Breath tests
A breath test can help us determine a number of digestive conditions by assessing the levels of gases, such as hydrogen, methane, and carbon dioxide, that you breathe out. A rapid rise in exhaled hydrogen or methane may indicate bacterial overgrowth in your small intestine (SIBO). This test helps us evaluate your digestion in a non-invasive and simple way.
At Digestive Health UK, we offer private breath tests to ease your concerns and help us identify the cause of your symptoms. Book a consultation at either of our London clinics to see if you need a breath test.
How does a breath test work?
When sugar is digested, your small intestine releases gases such as hydrogen and methane, which eventually travel to the lungs and are exhaled.
To assess your digestion, we will measure the amount of hydrogen and methane you breathe out over 3 hours. This will occur after you drink a mixture of lactulose (a non-digestible sugar) and water.
The test will first involve giving a normal breath sample by breathing into a breathalyser machine. You will then need to take the lactulose sugar solution and give regular breath samples every 15 to 30 minutes across the 3 hours needed for the test. You may also be asked to record any symptoms you might experience during this process.
A H pylori infection can also be detected through a breath test. SIBO differs from H pylori bacteria, as H pylori is a foreign bacterium that should not be in the GI tract, whereas SIBO is the presence of existing gut bacteria in the wrong part of the bowels.
If we suspect you may have an H pylori infection, we can also assess the carbon dioxide levels in your exhaled breath to test for the presence of the bacteria. We will do this by having you give an initial breath sample, followed by you drinking a solution (containing urea) and breathing into a second bag.
If H pylori bacteria is present, it will break down the urea in the solution you drank, releasing more carbon dioxide into your breath. If the amount of carbon dioxide in your second sample is higher than your first sample, you have a positive test for the presence of H pylori.
How do I prepare?
Certain medications, foods, and activities can affect your breath test results, so you will need to follow these guidelines before your test.
One month before – You should stop taking any antibiotics. Please discuss stopping your course of medications with your doctor before taking action.
One week before – You should not undergo any test that requires your bowel to be cleansed, such as a colonoscopy or a barium enema. Don’t take any laxatives, stool softeners, stool bulking agents, any medication used to treat constipation, or probiotics.
One day before – You will need to follow a strict diet of low-fibre, easily digested foods beforehand. We will provide more detailed information about the diet you will need to follow before your appointment.
Do not eat anything from 6 pm onwards the day before the test. Water is allowed the night before the test.
The day of the test – Do not eat or drink in the morning. Refrain from eating, drinking, chewing gum, eating breath mints/sweets or smoking cigarettes (including e-cigarettes) before or during the test. Do not sleep or exercise during the test, as this can interfere with the result.
Hydrogen breath tests are considered very safe. In rare cases, the test sugar solution can cause loose stools. You may also find that drinking the test sugar solution triggers the usual symptoms of your existing condition.
Why might I need a breath test?
Excessive amounts of hydrogen, methane and carbon dioxide in your digestive system may indicate many digestive conditions. These include:
- Intolerance to specific sugars – this includes lactose, fructose, sucrose, or sorbitol. Lactose intolerance is the most common intolerance
- Small intestinal bacterial overgrowth (SIBO) – this is when there is an increase in the different types of bacteria in the small intestine, particularly if those that would normally grow somewhere else in the digestive tract
- H pylori infection
- Irritable bowel syndrome (IBS) – this test will help eliminate or identify underlying issues behind your condition
Test results
Your results may take a few days to receive from the lab, depending on what we find during our assessment. We will discuss your results and plan our next steps in a follow-up consultation. We can also email your results before the appointment if you would like to look before you visit our clinic. If you would prefer a virtual follow-up or phone call, we can accommodate this.
Our specialist will let you know whether you need a follow-up appointment and can send a letter summarising your results. We may recommend this if we have no concerns or unusual findings.
Book a private breath test
Breath tests can help us solve any issues that an imbalance in your digestion may cause. Our specialists may recommend one if you’re experiencing symptoms of gastrointestinal conditions, such as SIBO.
Contact our clinic if you are experiencing gastrointestinal issues. You will have a thorough consultation with one of our specialists to discuss your symptoms and medical history to determine the possible cause.