Effective early strategy to prevent olfactory and gustatory dysfunction in COVID-19: a randomized controlled trial

Background. Olfactory and gustatory dysfunctions (OGDs) are key symptoms of coronavirus disease 2019 (COVID-19), which may lead to neurological complications, and lack of effective treatment. This may be because post-disease treatments may be too late to protect the olfactory and gustatory functions. Aim. To evaluate the effectiveness of early use of saline nasal irrigation (SNI), corticosteroid nasal spray, and saline or chlorhexidine gluconate mouthwash for preventing OGDs in COVID-19. Design. This study was a double-blind randomized controlled trial. Methods. The study was conducted from 5 May to 16 June 2022. We recruited patients from three hospitals who were admitted with COVID-19 but without OGDs on the day of admission. Olfactory and gustatory functions were evaluated using the Taste and Smell Survey and the numerical visual analog scale. Participants were randomized to the saline, drug or control groups. The control group received no intervention, saline group received SNI plus saline nasal spray and mouthwash, and the trial group received SNI plus budesonide nasal spray and chlorhexidine gluconate mouthwash. Participants were assessed again on the day of discharge. Results. A total of 379 patients completed the trial. The prevalence of OGDs was significantly lower in the saline (11.8%, 95% CI, 6.6-19.0%; P<0.001) and drug (8.3%, 95% CI, 4.1-14.8%; P<0.001) groups than in the control group (40.0%, 95% CI, 31.8-48.6%). Additionally, both interventions reduced the severity of OGDs. Conclusions. We demonstrated effective strategies for preventing COVID-19-related OGDs, and the findings may guide early management of severe acute respiratory disease coronavirus 2 (SARS-CoV-2) infection to reduce the incidence of COVID-19-related complications.