olfactory dysfunction and phantosmia in patients with covid-19 in northern iran

Background: one of the most common symptoms of covid-19 infection is olfactory dysfunction (od).objectives: this study aims to investigate od and phantosmia in covid-19 cases from northern iran.materials & methods: in this cross-sectional study, participants were 400 patients with covid-19 infection in rasht, iran from march 2019 to september 2020. all the patients were evaluated in terms of od and then followed up for 3 months face-to-face, by telephone call, or online.results: among 400 patients, 37.75% had od (19% hyposmia, 10.75% primary phantosmia, and 8% anosmia) during the initiation of the disease, but 121 (30.25%) including nearly 65% of anosmic and/or hyposmic cases reported phantosmia at different time intervals of followup visits. moreover, 65.38% of patients reported acute onset of od. the prevalence of od was significantly higher in patients aged <40 years (p=0.001) and in females (p=0.002). od improved in about 90% of patients within 3 months. peripheral oxygen saturation was better in anosmic cases and c-reactive protein level was higher in normosmic cases at their first visit. no significant difference was found in terms of other laboratory results.conclusion: od is a common complication of covid-19 infection, but seems not to be permanent. it is more common in young patients, females, and those with mild covid-19 infection.