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Breath Test

Medically reviewed by Last updated on Dec 2, 2022.


What you need to know about a breath test:

A breath test measures the amount of certain gases produced in your digestive system. The test may be used to diagnose conditions such as carbohydrate (lactose or fructose) intolerance, bacterial overgrowth syndrome, or H. pylori infection.

How to prepare for a breath test:

Your healthcare provider will tell you how to prepare for your test. Directions will depend on the test you need. Your provider may tell you not to eat or drink anything for a certain time before your test. Your provider will tell you if it is okay to brush your teeth on the day of your test.

  • Tell your provider about all your current medicines. Your provider will tell you if you need to stop any medicine for your test, and when to stop. Your provider will tell you which medicines to take or not take on the day of your test.
  • If you are having a carbohydrate intolerance or bacterial overgrowth syndrome test:
    • Do not use laxatives or enemas within 3 days of your test.
    • Do not have high-fiber foods or fiber supplements within 24 hours of your test.
    • Do not smoke, use an E-cigarette, or exercise for at least 1 hour before your test.
    • Do not chew gum or use mouthwash right before your test.

What will happen during a breath test:

  • You will breathe in deeply and then exhale into a container that looks like a bag. Then you will drink a liquid. You will breathe in deeply and exhale into the container again 15 to 30 minutes after you drink the liquid.
  • Breath samples will continue every 15 to 60 minutes for 3 to 5 hours. Samples may only be collected 2 times over 20 to 30 minutes to test for H. pylori infection.
  • Do not sleep, smoke, or exercise during the test. These could affect your test results.
Breath Test

What to expect after a breath test:

  • You will be able to do your regular daily activities right after your test.
  • Your healthcare provider will tell you when you can have your regular foods and drinks.
  • Follow up with your provider as directed to get your test results.
  • You may be given antibiotics if your results show you have an H. pylori infection. You may need to have another breath test to make sure the infection is gone.
  • You may need other tests if you continue to have symptoms but the test did not find a cause.

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The above information is an educational aid only. It is not intended as medical advice for individual conditions or treatments. Talk to your doctor, nurse or pharmacist before following any medical regimen to see if it is safe and effective for you.

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Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.