This information is approved and/or reviewed by U-M Health System providers but it is not a tool for self-diagnosis or a substitute for medical treatment. You should speak to your physician or make an appointment to be seen if you have questions or concerns about this information or your medical condition.| Complete disclaimer
Hydrogen Breath Test
What is a hydrogen breath test?
This is a test for bacterial overgrowth, or intolerances to lactose, fructose, or sucrose. Glucose is a sugar that will be broken down by bacteria if present in the small bowel with hydrogen or methane gas as a by-product. The breath sample will be analyzed for hydrogen or methane content to determine if you are able to properly break down the lactose, fructose, or sucrose, or if you have bacterial overgrowth.
What can I expect from a hydrogen breath test?
This test requires that you drink a solution of lactose, fructose, sucrose, or glucose in water. Lactose is the sugar found in milk and is normally broken down in the small bowel. Glucose is a sugar that will be broken down by bacteria if present in the small bowel with hydrogen as a by-product. Sucrose is a common sugar found in foods such as candy. After drinking the solution, you will be asked to breath into a plastic bag. Breath samples are obtained every 15 minutes for adults, and every 30 minutes for children. The breath sample will be analyzed for hydrogen content to determine if you are able to properly break down the lactose or sucrose, or if you have bacterial overgrowth. The test lasts about 2 hours for glucose and 2 to 3 hours for lactose, fructose, and sucrose. The test is performed in the Gastroenterology Physiology Laboratory of the Medical Procedures Unit.
How do I prepare for a hydrogen breath test?
Please follow these instructions to ensure a successful test.
YOU MUST BE OFF ANTIBIOTICS AND PEPTO-BISMOL FOR TWO (2) WEEKS.
On the evening before your hydrogen breath test, you may have the usual amounts of meat and vegetables from dinnertime until midnight. Please have only small amounts of sugar and starch, such as bread, pasta, and cake. After midnight, do not eat, drink, or smoke until your examination is completed. THIS INCLUDES ANY TYPE OF GUM OR CANDY.
Please note: breath tests can be done anytime before a colonoscopy prep; but not for four (4) weeks after a colonoscopy prep, or any test that requires a bowel prep.
Can I take my medications before a hydrogen breath test?
Do not take any medication, including over-the-counter medication, unless your physician or nurse has advised you otherwise. Other critical medications, such as those for your heart, blood pressure, breathing, or seizures, should be taken with sips of water only on the morning of the procedure unless you are instructed to do otherwise by your doctor.
If you are unable to keep your appointment please call the Gastroenterology Physiology Laboratory in the Medical Procedures Unit at (734) 936-9250, option 2.
Web sites affiliated with the University of Michigan Health System:
Department of Internal Medicine Division of Gastroenterology
Directions to the Medical Procedures Unit
Instructions for Patients with Diabetes Having Outpatient Tests (on insulin)
Instructions for Patients with Diabetes Having Outpatient Tests (no insulin)
Other related Web sites:
National Institute of Digestive Diseases – Lactose Intolerance
Your Digestive System and How it Works