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  • Dr. Erhart and Dr. Heer in the waiting area

    Hydrogen breath test

    What you need to know:

Dear Patient,

You have been referred to us by your doctor for a hydrogen breath test. We would like to explain how this procedure works and what you need to know as a patient: A hydrogen breath test is a diagnostic procedure in which we analyse your exhaled air. This can help us diagnose various gastrointestinal disorders – depending on the starting situation we will perform a hydrogen breath test to identify lactose intolerance, fructose malabsorption or bacterial overgrowth.


You need to have an empty stomach for the examination and must not smoke (6 hours before the test), chew chewing gum (or any sweets), or perform any oral and dental hygiene that morning. On the day before your appointment you will be asked not to eat specific food such as milk, yoghurt, fruit, juices, vegetables that cause bloating, eggs, legumes, alcohol or sweetened foods. Instead, we ask you to eat meals containing fish, rice, noodles, asparagus, lactose-free dairy products, white bread, still water and tea on the day before your appointment. Nuts, carrots, courgettes, avocado and tomatoes are permitted in small amounts. On the day before, please finish eating by 5 pm and fast after this (last meal 14 hours before the start of the test). Drinking is permitted until midnight before your examination (still water and tea only). If you need to take medication on the day of the examination, please bring this with you to your appointment at our practice. If you are unsure about anything, please get in touch with us. One week before your appointment you need to stop taking any laxatives or H2 blockers.
Two weeks before your appointment you need to stop taking any proton pump inhibitors (PPI). Please note that taking antibiotics changes your intestinal flora. Your appointment for a hydrogen breath test should therefore take place no earlier than 4 weeks after completing a course of antibiotics. Equally, you should not undergo a colonoscopy four weeks before testing as the laxative measures also change the intestinal flora.


At your hydrogen breath test appointment you will drink a sugar solution over a period of three hours. At regular intervals we will take a breath sample and measure its hydrogen concentration. Please bring some reading material with you to pass the time.

062 287 80 60