Treatments for Olfactory Dysfunction in COVID-19: A Systematic Review.

Introduction  Olfactory dysfunction (OD) has emerged as a notable symptom among coronavirus disease 2019 (COVID-19) patients, with its prevalence varying among different populations. Recognizing the need to provide therapeutic solutions for these individuals, the present study seeks to comprehensively review the current evidence on potential underlying mechanisms and treatment modalities to manage OD in COVID-19 patients. Objective  To review the recent evidence on treatments for OD in COVID-19. From the beginning of the study until August 2nd, 2023, we conducted a systematic search on four electronic databases, PubMed, Scopus, Embase, and Web of Science, to find relevant publications. Data Synthesis  In the present study, 37 articles were selected for data extraction and included in the final review. The total number of patients was of 3,560 (2,098 female and 1,462 male subjects). The predominant disorders reported were hyposmia, anosmia, and parosmia. In most of the studies, the pre and postintervention assessments were the same, except for one study, in which the pre-intervention assessment of the disorder was through the SST, Sniffin' Sticks Test (SST), and the post-intervention assessment was through the Visual Analog Scale (VAS) and the 22-item Sinonasal Outcome Test (SNOT-22). The findings suggest olfactory training (OT), ivermectin, palmitoylethanolamide, luteolin, and systemic corticosteroids, in combination with topical corticosteroids, are potential therapies for COVID-19 patients with olfactory impairment. Conclusion  Although the review suggested several medications for OD treatment, further research must delve into the specific impact of OT, a non-pharmacological modality, regarding the mitigation of OD. By continuing to investigate and refine these therapeutic approaches, we can better support COVID-19 patients and improve their quality of life while navigating the challenges posed by OD.