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preparing for breath hydrogen test

what is a breath hydrogen test?

A breath hydrogen test measures hydrogen in the breath. It is used to diagnose one of the following two conditions that can cause abdominal (stomach) pain, cramping, bloating, gas or diarrhea.

  1. A condition in which dietary sugars are not digested normally, such as milk sugar (lactose), fruit sugar (fructose) or table sugar (sucrose). 
  2. An overgrowth of bacteria in the small bowel, causing food and nutrients not to be absorbed properly. This can be caused by eating/drinking lactulose or glucose. Lactulose testing can give information about how long it takes food/drink to move through the small intestines to the colon.

how do I prepare myself/child for the test?

For two weeks before the test:

  • No antibiotics or probiotics. If prescribed antibiotics within four weeks of date of test, you must call to reschedule.
  • No colonoscopy, barium enema or tests requiring bowel prep or cleansing.
  • If you have diabetes, talk to your doctor about how to take your medication the day of the test.

24 hours before test:
Limit your foods to those below. These are foods you CAN eat:

  • Baked or broiled chicken, fish or turkey (salt and pepper only)
  • Clear chicken or beef broth (no vegetable pieces)
  • White bread (only)
  • Plain steamed white rice
  • Eggs
  • Drink only water. - Do not take fiber supplements or laxatives.
  • Avoid sugars, dairy and slowly absorbed carbohydrates like bread, potato, beans, bran or fiber.

12 hours before test (for example, 8:00 pm-8:00 am)

  • Do not eat or drink anything, except water.

The day of the test:

  • 2 hours before the test: Use small amount of water to brush your teeth and take medication.
  • 2 hours before and during the test: DO NOT sleep, exercise, smoke or be exposed to second-hand smoke, chew gum or tobacco, or eat hard candy.

what happens during the test?

A breath sample will be collected by blowing into a balloon-type bag (a face mask will be used for a small child) and injected into an analyzer. Next, the patient will drink a small amount of solution of lactulose, glucose, lactose, sucrose or fructose. Exhaled breaths will be collected and analyzed over the next 3 to 3.5 hours.

what happens after the test?

You may return to your usual diet and activity. A gastroenterologist will read the results and send them to your doctor.

what do I need to bring to the test?

Please bring your child’s bottle or favorite sippy cup. The test takes a few hours, so bring items that will help fill the time for you and your child.

where do I go when I arrive to Dayton Children’s?

This test is done at our main campus in Dayton. You must arrive at reception area 1C at least 20 minutes earlier than your scheduled appointment time to allow for check-in. The registrar will let us know you’re here.

what if I need to reschedule or have questions?

  • To reschedule, call central scheduling:  937-641-4000 
  • For questions about the test, call pulmonary diagnostic lab: 937-641-4068


contact us schedule an appointment

The pulmonary department’s triage nurses are available by phone at 937-641-3376 from 8:00 a.m. to 5:00 p.m. Monday through Friday to answer patient questions . After hours, call 937-641-3000 to reach the hospital’s operator and ask for the pulmonologist on call.

New patients - visit our appointment scheduling page

All follow up appointments will be made during your clinic visit or by calling central scheduling at 937-641-4000.