Study of Different Local Treatments of Post COVID-19 Smell Dysfunction.

Introduction: This study was designed to differentiate between the impact of the topical nasal spray of corticosteroids, antihistamines, a combination of them, and normal 0.2% saline in treating patients with post-coronavirus disease 2019 (COVID-19) smell dysfunction. Materials and Methods: Patients with hyposmia or anosmia (n = 240), who recently recovered from COVID-19, were enrolled in this trial and were randomly assigned to four parallel groups. Group I (G1) received a combination of topical corticosteroid and antihistamine nasal spray (n = 60). Group II (G2) received topical corticosteroid nasal spray (n = 60). Group III (G3) received antihistamine nasal spray (n = 60). Group IV (G4) received 0.2% normal nasal saline nasal spray (n = 60). The treatments were used in all groups for 3 weeks. The sense of smell was assessed using the butanol threshold and discrimination tests. The smell tests were evaluated weekly for 3 weeks. Results: The mean age of the patients was 51.9 ± 7.1 years; moreover, 83.8% and 16.2% were male and female, respectively. The results of the smell tests in the first week significantly improved with those in the third week (P< 0.001). The greatest degree of improvement was found in the first group, followed by the second, third, and fourth groups. Conclusions: The results suggest the ability of combination therapy of corticosteroid and antihistamine nasal spray to manage post-COVID-19 hyposmia or anosmia; however, this combination therapy was not superior to corticosteroid nasal spray. Trial registration ID: UMIN000043537.