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 breathe 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 for glucose lasts about 2 hours and the tests for lactose, fructose, and sucrose last about 2 to 3 hours. The test is performed in the Gastrointestinal 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.
TWO WEEKS BEFORE your test:
YOU MUST BE OFF ANTIBIOTICS AND PEPTO-BISMOL FOR TWO (2) WEEKS.
TWO DAYS BEFORE your test:
- You should eat a LOW CARBOHYDRATE DIET (see below).
THE DAY BEFORE your test:
You should have NOTHING BY MOUTH 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.
Before starting the test you will be asked to rinse your mouth with mouthwash. This limits the effect of bacteria in your mouth on the results.
Can I take my medicine before a hydrogen breath test?
- Critical medicines, such as those for your heart, blood pressure, breathing, or seizures, should be taken with sips of water on the morning of the procedure. Noncritical medicines, including over-the-counter medicines and supplements should not be taken, unless your physician or nurse has advised you otherwise.
Re: Low carbohydrate diet
- Foods containing added sugars
- Sugar-sweetened beverages
- Pasta, breads, grains, cereals, potatoes
- Milk and milk products
- Focus on:
- Proteins - including meat, eggs, poultry, fish.
If you are unable to keep your appointment, please call the Medical Procedures Unit at (734) 936-9250, option 1.
Web sites affiliated with the University of Michigan Health System:
Your Digestive System and How it Works
Directions to the Medical Procedures Unit – Look for number 24 on the floor plan.
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 Digestive Diseases Information Clearing House – Lactose Intolerance