What is H. pylori?
Helicobacter pylori uses the enzyme urease to break down urea into ammonia, neutralizing the acid around it so it can settle into the mucus layer of the stomach lining. Robin Warren and Barry Marshall first cultured and reported it in 1983, and they won the 2005 Nobel Prize in Physiology or Medicine for showing it causes gastritis and ulcers.
Infection and disease
It's mainly thought to spread within families in childhood, and most people who carry it have no symptoms. But long-standing infection causes chronic gastritis, and in some people it progresses through atrophic gastritis and intestinal metaplasia to stomach cancer (the Correa cascade). The WHO's International Agency for Research on Cancer classified it as a Group 1 carcinogen in 1994. It also causes duodenal and stomach ulcers and gastric MALT lymphoma.
How is H. pylori diagnosed and treated?
- Testing: urea breath test, endoscopic biopsy or rapid urease test, stool antigen test, and blood antibody test.
- Eradication therapy: an acid reducer plus two or three antibiotics for one to two weeks. Where clarithromycin resistance is common, alternatives such as bismuth quadruple therapy are used.
- Test of cure: confirm the bacteria are gone at least four weeks after finishing treatment.
Evidence for preventing stomach cancer
In a double-blind randomized controlled trial from Korea's National Cancer Center, treating infected people with a family history of stomach cancer cut cancer incidence over 9.2 years from 2.7% to 1.2% (HR 0.45). In patients who'd had early stomach cancer removed, it cut new cancers from 13.4% to 7.2% (HR 0.50). A meta-analysis in healthy carriers found a 34% lower risk. The absolute benefit is biggest in groups with high baseline risk.
This article is general health information and is not a substitute for diagnosis or treatment. If symptoms persist, see a doctor.
FAQ
- Should everyone be tested for H. pylori?
- In low-risk countries like the US, testing is usually recommended for people with ulcers, certain stomach symptoms, a family history of stomach cancer or other specific indications rather than everyone.
Sources reviewed: 2026-10-25
References
- Warren, J. R., & Marshall, B. (1983). Unidentified curved bacilli on gastric epithelium in active chronic gastritis. Lancet, 1(8336), 1273–1275.
- Choi, I. J., et al. (2020). Family history of gastric cancer and Helicobacter pylori treatment. New England Journal of Medicine, 382(5), 427–436.
- Malfertheiner, P., et al. (2022). Management of Helicobacter pylori infection: the Maastricht VI/Florence consensus report. Gut, 71, 1724–1762.