Small intestinal bacterial overgrowth (SIBO) breath test

What’s the test for?

The breath test detects hydrogen and methane and is used to detect abnormal growth of bacteria in the small intestine, or small intestinal bacterial overgrowth (SIBO).

You may be referred for this test if you are experiencing symptoms including diarrhoea, nausea, bloating, gas and abdominal cramps.

About the procedure

You will provide an initial breath sample by blowing into a test tube through a straw or into a foil bag. This will give us your baseline reading.

Then, you will drink water containing either glucose or lactulose which needs to be consumed over a minute or two.

Breath samples then need to be taken every 15 minutes for two hours and 15 minutes.

During the test, you should take note of any symptoms you experience and complete the symptom form.

How to prepare

There is some preparation required before your arrival at the clinic. This preparation involves stopping certain medication and fasting. Please see our patient information leaflet for full details.

What can be learned

Bacteria normally found in the large intestine produce hydrogen and methane through fermentation of carbohydrates/sugars. In SIBO, these bacteria move into the small intestine, meaning they break down the sugars before the body has had chance to digest them.

This causes an over-production of gases such as hydrogen and methane. These gases are absorbed into the bloodstream and transported to the lungs. They are then exhaled by the lungs and can be collected in breath samples for analysis.

Following your test, your data will be analysed, and results written up into a report. The report will be sent to both you and your referring consultant/doctor, who will explain the results to you in a follow-up consultation.

Information leaflet
Information leaflet

Find more information about this test using our PDF download.

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Breath test information

Breath test information

This test can be done in-clinic or at home.

Friendly and caring staff – thank you.

Manchester Patient