Helicobacter pylori: should you get tested even without symptoms?

Between 15 and 30% of people in France carry Helicobacter pylori in their stomach, and most of them have no idea. This bacterium is picked up in childhood and, without treatment, stays for life. It is associated with most ulcers and, according to France’s National Cancer Institute (INCa), with about 80% of stomach cancers. Should you look for it when you feel fine? In France, the National Authority for Health (HAS) does not plan screening for everyone. It does, however, list specific situations in which a test is justified, even without any digestive pain.

Helicobacter pylori: what kind of bacterium is it?

Helicobacter pylori is a spiral-shaped bacterium that lives only in the human stomach, clinging to its lining. Australians Barry Marshall and Robin Warren described it in patients with gastritis and ulcers (Marshall and Warren, 1984). Their discovery earned them the Nobel Prize in Medicine in 2005.

More than half of humanity carries this bacterium. A meta-analysis of 184 studies conducted in 62 countries estimated that 4.4 billion people were infected in 2015 (Hooi et al., 2017). Prevalence ranges from 18.9% in Switzerland to 87.7% in Nigeria.

In France, the HAS puts the prevalence of H. pylori at between 15 and 30%, and falling. It stays below 20% before age 30 and approaches 50% after 50-60, a gap that reflects the childhood hygiene of older generations. The bacterium spreads from person to person, most often within the family and before adulthood.

H. pylori infection now has its own entry in the International Classification of Diseases (ICD-11). The European Maastricht VI consensus draws a principle from this: every carrier should be offered treatment (Malfertheiner et al., 2022). That does not mean everyone should be tested: the decision depends on each person’s risk.

How Helicobacter pylori quietly damages the stomach

H. pylori always inflames the stomach lining, but this inflammation stays silent in the vast majority of carriers. To survive the acid, the bacterium produces an enzyme, urease, which generates ammonia around it. Some strains inject a protein called CagA into stomach cells and secrete a toxin, VacA, and both modulate the immune response (Kusters et al., 2006).

This constant assault sustains a chronic gastritis that can last a lifetime. Prolonged inflammation exposes the cells of the lining to repeated DNA damage, a mechanism detailed in our pillar page on genomic instability. The WHO’s International Agency for Research on Cancer classifies H. pylori as a definite human carcinogen (Group 1).

The consequences of a long-standing H. pylori infection go beyond ulcers:

• Ulcers: according to the HAS, 95% of duodenal ulcers and 70% of stomach ulcers are associated with H. pylori.
• Stomach cancer: 89% of gastric cancers located away from the junction with the esophagus are thought to be attributable to H. pylori, or about 780,000 cancers a year worldwide (Plummer et al., 2015).
• Gastric MALT lymphoma, a rare cancer of the stomach’s lymphoid tissue, which often goes into remission after eradication.
• Iron deficiency: carriers have a 1.72-fold higher risk of iron-deficiency anemia, according to a meta-analysis of 14 observational studies (Hudak et al., 2017). Our guide to low or high ferritin explains how to read this marker.
• Vitamin B12 deficiency: an atrophied lining secretes less acid and less intrinsic factor, two elements the body needs to absorb it.

The cancer risk follows a slow, step-by-step progression. The Kyoto consensus points out that this risk rises with the extent and severity of gastric atrophy (Sugano et al., 2015). Each stage takes years, which leaves a window for prevention.

Treating Helicobacter pylori without symptoms: what the trials show

In symptom-free carriers, eradicating Helicobacter pylori cuts the risk of stomach cancer by about half, according to trials conducted almost entirely in Asia. The most recent Cochrane review pooled 7 trials and 8,323 participants: treatment lowered the incidence of this cancer by 46% (RR 0.54) and its mortality by 39% (RR 0.61) (Ford et al., 2020). All-cause mortality did not change (RR 0.97).

The link first emerged in a Japanese cohort of 1,526 patients followed for 7.8 years. Stomach cancer developed in 2.9% of H. pylori carriers, compared with none of the 280 non-carriers (Uemura et al., 2001). This type of study shows an association, not the effect of a treatment.

The first large trial followed 1,630 healthy carriers in Fujian, China. After 7.5 years, the total number of cancers had not fallen (7 versus 11), but no cancer appeared in treated people who had no precancerous lesion at baseline, compared with 6 in the placebo group (Wong et al., 2004). After 26.5 years, the gap became clear: 2.57% of the treated group developed cancer versus 4.31% on placebo, a 43% lower risk (Yan et al., 2022).

In Linqu County, among 2,258 carriers of the bacterium, two weeks of treatment halved the risk of gastric cancer, with an effect still visible 22 years later (Li et al., 2019). A second trial there covered 980 villages and 180,284 residents. Over 11.8 years, the reduction was more modest: 14% in the intention-to-treat analysis, 19% when eradication succeeded (Pan et al., 2024).

Two Korean trials concern people at high risk. After endoscopic removal of a first early cancer, eradicating H. pylori lowered the risk of a second cancer from 13.4% to 7.2% over 5.9 years (Choi et al., 2018). Among 1,838 carriers with an affected parent, brother, sister or child, treatment reduced the risk by 55% over 9.2 years: 1.2% developed cancer versus 2.7% (Choi et al., 2020).

These figures have a limitation: six of the seven Cochrane trials were conducted in East Asia, where stomach cancer is far more common than in France. The authors warn that their results may not apply elsewhere. In these trials, 72 carriers had to be treated to prevent one cancer (Ford et al., 2020). An earlier analysis put this number between 15 for Chinese men and 245 for American women (Ford et al., 2014).

Who should get tested for Helicobacter pylori? The French benchmarks

In France, the decision to take a Helicobacter pylori test is made case by case, because gastric cancer remains uncommon there. The HAS and France’s national professional council of hepato-gastroenterology listed the indications in a guidance sheet published in 2017. Several of them concern people with no digestive symptoms at all. Unexplained anemia or vitamin B12 deficiency should also bring H. pylori to mind.

Family history is the most overlooked situation, according to the HAS itself. Having a parent, brother, sister or child with stomach cancer justifies looking for the bacterium, even when you feel well. France’s National Cancer Institute points out that the infection leads to cancer in fewer than 1% of cases, but that this risk climbs with family history, a point the US National Cancer Institute also makes.

International consensus statements go further for at-risk populations. The Taipei consensus recommends testing vulnerable people, such as relatives of patients, and reserves mass screening for regions where gastric cancer is common (Liou et al., 2020). Its 2025 update confirms this priority and stresses that Helicobacter pylori spreads mainly within families (Liou et al., 2025). As early as 2014, the WHO, through its International Agency for Research on Cancer, invited the hardest-hit countries to study such programs.

Aspirin calls for a nuance. In the United Kingdom, the HEAT trial tested 30,166 people aged 60 and over taking low-dose aspirin. Among the 5,352 carriers randomized, treatment cut hospitalizations for bleeding ulcers by 65% over 2.5 years, after which the effect disappeared (Hawkey et al., 2022). Testing everyone on aspirin is therefore not the rule.

Which test should you choose to detect Helicobacter pylori?

For a person without symptoms, the HAS advises serology, in other words a blood test, as the first step. A negative result rules out infection. A positive one normally leads to a gastroscopy with biopsies, which confirms the presence of H. pylori and looks for precancerous lesions. Antibodies persist for months, even years, after the infection is cured: serology is never used to check whether treatment worked.

The carbon-13 urea breath test is the most accurate of the tests that do not require endoscopy. A Cochrane review of 101 studies and 11,003 participants compared it with the other methods (Best et al., 2018). At an equal specificity of 90%, its sensitivity reaches 94%, versus 84% for serology and 83% for stool antigen tests. Out of 1,000 people tested, half of whom carry the bacterium, it would miss about 30 infections, compared with 86 for serology.

One precaution determines the reliability of every test other than serology. According to the HAS, proton pump inhibitors (PPIs), such as omeprazole, must be stopped at least 2 weeks before, and antibiotics at least 4 weeks before. Otherwise, the test may give a false negative. Never change a prescribed treatment without your doctor’s advice.

Positive test: next steps and precautions

A positive H. pylori test is not an emergency, but it calls for a full course of treatment followed by a check. The Kyoto consensus recommends offering eradication to every carrier unless there is a reason not to, and places the greatest benefit before any atrophy of the lining. This is the central argument for longevity: treating early shortens an inflammation that, left in place, wears down the lining and impairs the absorption of iron and vitamin B12.

• Review the situation with your doctor: depending on age and history, a gastroscopy may come before treatment to look for lesions and test antibiotic susceptibility.
• Take the full course of treatment. The HAS recommends a 10-day bismuth quadruple therapy, a 14-day “concomitant” therapy, or a 10-day triple therapy guided by antibiotic susceptibility testing.
• Expect side effects, which are usually mild. In the Korean trial in relatives, 53.0% of treated patients reported some, versus 19.1% on placebo.
• Check eradication at least 4 weeks after finishing the antibiotics, with a breath test or a stool antigen test. No treatment is 100% effective.
• Postpone treatment during pregnancy or breastfeeding, as the HAS specifies.
• Tell your relatives if there is a family history of stomach cancer, so they can talk to their own doctor.

Antibiotic resistance explains why the follow-up test matters. In Europe, a 2018 study in 18 countries found H. pylori strains resistant to clarithromycin in 21.4% of cases, and to metronidazole in 38.9% (Mégraud et al., 2021). In France, the HAS reported 22% clarithromycin resistance in 2014, versus 14% in 1997. The choice of drugs is therefore a job for the doctor, never for leftover antibiotics.

Treatment also has its limits. In the Matsu Islands, mass screening brought Helicobacter pylori prevalence down from 64.2% to 15.0%, with reinfection below 1% a year (Chiang et al., 2021). Inflammation of the esophagus appeared there in 6% of those treated (Lee et al., 2013). The 2025 Taipei consensus finds that eradication does not raise the risk of reflux-related esophageal cancer, but calls for research into its lasting effects on the gut microbiome.

Frequently asked questions about Helicobacter pylori

Should you get tested for Helicobacter pylori without any symptoms?

Not routinely in France, where there is no screening program for the whole population. The HAS does, however, advise a test without symptoms when a parent, brother, sister or child has had stomach cancer. The same applies after an ulcer with no proof of eradication, before obesity surgery, or in the case of unexplained iron-deficiency anemia or vitamin B12 deficiency.

What is the most reliable test to detect Helicobacter pylori?

The labeled urea breath test is the most accurate of the tests that do not require endoscopy, with a sensitivity of 94% in the 2018 Cochrane review. The HAS nevertheless advises serology as the first step for a person without symptoms. A positive serology leads to a gastroscopy with biopsies, which also looks for any precancerous lesions of the stomach.

How do you catch Helicobacter pylori?

H. pylori passes from person to person, mainly in childhood and within the family. Once established, the bacterium persists for life without treatment. In France, the HAS estimates that 15 to 30% of the population carries it, with a prevalence close to 50% after age 50-60, linked to the hygiene conditions of past decades.

Does Helicobacter pylori always cause stomach cancer?

No. The vast majority of carriers will never develop cancer. The HAS estimates that about one infected person in 100 develops gastric adenocarcinoma after several decades. The risk rises with atrophy of the lining, family history and smoking. Eradication cuts this risk by 46% in trials conducted mainly in Asia, with a clearer benefit before lesions appear.

How long does H. pylori treatment last?

Treatment combines an acid-reducing drug with several antibiotics, for 10 or 14 days depending on the regimen chosen by the doctor. It must be taken in full, even with mild side effects such as an altered sense of taste. A breath test is then mandatory to confirm eradication, at least 4 weeks after the last antibiotic dose and 2 weeks after stopping PPIs.

Can you be reinfected with H. pylori after treatment?

It is rare in adults. In the Matsu Islands, Taiwan, where the adult population was screened and treated on a large scale, reinfection stayed below 1% a year. With such a low rate, a positive test shortly after treatment most often signals a failed eradication. The doctor then proposes another antibiotic regimen, ideally guided by susceptibility testing.