Your consultant may refer you for a Hydrogen and Methane Breath Test with us at The Functional Gut Clinic if they suspect that you may have small intestinal bacterial overgrowth, lactose intolerance or fructose intolerance. These conditions can cause a range of symptoms such as bloating, abdominal pain or nausea. A hydrogen methane breath test is a non-invasive test which can aid your consultant in diagnosing the above conditions, and therefore allow them to formulate a treatment plan to alleviate your symptoms. 

Your consultant can write a referral letter to us at the Functional Gut Clinic, 22 Upper Wimpole Street, London, W1G 6NB.

If you have any queries or questions then please email us at

How do I refer a patient?

To refer a patient for a Hydrogen & Methane Breath Test please complete our Physiology Request Form and return it to The Functional Gut Clinic; via email ( or fax (0207 224 1486).

The referral should include any relevant clinical information that may be useful to the physiologists who will be performing the test as well as clearly identify which test(s) are required.

Does the patient need to travel to London?

Patient's for hydrogen methane breath testing can either attend the Functional Gut Clinic, 22 Upper Wimpole Street, London, W1G 6NB or can perform the test at home via a postal breath test kit. Full instructions on how to perform the home test will be provided and telephone support given. A video showing how we do a breath test can been seen below. 

How do I get my results? 

Results are emailed, faxed or posted to both the referring consultant/GP and the patient. 

Emma Visits The Function Gut Clinic for a Hydrogen Breath Test.

Watch this short video below that shows what patients can expect from a visit to the clinic.