Intranasal Corticosteroid Treatment on Recovery of Long-Term Olfactory Dysfunction Due to COVID-19

Olfactory dysfunction is a recognized manifestation in patients infected with Coronavirus Disease 2019 (COVID-19). This investigation aimed to assess the effect of mometasone furoate intranasal spray on the improvement of smell dysfunction in post-COVID-19 patients.

This randomized placebo-controlled trial included 80 non-hospitalized adult patients who had persistent anosmia or severe microsmia for more than 4 weeks due to COVID-19 infection. The participants were randomly allocated to the intervention or placebo group to receive mometasone furoate nasal spray or sodium chloride intranasal spray during 4 weeks of follow-up, respectively. The patients' olfactory dysfunction was assessed in terms of visual analog scale (VAS), and smell test score according to the modified version of the University of Pennsylvania smell identification test for the Iranian population.

A total of 70 participants completed the follow-up period and were analyzed in this study. By comparing the olfactory scores including smell test and VAS scores, no significant differences were found between case and control groups at baseline, 2, and 4 weeks intervals. However, the change of both olfactory scores at pre to post-treatment intervals and 2-4 weeks was significantly higher in the mometasone group relative to the placebo group. At post-treatment, the frequency of anosmia was 22.9% reduced in the case group compared to the control group.

Overall, there was no significant difference in olfactory dysfunction between the two groups during follow-up. However, based on the significant between-group difference in terms of olfactory scores changes, it seems that the nasal corticosteroids may be a positive effect on the recovery process of patients who received more than 2 weeks.

2 Laryngoscope, 132:2209-2216, 2022.