Abstract
Allergic rhinitis (AR) and chronic rhinosinusitis (CRS) are chronic inflammatory disorders of the upper airways with rising global prevalence, contributing significantly to health and socioeconomic burdens. Conventional treatments-including glucocorticoids, antibiotics, antihistamines, and leukotriene inhibitors-remain insufficient in targeting the underlying pathophysiology. Bacterial lysates (BLs), functioning as immunomodulators, activate both innate, and adaptive immune pathways, reestablish Th1/Th2 equilibrium, lower immunoglobulin E concentrations, and attenuate Th2-mediated inflammation. Emerging evidence indicates that BLs (e.g. OM-85, Broncho-Vaxom) markedly improve total nasal symptom scores in AR, suppress Th2 cytokine (IL-4 and IL-13) secretion, and reduce recurrence rates and surgical interventions in CRS. In conjunction with standard therapies, BLs enhance mucosal immune defense and contribute to sustained clinical efficacy. Following the Scale for the Assessment of Narrative Review Articles guidelines, this review critically evaluates the composition, manufacturing processes, immunoregulatory mechanisms, and clinical progress of BLs in AR and CRS, providing a conceptual framework for their clinical application.