Graphic of person breathing out molecules of hydrogen and methane

Digestive Health Tests

Take control of your digestive health through a simple at-home breath test.

I am a healthcare professional


Taking the guesswork out of digestive health

In total around 9 million people in the UK have some form of digestive illness. Digestive problems are a common source of discomfort for people worldwide, and they can really impact your daily life. It’s not always easy to work out what’s wrong if you’re suffering from regular bouts of bloating, cramps, flatulence, diarrhoea etc.

Specialists in gut health often use diagnostic tests, including hydrogen methane breath tests (HMBT), to diagnose disease and inform the most effective treatment options. By finding out what's wrong, you can start treatment or make changes to your diet that will make your life easier and mean you can start living more comfortably.

How do DIGESTIVE HEALTH breath tests work?    Digestive Health breath test FAQs


If you are affected by digestive health symptoms, you should first contact your doctor for a specialist referral. Our testing, in partnership with Functional Gut Diagnostics, is available in the UK either through the NHS or private healthcare, at a cost within NHS tarrifs.

Getting Tests

How can we help?

I live in the UK and I think I need a breath test

I’m a UK-based doctor and I’d like to refer patients for testing

You need to be referred for a breath test by a specialist doctor.

If you are not already under the care of a specialist, you should first consult your GP about your symptoms. If they agree that you may have gut health issues they will refer you to a specialist.

The specialist may decide you need several tests and some may require visits to hospital or a specialist clinic.

The gut health breath test service comes with specialist result interpretation and offers many benefits over in-house options. Tests are available in the UK for NHS (within the current NHS tarriff) or private healthcare.

To find out more visit the dedicated gut health page for healthcare professionals.

If you are a scientist or researcher and you'd like to find out how to add breath analysis into your gastrointestinal research please visit our research page.

Symptoms that may mean you need a digestive health breath test

  • Diarrhoea

  • Nausea

  • Bloating

  • Excess Gas

  • Abdominal Cramps

About the Test

What is a digestive health breath test?

FGD Owlstone Medical logosOwlstone Medical, the global leader in Breath Biopsy® for applications in early disease detection and precision medicine, has partnered with Functional Gut Diagnostics, leading providers of smart solutions for the diagnosis of gut health problems, to empower people with digestive health conditions and their doctors to take control of their symptoms through breath testing.

Visit Functional Gut Diagnostics

Doctors anywhere in the UK can refer patients for digestive health testing. If they think you have certain illnesses the tests may include a breath test which you can do yourself at home. The test will be sent to you in the post and consists of a test substance for you to mix with water and drink, as well as several tubes to collect your breath samples.

Breath tests can be used to help diagnose small intestinal bacterial overgrowth (SIBO) or food intolerances caused by lactose (milk) intolerance or fructose (fruit) intolerance.

Find out how it works

Digestive health breath test kit boxes

To ensure accurate results, you may need to do a few things, such as stop taking certain medications, for up to four weeks before doing your test. Full details of what to do and when are included in the flyers:

Doing the test is easy. You just blow through the straw provided into the collection tubes at the right times and write down any symptoms you’re experiencing. The whole test takes a little over two hours (SIBO) or three hours and twenty minutes (intolerances).

Once you’ve done your hydrogen methane breath test, post it back to us for analysis in our specialist lab. A trained clinical scientist will compile your test results into a report together with their expert commentary. The report will be sent to you and your doctor within a few days.

View FAQs

How to collect your samples.

Gut Breath Test Instructional Video

Possible Diagnoses

About SIBO and Food Intolerances

What is SIBO?

What are food intolerances?

Small intestinal bacterial overgrowth is when you have too many bacteria in your small intestine. Normally bacteria mostly live in the large intestine, too many bacteria in other parts of the gut can cause discomfort, diarrhoea, constipation and other symptoms.

 If you have digestive discomfort, or think you may have IBS, it could be SIBO and a breath test could help you find a diagnosis.

If your body is unable to correctly absorb certain foods then you may be intolerant to them. There are a few commonly recognised intolerances. Breath tests can be used to detect intolerances to simple sugars like lactose or fructose.

Blood tests for lactose malabsorption only detect certain genetic defects. Hydrogen methane breath tests can also detect secondary causes of illness.

How it Works

How does the digestive health breath 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. If you would like to learn more about the science behind digestive health breath testing this paper helps to explain the methods we use:

Read the paper      View the Case Study

Get Started

What can I do next?

Currently breath tests for SIBO and food intolerances are only available to people in the UK.

If you live in the UK, you will need to be referred by a specialist doctor. If you are not already under the care of a specialist, please contact your family doctor to discuss your symptoms and whether you should see a specialist.

I would like to refer patients for testing

If you're a specialist UK-based clinician please fill in the form on our dedicated page for healthcare professionals and we will be in touch.