Hydrogen Methane Breath Test

What is Hydrogen Methane Breath Test

When mentioning to patients about tests for gut disorders, endoscopy, blood and stool assays spring into mind. However, what is bubbling in your gut now offers potentially new insights into common disorders of the gastrointestinal tract (GI). Therefore, hydrogen-methane breath testing can be considered to help diagnose several conditions that cause GI symptoms and certain digestive problems.


Breath testing involves measuring the volume of gases produced inside the small intestines of the gut, following the administration of a test substrate. Hence, the idea of deep lung (alveolar) gas sampling. The concept is that gases produced in the gut diffuse into the bloodstream, and diffuse out again through the alveoli in the lungs into the exhaled air, where it can be easily collected and measured.

The gases of interest are hydrogen and methane. These are produced by the microbes in our gut, as a metabolic by-product of carbohydrate fermentation in the intestine. When these gases are detected in the breath, it provides information to learn more about your digestive health. For instance, if you are intolerant to or are unable to digest certain sugars or there is an abnormal growth of bacteria within the small bowel.

WHEN Should I Get The Procedure

If there is a clinical suspicion of a diagnosis of a small intestine bacterial overgrowth (SIBO), lactose or fructose intolerance, your doctor will refer you to one of our medical staff to get a breath test.

By manipulating the “food” (otherwise known as a substrate) the gut bacteria receives, we can measure the gases of interest and pinpoint the underlying cause of the patient’s GI symptoms. Currently, the two with clinical applicability are small intestinal bacterial overgrowth (SIBO) and FODMAP intolerances.

PREPARING For The Procedure

Preparation involves adhering to a special diet for a few days prior to the test, as well as fasting after dinner on the night before the test. A detailed advice sheet will be administered once you have been listed for the test by your doctor.

BEFORE The Procedure

There are a few special requirements to note when you are scheduling a test date:

  1. No antibiotics in the 2 weeks prior
  2. No colonoscopy or colon cleansing for 4 weeks prior

These will affect the intestinal microflora and hence the test accuracy.

Do inform our staff and your doctor so the test date can be fixed accordingly.

DURING The Procedure

It is a simple, non-invasive test which involves the patient drinking a sugar drink before taking a baseline breath sample at regular intervals for 3 hours in our clinic. You will be required to remain in the clinic for breath collection at intervals and blow into a special collection device. During the test, the patient is to report any symptoms experienced.

For example, samples are taken at 20 mins intervals for SIBO and 60 mins for lactose. The levels of hydrogen and methane are sequentially tracked and plotted by our Neuro-gastro motility specialist to measure the levels of hydrogen and methane present in the breath.

When ingested sugars are not completely absorbed, bacteria within the large bowel produce hydrogen and/or methane gas that will be detected in the breath test. The poor absorption of an orally ingested sugar is indicated by amounts larger than normal and above baseline levels of exhaled hydrogen or methane in your breath.

AFTER The Procedure

The results are available within 2-3 days. Your doctor will be able to evaluate conditions such as lactose intolerance or other digestive disorders and present effective treatment options as well as personalised recommendations for your digestive health.

SAFETY Of The Procedure

The substrates (or food used to feed the bacteria) are common food sugars that are readily available. There is no additional risk involved in this test.

QUALITY Of The Procedure

Patients often worry if the breath exhaled is adequate or if there is any atmospheric gas contamination.  The testing system corrects any errors or variance.