How Are H. pylori and Autoimmune Gastritis Connected?
At a Glance
H. pylori is a common bacterial infection that can trigger or mask autoimmune gastritis (AIG) and significantly increase the risk of stomach cancer. Eradicating H. pylori is critical for lowering cancer risk, though it does not cure the underlying autoimmune damage of AIG.
In this answer
3 sections
Helicobacter pylori (or H. pylori) is a common bacterial infection that frequently coexists with autoimmune gastritis (AIG) [1]. While AIG is a condition where your immune system attacks your stomach cells, H. pylori is an external bacteria that infects the stomach lining. When you have both, H. pylori can trigger or worsen stomach inflammation, complicating your diagnosis and significantly increasing your risk for certain types of stomach cancer [1][2]. Eradicating an active H. pylori infection is a critical step in managing your health, though it requires careful follow-up with your gastroenterologist [3][4].
How H. pylori and Autoimmune Gastritis Overlap
It is very common for people to be diagnosed with H. pylori and AIG at the same time [5]. The relationship between the two is complex:
- Triggering the Immune System: Some research suggests that H. pylori might play a role in triggering autoimmune gastritis. The bacteria’s proteins can look similar to the cells lining your stomach. In a process called molecular mimicry, your immune system may get confused while fighting the bacteria and accidentally begin attacking your own stomach cells [6][7].
- Masking the Diagnosis: An active H. pylori infection causes intense, full-thickness inflammation in the stomach [1]. This intense inflammation can sometimes mimic or mask the early signs of evolving autoimmune gastritis, making it harder for pathologists to identify AIG on a biopsy [8][9].
Cancer Risks: Why H. pylori Matters for AIG Patients
When discussing stomach cancer risk in AIG, doctors monitor two different types of growths. H. pylori significantly worsens the risk for the more dangerous of the two:
- Gastric Neuroendocrine Tumors (gNETs): AIG inherently increases the risk of developing type 1 gNETs [10]. These are usually small, slow-growing tumors caused by high gastrin levels resulting from stomach cell damage [11][12].
- Gastric Adenocarcinoma: This is the more aggressive form of stomach cancer. While AIG itself carries an inherent risk for adenocarcinoma due to long-term stomach lining damage (atrophy), co-infection with H. pylori significantly amplifies and accelerates this danger [3][13]. H. pylori is a major pro-cancerous factor that contributes to cancer development by driving severe, chronic inflammation and damaging cellular DNA over time [2][14].
The Importance of Eradicating H. pylori
Because H. pylori aggressively accelerates stomach cancer risks, treating and eliminating the bacteria (a process called eradication) is highly recommended [3][4]. Eradication usually involves a 10-to-14-day regimen of multiple antibiotics combined with acid suppressants.
Once you finish the treatment, it is critical to ask your doctor for a test of cure (such as a breath test or stool antigen test) to confirm the bacteria is completely gone.
However, clearing the infection in AIG patients comes with unique nuances:
- Cancer Prevention: Clearing the bacteria removes the independent, aggressive inflammation that H. pylori creates [2].
- AIG Progression: In some cases, AIG can appear to rapidly progress or become “unmasked” after H. pylori is successfully treated [15][16]. This rarely means you will suddenly feel incredibly sick. Instead, this “unmasking” is something your doctor sees on a biopsy under a microscope. Clearing the bacterial inflammation simply leaves behind the underlying autoimmune damage, which becomes more obvious or continues its natural evolution [8][17].
Because of this, clearing the infection does not “cure” autoimmune gastritis, nor does it typically restore your body’s ability to absorb vitamin B12 if the parietal cells are already lost. You will still need ongoing surveillance, usually through routine endoscopies, to monitor your stomach lining for atrophic changes, gNETs, and gastric adenocarcinoma [13][18].
Common questions in this guide
Can an H. pylori infection cause autoimmune gastritis?
Why is it harder to diagnose autoimmune gastritis if I also have H. pylori?
Does having both H. pylori and autoimmune gastritis increase my cancer risk?
Will eradicating H. pylori cure my autoimmune gastritis?
How do I know if the H. pylori infection is completely gone?
Questions to Ask Your Doctor
Curated prompts to bring to your next appointment.
- 1.Which eradication therapy do you recommend for my H. pylori, and what side effects should I prepare for?
- 2.How long after finishing my antibiotics should I schedule a breath or stool test to confirm the bacteria is fully eradicated?
- 3.Did my biopsy show any signs of intestinal metaplasia or precancerous changes alongside the H. pylori and AIG?
- 4.How frequently will I need an endoscopy for cancer surveillance now that I have this dual diagnosis?
- 5.Will eradicating H. pylori change how we manage my B12 absorption or iron levels?
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References
References (18)
- 1
Features That Aid Identification of Autoimmune Gastritis in a Background of Active Helicobacter pylori Infection.
Choudhuri J, Hall S, Castrodad-Rodriguez CA, et al.
Archives of pathology & laboratory medicine 2021; (145(12)):1536-1543 doi:10.5858/arpa.2020-0615-OA.
PMID: 33635965 - 2
Host pathogen interactions in Helicobacter pylori related gastric cancer.
Chmiela M, Karwowska Z, Gonciarz W, et al.
World journal of gastroenterology 2017; (23(9)):1521-1540 doi:10.3748/wjg.v23.i9.1521.
PMID: 28321154 - 3
No H. pylori, no adenocarcinoma for patients with autoimmune gastritis.
Goldenring J
Gut 2023; (72(1)):1-2 doi:10.1136/gutjnl-2022-328068.
PMID: 35896359 - 4
Helicobacter pylori eradication for primary prevention of gastric cancer: progresses and challenges.
Liu Z, Xu H, You W, et al.
Journal of the National Cancer Center 2024; (4(4)):299-310 doi:10.1016/j.jncc.2024.06.006.
PMID: 39735441 - 5
Autoimmune Gastritis in Korean Patients with Gastric Tumors: Clinicopathologic Correlations and Diagnostic Histological Features.
Ahn S, Kim TS, Kushima R, et al.
Gut and liver 2025; (19(2)):177-188 doi:10.5009/gnl240223.
PMID: 39506312 - 6
Visiting Molecular Mimicry Once More: Pathogenicity, Virulence, and Autoimmunity.
Martins YC, Jurberg AD, Daniel-Ribeiro CT
Microorganisms 2023; (11(6)) doi:10.3390/microorganisms11061472.
PMID: 37374974 - 7
Potential contribution of Helicobacter pylori proteins in the pathogenesis of type 1 gastric neuroendocrine tumor and urticaria. In silico approach.
Sánchez Caraballo A, Guzmán Y, Sánchez J, et al.
PloS one 2023; (18(4)):e0281485 doi:10.1371/journal.pone.0281485.
PMID: 37098080 - 8
Helicobacter pylori Gastritis as an Initial Presentation of Evolving Autoimmune Gastritis: A Report of Two Cases.
Kotera T, Kushima R, Haruma K
Internal medicine (Tokyo, Japan) 2026; (65(6)):819-826 doi:10.2169/internalmedicine.5888-25.
PMID: 40769905 - 9
Autoimmune Gastritis and Helicobacter pylori Infection: Molecular Mechanisms of Relationship.
Bordin DS, Livzan MA, Mozgovoi SI, Gaus OV
International journal of molecular sciences 2025; (26(16)) doi:10.3390/ijms26167737.
PMID: 40869058 - 10
The changing face of chronic autoimmune atrophic gastritis: an updated comprehensive perspective.
Massironi S, Zilli A, Elvevi A, Invernizzi P
Autoimmunity reviews 2019; (18(3)):215-222 doi:10.1016/j.autrev.2018.08.011.
PMID: 30639639 - 11
Unmasking the high-risk phenotype in autoimmune gastritis: A pathologist's roadmap for the clinician.
Wang CL, Zeng M, Luo Y
World journal of gastroenterology 2025; (31(48)):115244 doi:10.3748/wjg.v31.i48.115244.
PMID: 41480315 - 12
Autoimmune metaplastic atrophic gastritis and association with neuroendocrine tumors of the stomach.
Nehme F, Rowe K, Palko W, et al.
Clinical journal of gastroenterology 2020; (13(3)):299-307 doi:10.1007/s12328-019-01074-7.
PMID: 31782113 - 13
ACG Clinical Guideline: Diagnosis and Management of Gastric Premalignant Conditions.
Morgan DR, Corral JE, Li D, et al.
The American journal of gastroenterology 2025; (120(4)):709-737 doi:10.14309/ajg.0000000000003350.
PMID: 40072510 - 14
Helicobacter pylori secretary Proteins-Induced oxidative stress and its role in NLRP3 inflammasome activation.
Kumar S, Dhiman M
Cellular immunology 2024; (399-400()):104811 doi:10.1016/j.cellimm.2024.104811.
PMID: 38518686 - 15
Rapid Progression of Autoimmune Gastritis after Helicobacter pylori Eradication Therapy.
Ihara T, Ihara N, Kushima R, Haruma K
Internal medicine (Tokyo, Japan) 2023; (62(11)):1603-1609 doi:10.2169/internalmedicine.0533-22.
PMID: 36261377 - 16
Rapid Development of a Hemorrhagic Hyperplastic Polyp in a Patient with Evolving Autoimmune Gastritis after Helicobacter pylori Eradication.
Kotera T, Takemoto T, Kushima R, Haruma K
Internal medicine (Tokyo, Japan) 2025; (64(16)):2446-2451 doi:10.2169/internalmedicine.4701-24.
PMID: 39924242 - 17
Enhanced activity of autoimmune gastritis following Helicobacter pylori eradication therapy.
Ihara T, Kushima R, Haruma K
Clinical journal of gastroenterology 2025; (18(2)):258-268 doi:10.1007/s12328-024-02092-w.
PMID: 39806234 - 18
Multimodal management of foregut neuroendocrine neoplasms.
Zhou Y, Li JW, Uedo N
Best practice & research. Clinical gastroenterology 2024; (68()):101889 doi:10.1016/j.bpg.2024.101889.
PMID: 38522885
This page explains the connection between H. pylori and autoimmune gastritis for educational purposes only. Always consult your gastroenterologist to discuss your specific diagnosis, biopsy results, and treatment plan.
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