Is Helicobacter useful for allergy?

Whether Helicobacter pylori (H. pylori) is beneficial for allergies is a debated topic. The hygiene hypothesis suggests that early-life exposure to H. pylori may reduce the risk of allergic diseases like asthma, hay fever, and atopic dermatitis by modulating regulatory T‑cell responses. Some cross-sectional and cohort studies support an inverse association, but the evidence is not consistent and does not prove causation. Importantly, H. pylori is a well-established pathogen causing peptic ulcers, chronic gastritis, and gastric adenocarcinoma. The provided context lacks direct data on H. pylori and allergy; thus the evidence level is 'mixed/unclear'. Recommending H. pylori infection for allergy prevention is not justified given its carcinogenic potential. Current allergy management should rely on allergen avoidance, antihistamines, and immunotherapy. If H. pylori is detected, medical evaluation is necessary – eradication is indicated for symptomatic or high-risk individuals. The potential allergy benefit is insufficient to outweigh the known risks.