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.
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54 sec · Captioned · H. pylori is a stomach cancer risk you can test for and treat with antibiotics.
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This page is for anyone who has heard that a common stomach germ, H. pylori, is linked to cancer. It explains what the germ is, which cancers it is tied to, and who gets tested.
The simple version
H. pylori is a bacterium that can live in the stomach. It is very common. NCI says about two-thirds of people worldwide 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.
NCI says H. pylori neutralizes the acid around it and burrows into the stomach lining. This lets it live there, sometimes for many years.
People often first pick up H. pylori during childhood. NCI says it spreads from person to person through oral contact with stool, saliva, or vomit.
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.
NCI describes long-term H. pylori infection as a risk factor for stomach cancer. 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. Treating the infection with antibiotics usually makes 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 also matters. 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. Ask your provider which test fits your situation.
Not everyone needs testing. NCI says most experts agree the evidence does not support widespread testing. The CDC recommends testing people who have:
- An active stomach or upper intestinal ulcer
- A history of ulcers
If you are found to have H. pylori, it can be treated. Treatment uses antibiotics. In one large trial, NCI reports, treatment cut stomach cancer cases by nearly 50% over 22 years. Ask your provider what applies to you.
What this means for you
If you have ongoing stomach symptoms, such as pain, see a doctor. If you have black stools, vomit blood, or have severe stomach pain, get care right away or call 911.
Your healthcare team can tell you whether testing makes sense for you, what any results mean, and whether treatment is right for your situation.
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.
- NCI says unnecessary treatment may be adding to H. pylori resistance to several antibiotics in the United States.
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.
- A test can find the infection.
- Antibiotics can treat it.
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.
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 can lead to certain stomach cancers in some people.
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. The CDC recommends testing people with ulcers or a history of ulcers. Your provider can advise you.
How is H. pylori treated?
It is treated with antibiotics. 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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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, and this 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 then compared with the sources listed on it, looking for statements those sources do not back up. That check is not a sentence-by-sentence record and can miss errors. 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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