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:
- Eat a LOW CARBOHYDRATE DIET. The purpose of this diet is to avoid foods that may produce gas in the intestinal tract for two days before your test, as this could cause inaccurate test results.
THE DAY BEFORE your test:
Allowed Avoid Grains/starches Rice, quinoa, potato, oatmeal, corn tortillas, popcorn, gluten free bread/crackers/pasta. Cereal: plain cheerios, plain rice/corn chex, corn flakes, rice krispies Wheat products (including bread, pasta, crackers, cookies, cake, cereal, flour tortilla), rye, barley Vegetables Bell peppers (any color), carrots, chives, cucumber, eggplant, green beans, kale, lettuce, olives, parsnip, spinach, summer/winter squash, zucchini, tomato
Limit to ½ cup portion: beets, butternut squash, broccoli, Brussels sprouts, corn, fennel bulb, green peas, sweet potato
Artichoke, asparagus, cauliflower, garlic, leeks, mushrooms, okra, onion/shallots, snow peas, sugar snap peas Fruit Banana, blueberry, cantaloupe, cranberry, grapes, honeydew, kiwi, lemon, lime, orange, papaya, pineapple, pomegranate, raspberry, strawberry Apple, apricot, blackberry, cherry, dried fruit (raisins), grapefruit, mango, nectarine, pear, peach, plum, prunes, watermelon Proteins Meat, eggs, fish, tofu, most nuts (see “avoid” column), peanut butter, almond butter Beans, hummus, edamame, cashews, pistachios Dairy Lactose-free milk/yogurt/ice cream, rice milk; any aged or hard cheese (including cheddar, provolone, swiss, parmesan, feta, goat, etc) Milk, yogurt, ice cream, cottage cheese, ricotta cheese, soy milk, almond milk Beverages Water, coffee, tea, sugar-free beverages (crystal light, diet pop) Regular soda and other beverages with high-fructose corn syrup Sweeteners Pure maple syrup, sugar substitutes (such as Stevia), table sugar Agave, honey, high fructose corn syrup
Breakfast: 2 scrambled eggs and 1 banana
Lunch: salad with grilled chicken, tomato, cucumber, carrots, feta, balsamic vinegar + olive oil dressing
Snack: 1 cup fruit (such as blueberries and strawberries), small handful of peanuts or almonds
Dinner: Grilled chicken, baked potato, ½ cup steamed broccoli
Snack: 1 cup popcorn
Breakfast: plain cheerios with lactose-free milk (such as Lactaid brand) or oatmeal with cinnamon and blueberries
Lunch: sandwich with turkey, cheese, lettuce, and tomato on gluten-free bread; plain potato chips or 1 orange
Snack: baby carrots and 1 cheese stick
Dinner: grilled salmon with lemon, brown rice or quinoa, sautéed zucchini and yellow squash
Snack: 1 cup grapes
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.
If you are unable to keep your appointment, please call the Medical Procedures Unit at (734) 936-9250, option 1.
Websites 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 Websites:
National Digestive Diseases Information Clearing House – Lactose Intolerance