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How to prepare for a breath hydrogen test

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The day before (6 a.m. to 4 p.m.)

Please do not eat anything other than the list of acceptable foods. Prepare food without any oils, butter, sauces, buns, or breading. If this diet is not followed, we may not be able to complete the test. You can use a bit of salt and pepper only.

Acceptable foods

  • Plain beef, chicken, pork, fish, tofu, poached or boiled eggs (no sauces or marinades)
  • White bread, white pasta, and white rice (ensure there is NO added fiber in all products)
  • Vegetables (must be peeled): carrots, zucchinis, peppers, potatoes and peeled cucumbers
  • Fruit: oranges, cantaloupe and  ½ cup of tomatoes
  • To drink: unsweetened rice milk, water

The evening before (4 p.m. to 8 p.m.)

Acceptable foods

  • Plain ground beef, plain skinless chicken or turkey breast, plain tofu
  • Boiled or poached eggs
  • Plain white rice
  • To drink: unsweetened rice milk, water

The night before (8 p.m. onward)

  • Do not eat anything
  • Do not drink fluids (except water)
  • Do not smoke (even secondhand smoke) or vape
  • Do not do any vigorous exercise

Morning of the test

Do not:

  • eat breakfast
  • brush your teeth
  • chew gum
  • use breath mints

What to expect during the test

  • The test will take between 3 - 4 hours to complete 

  • First, we will provide you with mint mouthwash to gargle and clean your mouth 

  • Once you’ve provided a baseline breath, we will provide you with a solution of either lactose, fructose, or glucose. You’ll have 5 minutes to drink this. 

  • Then every 20 min – 30 min for the next 3 - 4 hours you will provide breath.

  • Please report any symptoms of bloating, vomiting or diarrhea to the nurse.

Do not: 

  • Eat food 

  • Drink fluids (water is ok) 

  • Smoke or vape 

  • Do any vigorous exercise 

  • Sleep 

Important information

  • Your test will begin at 7:45 am on the day that it is scheduled.  
  • If you use antibiotics within four weeks of the test, it will need to be rescheduled. 
  • If you performed colonic cleansing for a scope, the test will need to be rescheduled. 
  • Stop probiotics, prokinetics (e.g. metoclopramide, domperidone) 24 hours before the test, and laxatives (e.g. Restorolax, Senokot, lactulose, fleet enema, docusate sodium), 24 hours before the test.  
  • If you test positive the clinic will contact you with further instructions.

Do not eat the following foods:

  • Legumes (chickpeas, lentils, beans, etc.) 
  • Whole grain products (bran cereal, whole wheat bread, etc.) 
  • Vegetables such as spinach, broccoli, cauliflower, cabbage, Brussel sprouts, onions, and garlic.  
  • Fruits such as dried raisins, prunes, figs and dried apricots 
  • Nuts and seeds 
  • Milk, almond milk, yogurt, cheese, creams 
  • Butter, oils, and margarine 
  • Ketchup, mustard, mayonnaise, gravy, sauces, soya sauce 
  • Juice, coffee, and tea

Contact us with any questions or concerns. 
If you need to reschedule the appointment or cancel, please contact the breath hydrogen line at 613-737-7600 ext. 1538. You can also reach the nurse directly through MyChart.
#BestLife for every child and youth

2025-06-17 | P6195

This reference is for educational purposes only. If you have any questions, ask your health-care provider.

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