Four-week use of oxymetazoline nasal spray (Nezeril) once daily at night induces rebound swelling and nasal hyperreactivity.

A randomized double-blind parallel study with 20 healthy volunteers was performed to examine the effect of oxymetazoline nasal spray on the development of rhinitis medicamentosa. For 30 days, 10 subjects were given oxymetazoline nasal spray once daily at night and placebo in the morning and at noon, while the others used oxymetazoline nasal spray three times daily. Before and after the course of treatment, the mucosal surface positions were determined with rhinostereometry, followed by histamine challenge tests. In the morning and the evening just before use of the nasal spray, symptoms of nasal stuffiness were evaluated on visual analogue scales (0-100). After 30 days, rebound swelling and nasal stuffiness were found in both groups. In the group receiving oxymetazoline nasal spray once daily at night, the mean rebound swelling was 0.8 mm (p < 0.01) and the estimated mean symptom score for nasal stuffiness in the evening was 43 (p < 0.05). In the group receiving the same nasal spray three times daily, the mean rebound swelling was 1.1 mm (p < 0.01) and the mean evening symptom score was 43 (p < 0.05). The finding of an increase in histamine sensitivity in both groups was taken to indicate nasal hyperreactivity. There was no significant difference in the investigated variables between the two groups. It is concluded that the risk of developing rebound swelling and nasal hyperreactivity remains, whether oxymetazoline nasal spray is used once or three times a day for 30 days.