Cough-Variant Asthma: Pathobiology, Clinical Phenotyping, Diagnosis, and Evidence-Based Treatment Approaches

Objective: To evaluate current evidence on the pathobiology, clinical features, diagnostic approach, differential diagnosis, treatment, and prognosis of cough-variant asthma (CVA) within an integrated framework applicable to clinical practice. Methods: For this structured narrative review, PubMed/MEDLINE was searched from inception through September 1, 2026. Documents from the European Respiratory Society, CHEST, and the Global Initiative for Asthma, together with the reference lists of selected studies, were also reviewed. Priority was given to clinical guidelines, systematic reviews, prospective cohorts, diagnostic-accuracy studies, and randomized controlled trials. No formal risk-of-bias assessment or quantitative data synthesis was performed. Results: CVA is a biologically heterogeneous asthma phenotype in which cough is the sole or predominant manifestation. Normal baseline spirometry does not exclude the diagnosis. Diagnostic evaluation requires integrated interpretation of a compatible clinical pattern, objective evidence of variable expiratory airflow limitation or airway hyperresponsiveness, and reasonable exclusion of alternative causes. Fractional exhaled nitric oxide, blood eosinophil count, and induced-sputum eosinophilia may support the identification of type 2 inflammation but are not diagnostic in isolation. Inhaled corticosteroids are the cornerstone of treatment. When the response is inadequate, the diagnosis, inhaler technique, adherence, exposures, and comorbidities should be reassessed before treatment escalation. Direct CVA-specific evidence remains limited, particularly regarding pediatric patients, long-term prognosis, and treatment duration. Conclusion: The diagnosis of CVA should not be based on a single test, biomarker, or therapeutic response; clinical, physiological, and inflammatory findings should be evaluated collectively. Standardized diagnostic criteria and long-term randomized controlled trials are needed.