The short answer
H. pylori is a common bacterium that can live in the stomach. Long-term infection can cause inflammation that may lead to certain stomach cancers and ulcers. It can be found with a test and treated with antibiotics, which can lower cancer risk in some people.
H. pylori is a common bacterium that lives in the stomach lining.
Long-term infection can cause inflammation that may lead to certain stomach cancers.
Most people with H. pylori never develop cancer.
The infection can be found with a test and treated with antibiotics.
Watch: The stomach bacterium linked to cancer
54 sec · Captioned · H. pylori is a stomach cancer risk you can test for and treat with antibiotics.
Educational only — this video explains general report language and is not medical advice. Only your care team can say what a result means for you.
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The full explanation.
The simple version
H. pylori is a bacterium that can live in the stomach. It is very common. Around the world, a large share of people carry it, often without knowing.
Most people with H. pylori never develop cancer. But long-term infection can cause inflammation that, over many years, may lead to certain stomach cancers.
The helpful news: H. pylori can be found with a test and treated with antibiotics.
What is H. pylori?
H. pylori is a spiral-shaped bacterium. It lives in the mucus layer that coats the inside of the stomach.
Most bacteria cannot survive the stomach's strong acid. H. pylori is special because it can protect itself from the acid and burrow into the stomach lining. This lets it live there, sometimes for many years.
People often first pick up H. pylori during childhood. It is thought to spread through contaminated food or water and through close contact.
How it can lead to cancer
Having H. pylori does not make you sick right away. But over time, the infection causes ongoing inflammation in the stomach lining.
Long-term inflammation can slowly damage the cells there. In some people, this damage leads to changes that may become cancer.
Because of this link, H. pylori is classified as a cause of stomach cancer by health experts. Still, it is important to remember that most people with H. pylori never get stomach cancer.
Which cancers are linked to it?
H. pylori is linked to two types of stomach cancer.
- Gastric adenocarcinoma: This is the most common type of stomach cancer. Long-term H. pylori infection raises the risk of this cancer.
- Gastric MALT lymphoma: This is a rare cancer of the stomach lining. Nearly all people with it show signs of H. pylori infection. In many cases, treating the infection can make these tumors shrink.
H. pylori can also cause stomach ulcers, which are painful sores in the stomach lining.
What raises the risk?
Not everyone with H. pylori faces the same risk. Several things can affect it.
Factors that may increase risk include:
- Certain strains of the bacterium that make a specific toxin
- Smoking, which raises stomach cancer risk in infected people
- A diet high in salt and processed meats
A family history of stomach cancer may also matter. These factors help explain why some people with H. pylori develop problems and most do not.
Testing and treatment
H. pylori can be found with a test. Different tests are available, including breath, stool, and blood tests, as well as tests done during a stomach exam.
Not everyone needs testing. Most experts do not recommend testing the general public. Testing is usually advised for people who have:
- A stomach or upper intestinal ulcer
- A history of ulcers
- Certain other stomach conditions, or after surgery for early stomach cancer
If you are found to have H. pylori, it can be treated. Treatment usually combines antibiotics with medicines that lower stomach acid. Clearing the infection can lower the risk of stomach cancer in certain people.
What this means for you
If you have stomach symptoms, such as ongoing pain, it is worth seeing a doctor. Simple tests can show whether H. pylori is present.
Your healthcare team can tell you whether testing makes sense for you, what any results mean, and whether treatment is right for your situation. They can also confirm that the infection is gone after treatment.
Why not test everyone?
You might wonder why doctors do not simply test every person for H. pylori. There are good reasons for a careful approach.
- The infection is very common, and most people with it never get cancer.
- Treating everyone would mean many people taking antibiotics who may not benefit.
- Overusing antibiotics can make them less effective over time, as bacteria become resistant.
For these reasons, experts focus testing on people who are more likely to benefit, such as those with ulcers. This targeted approach balances the benefits and risks of testing and treatment.
A calm way to think about it
Learning that a common bacterium is linked to cancer can be worrying. But context helps.
Keep in mind that:
- Most people with H. pylori never develop stomach cancer.
- Simple tests can find the infection.
- Antibiotics can clear it.
- Treatment can lower risk in the people most likely to benefit.
If you have stomach symptoms, or a family history of stomach cancer, it is reasonable to bring this up with your provider. They can decide whether testing fits your situation, guide any treatment, and help you understand what your results mean for your health.
Words to know
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Common questions
What is H. pylori?
H. pylori is a spiral-shaped bacterium that can live in the mucus layer of the stomach. It is very common worldwide and is often first picked up in childhood. Many people have it without knowing.
How does H. pylori raise cancer risk?
Long-term infection causes ongoing inflammation in the stomach lining. Over many years, this inflammation can damage cells and, in some people, lead to certain types of stomach cancer.
Which cancers are linked to H. pylori?
H. pylori is linked to a common type of stomach cancer called gastric adenocarcinoma and to a rare stomach lymphoma called gastric MALT lymphoma. It can also cause stomach ulcers.
Should everyone be tested for H. pylori?
No. Most experts do not recommend testing everyone. Testing is usually advised for people with stomach or duodenal ulcers, a history of ulcers, or certain other conditions. Your provider can advise you.
How is H. pylori treated?
It is usually treated with a combination of antibiotics and other medicines that reduce stomach acid. Treatment can clear the infection and, in some people, lower the risk of stomach cancer.
Does having H. pylori mean I will get cancer?
No. Most people with H. pylori never develop cancer. Other factors, such as the strain of bacteria, smoking, and diet, can affect the risk.
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Last updated: 2026-07-04Next planned review: 2027-07-04
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How this page was created
Cancer Explained does not originate medical claims. Every page restates guidance already published by the National Cancer Institute, the CDC, the USPSTF and the FDA, in plain language, with the source cited so you can check the original yourself. AI does the translating and organizing; automated checks test claims, citations, clarity and safety before anything publishes. We do not employ clinicians and do not intend to — our work is translation and navigation, not clinical judgment. Nothing here is personal medical advice, and no page can account for your particular situation.
Editorial status: Source checked — This page was written with AI assistance and checked line by line against the sources listed on it. That confirms the sources support what the page says. It is not a medical review, and it does not confirm the page is complete or right for your situation.
Human medical review: not completed. Pages here are not signed off by a clinician before they publish. That is not an oversight we are quietly working around: we restate published guidance and cite it, so the authority belongs to the source rather than to us, and every page names where its claims come from — you can verify us instead of trusting us. Where a volunteer clinician has reviewed a page, their name and credentials appear on it; where no name appears, no clinician has checked it. We are glad to have reviewers and are recruiting them, and we do not hold pages back waiting for one. Use this site to understand your situation and to ask better questions of the people treating you.
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