Intranasal Corticosteroid Short running head: Intranasal corticosteroid Type of manuscript: Review article

The introduction of intranasal corticosteroid (INS) has been the most important therapeutic progress in rhinitis management since the introduction of the first generation of antihistamines. Our knowledge of the mode of action of INS has improved as the airway mucous membrane of the nose is easily accessible for investigation. INS is highly effective in diseases characterized by eosinophil-dominated inflammation (allergic rhinitis, nasal polyposis, allergic fungal sinusitis) and in diseases characterized by neutrophil-dominated inflammation (acute and chronic rhinosinusitis). Experience for more than 30 years and a long series of controlled studies have shown that the treatment is highly effective and the side effects are few and benign. INS can therefore be considered as first-line treatment for allergic and non-allergic, non-infectious rhinitis, acute and chronic rhinosinusitis without and with nasal polyps.