Hydrogen-Methane Breath Test Preparation

for Bacterial Overgrowth & Sugar Malabsorption Testing

The breath test for bacterial overgrowth enables a prediction of the likelihood that you have excessive bacteria growing in your intestine. Large amounts of bacteria compete for nutrients which will not allow the body to absorb enough nutrients. The breakdown of nutrients by the bacteria can also damage the cells lining the intestinal wall.  The gas produced by the bacteria can cause digestive symptoms.  It is absorbed into the bloodstream and exhaled on the breath. In the case of fructose or lactose malabsorption, the undigested sugars travel to the large intestine where excessive fermentation causes symptoms. Both of these sugars are normally absorbed in the small intestine.

The procedure involves fasting (not eating or drinking) before the test and then drinking a dose of a challenge sugar dissolved in water. Breath samples are collected every 20 minutes for 3 hours (10 samples in total). For sugar malabsorption testing, samples are collected hourly over a 3-hour testing period.


We strongly recommend you watch this video, which goes through test preparation and sample collection.The hydrogen breath test cannot be done following a colonoscopy, barium enema, or any tests that require a bowel prep to be given. The bowel prep will cleanse the bacteria.  You will need to wait at for least 2 weeks after the procedure to collect your breath samples.

Two weeks before the test

No antifungals or antibiotics by mouth or IV (ear, nose, eye and skin applications are OK)

One week before the test

No proton-pump inhibitors (eg Losec)
If you experience severe diarrhoea in the week prior to the test, please inform us before starting the test.

Two days before the test

Follow a low-fibre, lactose-free diet.

The day before your test

  • A restricted diet is required.  A guideline and meal ideas can be found here
  • NO Fibre Supplements (eg. Metamucil®).
  • NO Laxatives or medications that slow the bowel, such as Lomotil or Imodium
  • Do not eat after 8 pm. You may drink water.
  • Do not smoke for six hours prior to the test.

The day of the test

Get up an hour before you want to start collecting your breath samples. Clean your teeth straight away.  You may drink water only.

Do not exercise, smoke or chew gum in the hour prior to the test.

Follow the instructions sent to you, being careful to note the time on the label for each tube, along with your name, the date etc.

If you have any questions or concerns you may contact us on 09 846 5566 OR

Send us a message

9 + 6 =