Background/aim: Allergic rhinitis (AR) is a respiratory disease caused by in ammation of the nasal mucosa. Intranasal corticosteroids (ICs) are an e ective treatment for AR; however, their use has been associated with atrophy in nasal mucosae. Because DNA damage has been linked to several chronic diseases, we hypothesize that use of ICs could cause DNA damage in nasal mucosa cells, leading to mucosal atrophy and septal perforation. Materials and methods: Sixty patients with moderate or severe AR were divided randomly into two groups. Mometasone furoate (MF) and antihistamine tablets (desloratadine) were given to the study (IC) group. Physiologic saline and desloratadine were given to the control ((serum physiologic (SP)) group. Nasal irrigation uid was taken from patients before study commencement and a er 4 weeks of treatment. e comet assay was applied to detect DNA damage in nasal mucosa cells. Results: Nineteen patients were excluded, leaving a study population of 41 patients (IC group: 17 patients; SP group: 24 patients). Genotoxic damage was evaluated by comet assay. Conclusion: Treatment with MF spray for 4 weeks does not cause DNA breaks within cells in the nasal mucosa. ese results could form the basis of clinical trials involving treatment with di erent ICs over longer treatment periods.