For full details on how to prepare for your test download the patient flyer.


What can I eat before doing the test?

At least 24 hours before starting the test you will need to limit your diet to the foods listed below. For the last 12 hours before starting the test you will need to fast completely (no food or drink).

If you normally do not eat any of the foods on the list then you will need to fast for the full 24 hours before the test.

Foods you can eat on the limited diet are:

  • plain white bread (including gluten-free) – all forms of bread (baguettes, rolls etc.) and toast are allowed
  • plain white rice
  • plain white potatoes (no skin)
  • baked or grilled white meat or fish (no oily fish, no skin)
  • plain tofu
  • a maximum of two eggs
  • water
  • non-flavoured black coffee or
  • black tea (no milk, no herbal teas)
  • only salt may be used to flavour your food.
  • a little butter, oil or margarine is permitted (1tsp)

No other foods or drinks are allowed.

Milk and milk substitutes including oat, almond, rice and soya milks are not permitted.


Do I need to fast before the test?

You should fast for at least 12 hours before the test. Before fasting, you will also need to eat only a limited low-fermentable diet (see above) for at least 12 hours.


Once I start the test can I eat and drink?

You cannot eat during the test, but you can have small sips of water.


What if I make a mistake and eat food I’m not supposed to?

You should only eat the foods listed above on the day before the breath test. This is to make sure the bacteria in your gut are producing as little gas as possible when you start the test (to ensure your results are accurate).

If you eat something that is not on the list, you risk getting an invalid test result and you may have to pay for another breath test.


Do I need to stop or change medication before doing the test?

Some medications can affect the results of the test so you should avoid taking them before the test. These include:

Oral antibiotics Do not take for at least 4 weeks before the test
Laxatives & Pro-motility drugs (e.g. domperidone) – this also includes magnesium supplements Stop at least 1 week before the test
Probiotics (Bacterial supplements) Stop at least 1 week before the test
Anti-diarrhoea medication (e.g. Imodium) Stop at least 2 days before the test
Gaviscon Can interfere with the test process. Do not take from 24 hours before the start of the test until the test is complete.

If you require any of the above medications and feel unable to stop them for the required time, please consult the doctor that referred you for testing before doing the test. We are unable to provide specialist advice on how these medications may affect your results.

All other medications can be taken as normal, this includes:

  • Acid reflux medications (e.g. PPIs such as omeprazole, esomeprazole, lansoprazole, and H2A receptor antagonists such as famotidine, cimetidine)
  • Topical antibiotics (e.g. creams)
  • Antifungals
  • Vitamin & herbal supplements (except magnesium – see above)
  • Medications unrelated to gut health, such as statins, beta-blockers, anti-depressants, anti-histamines, inhalers, pain killers

Can I still do the test if I am unwell?

If you’re feeling unwell it is best to postpone the test until you are feeling better.



Are there any risks associated with this test?

There are no risks involved in performing your test, you may experience some of your usual digestive symptoms during the test, this is normal.


What does the test involve?

You will provide an initial breath sample by blowing into a test tube through a straw. This will give us your baseline reading.

Then, you will drink water containing a carbohydrate (lactulose, glucose, fructose or lactose) which needs to be drunk within a minute or two.

Breath samples then need to be taken at regular intervals over 2-4 hours (depending on which test you are doing), to monitor how your gut responds. Along with the samples, you will record any symptoms experienced using the symptom form provided, this helps your doctor to analyse your results.


What are the different kits?

We offer four different home breath tests for gut health. Lactulose and glucose tests can be used to help diagnose small intestinal bacterial overgrowth (SIBO). Lactose and fructose tests can be used to detect intolerances to milk sugars or fruit sugars respectively. You can find out more about each test in our ‘What Test’ section of the FAQs page.


What is included in the test kits?

The kit contains everything needed to do the test (just add water):

  • Test tubes (5 or 10 depending on test)
  • Straw
  • Substrate (lactulose, glucose, lactose or fructose depending on the test)
  • Labels
  • Symptom sheet
  • Instruction leaflet
  • Freepost envelope to post back for analysis

Inside the HMBT Kits


How long does the test take?

Collecting each sample will take less than a minute. You will need to collect several samples at specific times over a period of 2-4 hours. Read the instructions provided with your test carefully before starting.


Do I have to drink the substrate solution as part of my breath test?

Yes. Each kit contains a sugar substrate (whether your test contains lactulose, glucose, lactose, or fructose) that you should dilute in water and then drink at the correct point during the test. This is a very important step, failure to drink the whole sugar substrate diluted in a glass of water will make your test invalid.

Pouring Lactulose into Water


How do I collect a breath sample?

Your test will contain several collection tubes and a straw. For each sample, unscrew the lid and put one end of the straw in the collecting tube. Blow through the straw into the tube for 3-5 seconds until you see condensation forming on the inside of the tube. Immediately screw the lid back on (not too tightly). Watch our video for full instructions.


Can I take more than one breath test on the same day?

No. If you have been asked to take more than one test, e.g. lactose and fructose, you should do each test on a different day. You will need to follow the limited diet and 12 hour fast before each test. Taking two tests on the same day will produce invalid results.


How does the test work?

Breath tests for digestive health detect small amounts of hydrogen and methane gases in your breath. Our bodies cannot produce these gases themselves. Instead they are made by micro organisms living in our intestines, and the amount of hydrogen and methane they produce provides valuable insights into your gut health.

In SIBO, the extra bacteria in your small intestine are able to use the sugars that you eat before your body absorbs it. These bacteria, along with other micro organisms, convert the sugar into hydrogen and methane.

In food intolerances, the sugars you’re intolerant to don’t get absorbed efficiently by your body, so there is plenty available for the micro organisms that live in your large intestine to convert into hydrogen and methane.

A lot of the hydrogen and methane escapes your body as flatulence or belching but some is absorbed into your blood. The hydrogen and methane in your blood is released in your lungs and can be measured on your breath with a breath test.

Breath tests are a simple and safe way to collect these gases from your breath to start understanding your symptoms. This forms part of the information that a specialist doctor can use to help you to take better control of your gut health.


Is lactulose going to give me diarrhoea?

The Lactulose SIBO Breath Test contains lactulose, which is also sometimes used as a laxative. This test only uses a very small amount of lactulose and most people typically don’t experience any symptoms outside their normal range.

A small number of patients may experience diarrhoea, but this should be mild and short lived. If your symptoms persist, you should contact your referring doctor.


How long are the samples valid for?

The breath samples are stable for up to two weeks and across a wide temperature range (-20°C to 40°C). Samples received after two weeks of collection may be invalid.



When will I get my results?

Once the kit arrives back at our lab, the results will typically be available within 2-3 working days.


How will I get my results?

If you are a self-referred or private patient the results will be emailed to theyourself and/or the doctor that referred you or that we recommended to you. If you are an NHS patient, please contact the hospital that referred you for the results.


How is the test analysed?

The test is analysed by a state-of-the-art gas chromatography system, which measures hydrogen, methane, and carbon dioxide levels in line with recommendations by the UK and North American Consensus on Hydrogen and Methane-based Breath Testing.


Where is analysis done?

The breath tests are analysed by trained gas chromatography scientists in our laboratory in Cambridge, UK.


What is the difference between glucose and lactulose in the SIBO Breath Tests?

We provide two different tests that can help to diagnose small intestinal bacterial overgrowth (SIBO). Each test contains a different sugar substrate, either lactulose or glucose.

Lactulose tests are the most commonly used. Your body does not absorb lactulose so it can be used to detect SIBO at any point in your small intestine. But, because the lactulose is still present in your colon/large intestine, the test can sometimes give a positive result even if you don’t have SIBO.

Some people who get a positive result from Lactulose tests, may be asked to take a glucose test too. You may also be asked to take a glucose test if there are other reasons why a lactulose test may not work. Glucose is absorbed by your body in the first third of the small intestine, so it can only detect SIBO in that region. It will not detect SIBO if it is in lower parts of your digestive system. If you get a positive result from this test, then it is very likely that you do have SIBO.


I have more questions.

If you have questions that aren’t answered here, then please contact us: info@omedhealth.co.uk



What happens after I purchase a test?

All results are sent to the referring clinician within five working days of completion of your test who will arrange a time to speak through them with you.

If you a a self-referred patient the results will be sent to you within the same time period of five working days. You can then either take these to your GP to discuss an appropriate treamtent plan. If you prefer you can speak to a recommended consultant at an additional cost.


Will the App and Breath Analyser be compatible with any smart phone or tablet?

The Breath Analyser connects to the App via Bluetooth. The App is compatible with Apple devices running iOS v15.5 Safari up to latest version and with Android devices running v11 up to latest version.


How will I be able to get a test?

The App will be available to download from the iOS App and Play Store. We are in the final stages of bringing this and the device to you, but you can beat the queues by signing up to the waitlist now!


How will I know when to log entries using the App and Breath Analyser?

We understand that sometimes it is easy to forget to log your entries. Therefore, we have developed the App to remind you when to log and keep you updated with your progress throughout the day.  


How long does it take to log entries with the App and Breath Analyser?

Logging food, drink, symptoms and lifestyle via the app will be quick and easy and can be completed in a matter of seconds. In just over 30 seconds, you can complete one breath sample using the Breath Analyzer


Will I be able to use the App and Breath Analyser wherever I go?

Absolutely yes! It is crucial that our device and app slots into day-to-day life. The App will be on your mobile device so you can use this wherever your phone goes. The Breath Analyser is designed to fit seamlessly into your pocket or bag so you can use it anywhere, anytime, whether at home or on the go.



Lactulose – Small Intestinal Bacterial Overgrowth (SIBO) 

A lactulose breath test is used to diagnose SIBO, or Small Intestinal Bacterial Overgrowth. SIBO can cause symptoms like abdominal pain, bloating, and change your bowel habit, as it causes excessive fermentation by bacteria in your small intestine. This test can also see if you have excess methane in your gut, which can cause similar symptoms.  
We recommend a lactulose test to check for SIBO in most people. Lactulose is a non-digestible sugar so it passes through your whole gut. This means it can give us information about the bacteria in your large intestine as well as your small intestine.  


Glucose – Small Intestinal Bacterial Overgrowth (SIBO) 

Similar to a lactulose breath test, Glucose can also detect SIBO. This test can also see if you have excess methane in your gut, which can cause similar symptoms to SIBOHowever, glucose sugar is fully absorbed within the small bowel, so it can’t tell us about bacteria in your large bowelGlucose is recommended for patients with altered gut anatomy – for example people who have had weight loss surgery, or have had part of their small bowel surgically removed, as it reduces the risk of false positive results that could result from these surgeries, when using a lactulose HMBT



A lactose breath test is useful to diagnose lactose malabsorption or intolerance, which can cause abdominal symptoms in response to eating dairy products. Before doing a lactose test, we recommend you first take a Lactulose or Glucose SIBO test. The presence of SIBO can cause a false positive result for lactose malabsorption, so it’s important to rule this out with a SIBO test first. 



A fructose breath test is useful to diagnose fructose malabsorption or intolerance, which can cause abdominal symptoms in response to eating certain fruits. Before doing a fructose test, we recommend you first take a Lactulose or Glucose SIBO test. The presence of SIBO can cause a false positive result for fructose malabsorption, so it’s important to rule this out with a SIBO test first.


How do I purchase the test?

Currently breath testing kits for SIBO and food intolerances are only available to people in the UK, and can be purchased for £250.

To get your test, choose your test and complete the form. Please note, no payment is taken at this stage.

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