions at night
  • Having a family history of other bowel diseases

Your doctor may want to run additional tests to rule other conditions out if you suffer any of these symptoms.

Tests for IBS

The type and number of tests needed to diagnose IBS can vary quite a lot between individuals. If your doctor identifies no symptoms that he or she is concerned about (such as blood in the stool or anaemia), few (if any) tests are needed to confirm a diagnosis of IBS. However, sometimes additional tests are needed to rule out other conditions (such as coeliac disease) and to confirm the diagnosis of IBS. Common tests can include:
  • Blood tests
  • Stool tests
  • Gastroscopy/colonoscopy

Unreliable tests for IBS

There are also many tests that are widely available, but not helpful in diagnosing IBS. These include:
  • Breath tests
  • IgG food intolerance tests Faecal microbiota testing 
We do not recommend the use of these tests.

IBS Treatment

There are a large number of treatments available to manage IBS symptoms. These treatments will not cure IBS, they simply help relieve the symptoms of IBS. Some of these treatments are well supported by scientific evidence, and others are not. Working with your doctor or dietitian will help you to identify a treatment that is best suited to your main symptoms and the underlying cause of these symptoms. You may need to try several different treatments before you find one that suits your lifestyle and improves your symptoms. But remember, when trying different treatments, try only one at a time. This will give you the clearest picture about which treatments are working, and which are not.

You may be advised to begin by trying non-drug therapies. These are generally better at improving a range of symptoms, whereas drug therapies tend to target specific symptoms. An advantage of non-drug therapies is that they can often be used long-term, without ongoing costs, with few risks, and sometimes, with minimal health professional input.

Below is a list of therapies sometimes used to manage symptoms of IBS.

Diet Therapies, for example:
  • Low FODMAP diet
  • Gluten free diet
  • Modifying fibre intake – via dietary changes or supplements
  • Fat restricted diet
  • Coffee and caffeine restriction
  • Alcohol restriction
  • Restriction of spicy foods
  • Prescription medications such as antispasmodics, antidepressants, prosecretory agents, anti-diarrhoeal agents, antibiotics, serotonin agents
  • Over the counter medications, such as peppermint oil, laxatives and probiotics
  • Exercise
  • Gut directed hypnotherapy
  • Cognitive behaviour therapy
  • Stress management

What is the best diet for IBS?

Research at Monash University and numerous other centres around the world has shown that a low FODMAP diet improves IBS symptoms in around 3 out of 4 IBS sufferers. Because of this, a low FODMAP diet is recommended as the first treatment choice for people with IBS. To learn more about FODMAPs and the 3-step FODMAP diet, click here.