Hydrogen/Methane Breath Testing

Hydrogen and Methane Breath Testing for Gastrointestinal Disorders

A Hydrogen / Methane Breath Test is a painless and non-invasive test which helps to diagnose the following gastrointestinal disorders.

  • Lactose Breath test for lactose intolerance (lactase deficiency)
  • Fructose Breath test for fructose malabsorption
  • Glucose Breath test for small bowel/intestinal bacterial overgrowth
  • Lactulose Breath test for Hydrogen production and intestinal transit time
  • Sucrose Breath test for sucrose malabsorption (sucrase-isomaltase deficiency)
  • Sorbitol Breath test for sorbitol malabsorption
  • Mannitol Breath test for mannitol malabsorption

How does the breath test work?

A wide range of sugars we ingest everyday, such as lactose and fructose, are usually absorbed within the small bowel. A large proportion of people absorb these sugars poorly, allowing the sugars to pass into the colon, or large bowel. Fermentation of incompletely absorbed sugars within the colon may result in the symptoms typical of irritable bowel syndrome (IBS), such as bloating, abdominal pain, excessive wind, diarrhoea, constipation, or a mixture of both.

The breath test is based upon the fact that bacteria within the large bowel produce either hydrogen or methane gas (or a combination of both) when ingested sugars are not completely absorbed by the small intestine.

The gas is absorbed into the bloodstream from the bowel and travels to the lungs where it is breathed out, allowing detection by hydrogen or methane breath testing. Malabsorption of an orally-ingested sugar such as lactose or fructose is indicated by a significant increase above baseline levels in breath hydrogen or methane.

In patients suspected of having small bowel bacterial overgrowth, gas producing bacteria are also found in the small intestine. In this case orally-ingested sugars such as glucose are fermented by bacteria in the small intestine before they can be absorbed leading to an increase in breath hydrogen or methane.

The lactulose control test

Some patients are thought not to produce hydrogen in large amounts, so called “low-hydrogen producers,” and may instead produce other gases such as methane. In addition, some patients may produce sufficient amounts of hydrogen, but it is quickly metabolised to produce methane. Both of these situations may result in a patient with true sugar malabsorption having a “false-negative” hydrogen breath test, that is, being told they don’t have sugar malabsorption when in fact they do. The rate of low-hydrogen producers quoted in the medical literature ranges from 5-43%.

In order to maximise the accuracy and information obtained from a breath test, we believe it is important to have a baseline lactulose hydrogen breath test. This test will enable our gastroenterologists to determine whether the bacteria within your bowel predominantly produce either hydrogen or methane gas, thereby allowing us to perform subsequent tests measuring the most appropriate gas for you. In addition to this, the lactulose control test allows us to accurately measure the oro-caecal transit time, which is the time it takes for the sugar to pass from your mouth to large bowel. As this time varies significantly between different people, knowing your personal transit time allows us to tailor the duration of subsequent tests specifically for you.

As way of quality control, Gastrolab continues to monitor the latest research developments and as such procedures and protocols reflect current best practice and are subject to change over time.

Further information:

Patient Information:

For Patient Information, including detailed information and to watch a VIDEO about what happens during the test and our recommendations for test preparation, please read:
- Hydrogen/Methane Breath Testing Patient Instructions