Last updated: 25 Oct 2026
Helicobacter pylori (H. pylori) is a common bacterium that can live in the lining of the stomach. Many people who carry it never have symptoms, but in others it causes gastritis (inflammation of the stomach lining) and stomach or duodenal ulcers, and long-term infection raises the risk of stomach cancer.[1][2] The urea breath test is one of the most common ways to check for it. This guide explains how the H. pylori breath test works, who may need it, what to tell your doctor beforehand and what the results mean.
What is H. pylori?
H. pylori infects the lining of the stomach and the first part of the small intestine. It is very common worldwide, and the US National Cancer Institute estimates that about two-thirds of the world's population carries it. Most people pick it up in childhood.[2] It is thought to spread through contact with saliva, vomit or stool from an infected person, and possibly through contaminated food or water.[1]
H. pylori is the most common cause of peptic ulcers, which are sores in the stomach or duodenum. It can also cause gastritis, which may last for life if not treated.[1] Studies show that treating the infection can lower the risk of stomach cancer in some groups, which is one reason doctors test for it.[2]
When might you need an H. pylori test?
Your doctor may suggest an H. pylori test if you have symptoms that could be due to gastritis or an ulcer, such as:[1][3]
- pain or a burning feeling in the upper tummy
- indigestion or heartburn that keeps coming back
- bloating, burping or feeling full soon after starting a meal
- nausea or loss of appetite.
Testing may also be advised if you've had a stomach or duodenal ulcer in the past, or to check that the infection has gone after treatment.[1][3] Because many conditions can cause these symptoms, your doctor may consider other tests at the same time.[1] Our article on stomach ulcers and H. pylori covers ulcers and their treatment in more detail.
How the urea breath test works
The urea breath test is based on a simple idea: H. pylori produces an enzyme that breaks down a substance called urea, releasing carbon dioxide that you then breathe out.[1][4]
In general, the test involves these steps:[1][4]
- A first breath sample. You breathe into a bag or tube to give a baseline sample.
- Swallowing the test substance. You swallow a tablet, capsule or drink containing urea that has been "labelled" with a special form of carbon.
- A second breath sample. After a short wait, you breathe into a second bag or tube.
- Comparing the samples. The two samples are analysed. If H. pylori is present, the labelled carbon shows up as carbon dioxide in the second sample.
The test is non-invasive, and MedlinePlus notes there is no known risk to having a breath test.[1]
What to know before your test
The accuracy of an H. pylori breath test can be affected by some medicines, including:[1][7]
- antibiotics
- acid-reducing medicines, such as proton pump inhibitors (PPIs)
- bismuth-containing medicines.
These can suppress the bacteria for a while and lead to a falsely negative result. Don't stop any prescribed medicine on your own. Tell your doctor about everything you take, including over-the-counter remedies, and follow the instructions you are given for your test. Instructions on eating, drinking and medicines before the test vary, so they are explained at your consultation. If you have questions before then, you can send them through our contact form.
Other ways to test for H. pylori
The breath test is not the only option. Your doctor will choose the test most suitable for your situation.[1][3][4]
| Test | What it involves | Notes |
|---|---|---|
| Urea breath test | Breathing into a bag or tube before and after swallowing a urea drink or tablet | Detects current infection; also used to check treatment has worked |
| Stool antigen test | Collecting a small stool sample | Detects current infection; also used after treatment |
| Blood antibody test | A blood sample | Can't tell a current infection from a past one, so it is less often used for diagnosis |
| Gastroscopy with biopsy | A thin, flexible camera passed through the mouth into the stomach, with small tissue samples taken | Used when the stomach lining needs to be seen directly, for example with warning symptoms |
A gastroscopy can also show ulcers, inflammation or other changes that a breath test cannot. To understand how this differs from a colonoscopy, see gastroscopy vs colonoscopy. For information on the endoscopy procedures offered at the clinic, see our Colonoscopy and Gastroscopy service page.
Note that the H. pylori breath test is different from the hydrogen breath test used to look for small intestinal bacterial overgrowth. Read about that in our article on the SIBO breath test.
Understanding your results
- Negative result: you probably don't have an H. pylori infection. If your symptoms continue, your doctor may look for other causes.[1]
- Positive result: you have an H. pylori infection. Treatment usually involves a combination of antibiotics together with a medicine that reduces stomach acid.[1][3][5]
Treatment works for most people, but not always. Your doctor may recommend a repeat test after treatment, often a breath or stool test, to make sure the infection has cleared. If it hasn't, a different combination of medicines may be needed.[1][3][5] It is important to take the full course exactly as prescribed.[5]
Symptoms that need urgent care
Seek urgent medical help
Go to the nearest Emergency Department or call 995 if you have:
- vomit with blood in it, or vomit that looks like coffee grounds
- black, sticky or tarry stools
- sudden, sharp or severe tummy pain that doesn't go away
- dizziness, fainting or a racing heartbeat.
These can be signs of a bleeding or perforated ulcer.[1][3]
See a doctor soon (not an emergency) if: you have indigestion with unexplained weight loss, difficulty or pain swallowing, repeated vomiting, a lump in your tummy, or tiredness that could be due to anaemia.[3][6]
Don't wait for a breath test if you have these symptoms. For black stools or other signs of bleeding, our article on blood in stool has more information.
Looking after your stomach
While you're waiting to be assessed, these general steps can help ease symptoms:[3][6]
- eat smaller meals, and avoid foods or drinks that trigger your symptoms, such as fatty or spicy food, coffee or chocolate
- avoid anti-inflammatory painkillers such as ibuprofen unless a doctor has advised them
- stop smoking and cut down on alcohol
- keep to a healthy weight.
If your symptoms include frequent heartburn, our GERD and acid reflux guide explains causes and management.
Frequently asked questions
What is the H. pylori breath test?
It is a test that checks for H. pylori infection in the stomach. You give a breath sample, swallow a tablet or drink containing labelled urea, then give a second breath sample. If the bacteria are present, the labelled carbon shows up in your breath.[1][4]
Is the urea breath test painful?
No. It is non-invasive and involves breathing into a bag or tube. MedlinePlus notes there is no known risk to having a breath test.[1]
Do I need to stop any medicines before an H. pylori test?
Some medicines, including antibiotics, acid-reducing medicines (such as PPIs) and bismuth, can affect the result. Don't stop any prescribed medicine on your own. Your doctor will tell you what to do before your test.[1][7]
What happens if my H. pylori test is positive?
Your doctor will usually prescribe a combination of antibiotics and an acid-reducing medicine. A repeat test may be recommended after treatment to check the infection has cleared.[1][3][5]
Is a breath test better than a blood test for H. pylori?
They answer different questions. A breath test shows whether you have an infection now. A blood antibody test can't tell a current infection from a past one, so it is less commonly used to diagnose infection.[1]
Is the H. pylori breath test the same as the SIBO breath test?
No. The H. pylori test uses labelled urea to look for a stomach infection, while the SIBO test measures gases produced by bacteria in the small intestine. They are separate tests.[1][4]
Sources
- MedlinePlus (US National Library of Medicine). Helicobacter pylori (H. pylori) Tests. https://medlineplus.gov/lab-tests/helicobacter-pylori-h-pylori-tests/
- National Cancer Institute. Helicobacter pylori (H. pylori) and Cancer. https://www.cancer.gov/about-cancer/causes-prevention/risk/infectious-agents/h-pylori-fact-sheet
- NHS. Stomach ulcer. https://www.nhs.uk/conditions/stomach-ulcer/
- National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Diagnosis of Peptic Ulcers (Stomach or Duodenal Ulcers). https://www.niddk.nih.gov/health-information/digestive-diseases/peptic-ulcers-stomach-ulcers/diagnosis
- NIDDK. Treatment for Peptic Ulcers (Stomach or Duodenal Ulcers). https://www.niddk.nih.gov/health-information/digestive-diseases/peptic-ulcers-stomach-ulcers/treatment
- NHS. Indigestion. https://www.nhs.uk/conditions/indigestion/
- MedlinePlus Medical Encyclopedia. Tests for H pylori. https://medlineplus.gov/ency/article/007501.htm
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