The Post–COVID Sinonasal Spectrum: Allergic Rhinitis at the Homoeopathic–Surgical Interface: A Narrative Review of Aetiology, Clinical Features, Differential Diagnosis, Diagnostic Evaluation and Individualized Therapeutics "From SARS-Cov-2 Sequelae to Sinonasal Health: Integrating Inflammatory Phenotypes, Structural Assessment, Surgical Perspectives and Individualized Homoeopathic Therapeutics."

The sinonasal tract represents an important interface between environmental exposure, mucosal immunity, respiratory infection, olfaction, and upper-airway function. Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), introduced a distinct spectrum of post-infectious sinonasal manifestations, most prominently olfactory dysfunction, nasal symptoms, and persistent upper-airway complaints. However, the relationship between SARS-CoV-2 infection and subsequent allergic rhinitis remains incompletely established and should not be interpreted as a direct causal association in every patient. The persistence or emergence of rhinitis-like symptoms following COVID-19 therefore requires careful clinical phenotyping and exclusion of structural, inflammatory, infectious, medication-related, and other sinonasal disorders. This narrative review examines the post-COVID sinonasal spectrum with particular emphasis on allergic rhinitis and its position at the interface between homoeopathic clinical individualization and surgical/otorhinolaryngological assessment. The review discusses relevant aetiological and pathophysiological considerations, clinical manifestations, post-COVID olfactory disturbances, differential diagnosis—including deviated nasal septum, inferior turbinate hypertrophy, nasal polyps, chronic rhinosinusitis, rhinitis medicamentosa, non-allergic rhinitis and other structural or neoplastic conditions—and appropriate diagnostic evaluation. Particular attention is given to history-taking, anterior rhinoscopy, nasal endoscopy, allergy testing, olfactory assessment and the selective role of computed tomography. The therapeutic section presents a framework for individualized Homoeopathic Materia Medica consideration, emphasizing symptom totality, characteristic modalities, constitutional features and longitudinal assessment. Nevertheless, current evidence for homoeopathy in allergic rhinitis remains limited and heterogeneous, and it should not substitute for evidence-based medical therapy, diagnostic evaluation, or indicated surgical intervention. An integrated model is therefore proposed in which individualized complementary care is positioned alongside appropriate conventional management and timely specialist referral.