Efficacy of Lactobacillus and Bifidobacterium in Allergic Rhinitis: A Narrative Review

Allergic rhinitis (AR) is a common chronic inflammatory condition of the nasal mucosa, driven by IgE-mediated immune responses to inhaled allergens. Despite the widespread use of antihistamines, steroids, and allergen immunotherapy, many patients continue to experience significant symptom burden, prompting interest in complementary therapies. Recent insights into the gut-lung axis and the immunoregulatory role of the intestinal microbiota have drawn attention to probiotics as a potential adjunct in AR management. This narrative review synthesizes current evidence on the therapeutic utility of two extensively studied probiotic genera, Lactobacillus and Bifidobacterium, in the context of AR. Preclinical studies in murine models have demonstrated that specific strains can attenuate allergic responses by modulating cytokine profiles, restoring the Th1/Th2 balance, enhancing regulatory T cell activity, and reducing serum IgE levels. Clinical data, though heterogeneous, suggest that selected strains may improve nasal symptoms and quality of life in both adult and pediatric populations. Meta-analyses support these findings, but they also highlight considerable variation in strain specificity, dosage, treatment duration, and patient characteristics across studies. The overall safety profile of these probiotics remains favorable, with minimal adverse effects reported. Although evidence supports a potential role for Lactobacillus and Bifidobacterium in AR management, inconsistencies and methodological limitations underline the need for more robust, strain-specific randomized controlled trials. Future research should focus on developing standardized protocols, defining clinical endpoints, and conducting mechanistic studies to elucidate their role in immunomodulation.