Hydrogen/Methane Breath Testing

Please Note: This service is currently unavailable.

What is breath testing?

The hydrogen/methane breath test is a painless and non-invasive way to diagnose the malabsorption of different carbohydrates known to cause Irritable Bowel Syndrome (IBS) symptoms.

How do these carbohydrates cause IBS?

A large proportion of Australians poorly absorb these carbohydrates. Instead of being absorbed by the small intestine, the carbohydrates move to the large intestine, ferment and trigger the unpleasant symptoms of IBS.

How does breath testing detect malabsorption?

During this reaction, the bacteria in your large intestine produces either hydrogen or methane gas (or sometimes both). The gas is absorbed into the bloodstream and moves to the lungs where it is breathed out and detected by the breath testing machine.

Malabsorption of the carbohydrates such as lactose, fructose and sorbitol is indicated by an increase in above baseline levels in the breath hydrogen or methane gas.

Small Intestine Bacterial Overgrowth

The hydrogen/methane breath test can also diagnose suspected small intestine bacterial overgrowth (SIBO). In someone with SIBO, sugars such as glucose are fermented by bacteria in the small intestine, and produce the increase in the breath hydrogen or methane measured.

Tests and potential outcomes

A positive diagnosis is made based on your breath test results and any symptoms you may experience in reaction to the substrate.


Each test

  • Starts at given appointment time and takes up to 3.5 hours to complete
  • Needs to be done on a separate day and at least three days apart
  • Requires pre-test preparations – see “Test Preparation”


  • All tests are payable on the day by EFTPOS, Visa or MasterCard, or Cash.
  • Discount provided for Health Care Card holders
  • There is no Medicare rebate. All tests are safe in children and pregnancy. If your child is under 35kg in bodyweight, then please advise booking staff of approximate bodyweight.

Test Preparation

You must follow these instructions before each test to ensure accurate and reliable results. This will be verified on the day in order for your test to proceed. Patients who do not follow these instructions may be refused testing or may have to reschedule.

Breath Testing

Diet 24 hours before-hand

If you’re unsure whether you can eat a particular food, please feel free to call us and check!

Breath Testing

Meal Suggestions

Breath Testing

Foods to avoid

Breath Testing

Breath test patient information Low FODMAP diet