Using a Gastrolyzer to Prepare Patients for a Hydrogen and Methane Breath Test

This article discusses a suggested protocol for patients preparing to take a Hydrogen and Methane breath test using a Gastrolyzer.

Four weeks prior to test

  • Patients have to ensure avoiding consumption of antibiotics within the four weeks before performing the test
  • Patients can experience contraindications if they have a colonoscopy within four weeks before undergoing the test
  • Patients can experience contraindications if they have a fluoroscopy within four weeks before undergoing the test

One week prior to test

  • Stool softeners or hardeners should not be used
  • Vitamins or supplements consisting of lactose fillers or fructose flavorings should not be taken
  • Fiber supplements, Bismuth subsalicylate or Imodium should not be taken
  • Pre and probiotics should be avoided
  • Hydrogen blockers and proton pump inhibitors should be avoided

Three days prior to test

The following diet should be followed for up to 3* days before the test, showing foods to avoid and a recommended diet to be followed for the time before fasting. If patients are not sure whether or not to avoid a food, it is recommended to avoid the food to ensure it does not interfere with test results.

Foods that should be avoided include:

  • Vegetables
  • Milk and dairy products
  • Grains and cereals
  • Fruit and fruit derivatives
  • Nuts, seeds and beans
  • And any beverages and foods consisting of high fructose corn syrup and honey, mayo, mustard, ketchup, sugar-free foods, etc.

Suggested foods to be undertaken include

  • Plain steamed white rice
  • Water
  • Eggs
  • Grilled or backed chicken, fish or turkey with low amounts of salt for flavoring only
  • Eggs
  • Water

*Minimum of 24 hours of the suggested diet is required. If patient suffers from constipation, 2 or 3 days is preferred as gut transit time is slower.

12 hours prior to test

Patients will observe a minimum of 12 hours of fasting before taking the test. They should not consume anything other than water. They should not take any medications on the morning of their test, but should take all prescription medicines to their morning appointment.4,5

Note: If you are a diabetic, taking prescribed medications or suffer from any condition that may be affected by the suggested diet or fasting, please consult with your physician about how to proceed.

Day of the test

Patients should:

  • Brush their teeth two hours prior to taking the test
  • Bring their all prescribed medication to the test
  • Leave adequate time for their appointment
  • Be aware that the test may take up to three hours to complete
  • Bring reading materials to make themselves occupied during the test

FAQs: Patient preparation

What medications should patients stop taking before they undergo the test?

The following is a list of what medication to avoid before undergoing the test, otherwise there could be an impact on test results.

Time prior to test

Type of medication

4 Weeks


2 Weeks


72 hours


48 hours


24 hours

Proton pump inhibitors


How are studies performed on patients with diabetes?

Patients who are insulin dependent may not be able to observe an overnight fast in terms of glycaemic control. The general advice to those patients is to take half of their regular insulin dose after checking with their diabetes doctor to clarify any doubts they might have.

Most patients are aware of their own body condition and will sometimes carry glucose tablets with them if they feel that their blood sugar level is very minimal, but they should always be careful and pragmatic about their diet4.

Doctors are advised against giving 50g of glucose to a patient with diabetes; Lactulose is the preferred alternative. Sometimes, diabetics have slow gastric emptying preparing the patient to stay for a period of 3 to 4 hours might be useful in case an increase in gas levels is not observed.

Q: How does delayed gastric clearance affect the test?

If there is a delay in oro-caecal transit time, there may be no increase in gas levels within the set test period. Patients should be followed up with the following day to find out if they have developed any significant symptoms after the test as a guide to a possible positive test.


  • Saad, R. and Chey, W. (2014). Breath Testing for Small Intestinal Bacterial Overgrowth: Maximizing Test Accuracy. Clinical Gastroenterology and Hepatology, 12(12), pp.1964-1972.
  • Chang, L., Lembo, A. and Sultan, S. (2014). American Gastroenterological Association Institute Technical Review on the Pharmacological Management of Irritable Bowel Syndrome. Gastroenterology, 147(5), pp.1149-1172.e2.
  • Rana, S. and Malik, A. (2014). Hydrogen Breath Tests in Gastrointestinal Diseases. Indian Journal of Clinical Biochemistry, 29(4), pp.398-405.
  • Dr Anthony R. Hobson, PhD - British Society of Gastroenterology
  • Ledochowski M. H2-Atemteste. Innsbruck: Ledochowski; 2008.

About Bedfont ScientificBedfont® Scientific Ltd

Bedfont® Scientific has specialised in the design and manufacture of exhaled breath and gas monitoring instruments since 1976.

For medical gas monitoring, their Medi-Gas Check medical pipeline testing range verifies not only the quantity but also quality of gas administered to patients.

Bedfont's breath analysers include carbon monoxide (CO) monitors such as the Smokerlyzer®, used for smoking cessation, and the ToxCO®, used by emergency services, to diagnose CO poisoning.

The NObreath® FeNO monitor provides accurate analysis of airway inflammation for the control of asthma, and the Gastrolyzer® range aids in the detection of gastrointestinal disorders and food intolerances. Quick and non-invasive, breath analysis is the new blood test.

Sponsored Content Policy: publishes articles and related content that may be derived from sources where we have existing commercial relationships, provided such content adds value to the core editorial ethos of News-Medical.Net which is to educate and inform site visitors interested in medical research, science, medical devices and treatments.

Last updated: Feb 18, 2021 at 10:18 AM


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