Hydrogen Breath Testing for Small Bowel Bacterial Overgrowth

Hydrogen breath testing is being used for assessment of the presence of bacterial overgrowth in the small bowel. The test is safe and does not cause any discomfort.


For two (2) weeks before:

  • Antibiotics, pro-biotics, and bacterial cultures (including yogurt) must be discontinued for 14 days prior to testing ANTIBIOTICS may alter the results of this test. If for any reason you are required to take otc antibiotics, please contact us to rebook your appointment.

For one (1) week before:

  • Do not take any LAXATIVES OR STOOL SOFTENERS or stool bulking agents (for example, Metamucil or Citrucel).
  • Do not undergo any test that requires cleansing of the bowel, such as a colonoscopy or barium enema.

The day before:

  • Have an early dinner (No later than 6PM).
  • You may consume only the following foods and drinks; plain white bread, plain white rice, plain white potatoes, baked or broiled chicken or fish, water, non-flavoured black coffee or tea.
  • Only salt may be used to flavour food. Soda pop/cola drinks are not permitted. Specifically avoid gas producing food such as beans, pasta, fibre cereals, and high fibre foods.


At 8 pm the day before until after your test:

  • No SMOKING starting at 8:00PM the night before testing until the test is completed.
  • Continue to take your prescription MEDICATIONS until 12 hours before the test.

You may have nothing to eat after midnight the night before your test. Small amounts of water are permitted.

The day of the Test:

  • Take no MEDICATIONS the morning of your test. Bring all prescription medications to the appointment.
  • Please be advised that this test requires the consumption of Glucose products. If you are a diabetic, please bring your insulin with you to your test and advise clinic staff on admission.


Testing will begin with the initial sample of exhaled breath called the baseline sample.

  • The patient will exhale into the collection bag (before ingestion of glucose) at 8:30 am
  • By 8:35, the patient will drink the 75g Glucose/water solution (ensuring that it is all consumed within a 2 minute time frame).
  • Breath samples will be taken every 15 minutes for over a period of 2 hours
  • DURATION – testing may take up to 3 hours to be completed

Small amounts of water are permitted during your test but not immediately prior to your breath samples

Referring Physicians