• For Healthcare Professionals
  • 17 Harley Street, London

What is the Hydrogen Breath Test? 

Hydrogen Breath Testing is a non-invasive diagnostic procedure used to detect various gastrointestinal disorders, particularly those related to carbohydrate malabsorption. The test we offer at UME Health can detect SIBO (small intestine bacterial overgrowth) but other tests can also detect irritable bowel syndrome (IBS) and lactose intolerance. During the test, patients consume a specific substrate and then breathe into a device at regular intervals to measure the levels of hydrogen and methane gases in their breath. 

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How does the Hydrogen Breath Test Work? 

Feelings of indigestion and bloating are often caused by a movement of gas including hydrogen moving through the digestive system. When carbohydrates are not properly absorbed in the small intestine, they reach the colon where bacteria ferment them, producing hydrogen and methane gases. These gases are then absorbed into the bloodstream and eventually exhaled through the lungs. By measuring the levels of these gases, healthcare providers can assess the extent of carbohydrate malabsorption and diagnose conditions such as bacterial overgrowth. 

What is the Hydrogen Breath Test used for? 

Hydrogen Breath Testing plays a crucial role in diagnosing gastrointestinal disorders, allowing healthcare providers to tailor treatment plans to individual patients' needs. By identifying specific carbohydrate intolerances or bacterial overgrowth, patients can make dietary adjustments and receive targeted therapies to alleviate their symptoms and improve their quality of life. 

What does a Hydrogen Breath Test look for? 

A hydrogen breath test is primarily used to diagnose gastrointestinal disorders related to carbohydrate malabsorption. The hydrogen breath test we provide looks out for hydrogen levels in the breath and SIBO. SIBO occurs when there is an overgrowth of bacteria in the small intestine, leading to symptoms similar to other gastrointestinal disorders, such as bloating, gas, diarrhoea, and abdominal pain. The bacteria ferment carbohydrates in the small intestine, producing hydrogen and other gases that can be detected in the breath. 

How do I prepare for the Hydrogen Breath Test? 

One month before:You’ll be asked to stop taking antibiotics or any antimicrobial treatment before undertaking the test. 

One week before: Please avoid probiotics, laxatives or fibre supplements. 

One day before: You’ll be asked to limit your diet to only low-fibre, easily digested foods.  

Foods to avoid: 

  • Bran, oats and wheat-based cereals 
  • Coarse breads (wholegrain, granary and soft grain varieties) 
  • Dairy products (i.e. milk, cheese, ice-cream, yoghurt and butter) 
  • Beans and high fibre vegetables and their skins (i.e. potatoes, lentils, peas, carrots, broccoli, cabbage and celery) 
  • Fresh and dried fruits 
  • Wholegrain breakfast cereals, nuts and seeds 
  • Starches except for boiled white rice (do not eat pasta or brown rice) 
  • Herbs and spices 
  • Food and drinks containing fructose 
  • Alcoholic beverages 

Foods you can eat: 

Chicken, fish, turkey, beef, lamb, pork, ham, eggs, tofu, black/green tea (non-herbal) and black coffee, plain boiled white rice, tomato (not skins), breads (white, low fibre and gluten-free), jelly and jam (no artificial sweeteners).


12 hours before the test: You must fast for at least 12 hours before, only drinking water during this time. You must maintain the fast for the whole duration of the test. 

On the day of the test:  You’ll also be asked to avoid exercising or sleeping within 1 hour before the test and for the whole duration of the test. Do not smoke (including e-cigarettes and vaping) on the day of the test. 

How does it work?


Self-Pay Options

We offer self-payment options, and we can provide you with a breakdown of the expenses linked to your treatment.


Fast Scans and Results

We offer exclusive consultations every day at our specialised diagnostic facility and results of scans will be reported and delivered within 2 days.


Local GP Available

In case you're in need of immediate private GP attention, UME Health provides expedited services for the same purpose.


Friendly and Welcoming Staff

At our clinic, we take pride in our friendly and welcoming staff. We want our patients to feel welcome and cared for.

Hydrogen Breath Test FAQs

Welcome to our FAQ section on cardiology! We understand that patients often have questions and concerns about their heart health, so we have carefully selected a range of commonly asked questions related to cardiology. Whether you're curious about symptoms, treatments, or preventive measures, this section below is designed to help you find comprehensive answers to your queries. Our aim is to provide valuable information and address any concerns you may have, empowering you to make informed decisions about your cardiovascular health. Explore the FAQ section below to find the answers you're looking for regarding all things cardiology.

UME Health Patients Reviews

At our clinic, we strive to provide the best possible care to our patients. We are dedicated to ensuring that each patient has a positive treatment experience and receives the best possible care from industry consultants. Our goal is to provide a comfortable and welcoming environment where our patients feel cared for and supported throughout their treatment journey. We value our patient's feedback and are committed to continuously improving our services to meet their needs.

Stephie Roberts
Stephie Roberts
I ran late and missed my appointment but the receptionist and nurse worked hard to ge me seen and the whole procedure was swift, professional and courteous.
Richard Thompson
Richard Thompson
I am very pleased to have found UME Health as after two agonizing weeks, I believe they have managed to relieve the pain to a certain extent. I am positive it will improve and await the next visit.
Sue Salter
Sue Salter
I was quite nervous of this health check but the whole team were kind professional and I left reassured and positive about my health
Ilhan Nebioglu
Ilhan Nebioglu
Was very happy at the Reception, especially with the care of Christine and very impressed by the Professor in the Stress cardio room, Professor Dr. Mrs Lee
Lisa Oosthuizen
Lisa Oosthuizen
Excellent,staff are friendly .Lisa & Vicky in radiology were very compassionate and caring.I'm grateful
Jono Mellows
Jono Mellows
Very efficient team on hand on my visit. Great job Jordan & Iris.
Larry Mc Grane
Larry Mc Grane
Great staff and amazing service overall.
Jinx Paul
Jinx Paul
Very convenient and reasonably quick simple process. The receptionists were extremely helpful and informative. Everyone I met was very respectful and the person performing the MRI scan was excellent at explaining everything and made sure I was comfortable.

We are here to help!

At UME Health, we are committed to providing exceptional healthcare services to our patients. Whether it's a question about your health, or you need assistance scheduling an appointment, don't hesitate to contact us - we are here for you!

UME Health is a leading outpatient and diagnostics centre located on Harley Street, offering high-quality imaging services and compassionate patient care.

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