Association between combined allergic rhinitis and asthma syndrome in children and nitric oxide: mechanisms, clinical significance, and research progress.

Combined Allergic Rhinitis and Asthma Syndrome (CARAS) in children is a chronic airway inflammatory disorder with a high prevalence in childhood. In recent years, a growing body of studies has identified a close association between fractional exhaled nitric oxide (FeNO) and nasal exhaled nitric oxide (nNO) and the pathogenesis of CARAS in children. By synthesizing relevant literature retrieved from the PubMed database (1985-2025), this article provides an in-depth analysis of the roles of the NO/cyclic guanosine monophosphate (cGMP) signaling pathway, nitrosative stress, and organelle injury in the pathogenesis of CARAS in children. Meanwhile, it reviews the potential clinical significance of exhaled nitric oxide as a non-invasive biomarker in supporting the diagnosis and therapeutic monitoring of CARAS in children, analyzes the latest research advances and existing controversies, and outlines future research directions, thereby providing a theoretical basis for the optimized clinical management of this disease.