Treatment of post‐viral olfactory dysfunction: an evidence‐based review with recommendations

Abstract

Background Post‐viral olfactory dysfunction (PVOD) is one of the most common causes of olfactory loss. Despite its prevalence, optimal treatment strategies remain unclear. This article provides a comprehensive review of PVOD treatment options and provides evidence‐based recommendations for their use. Methods A systematic review of the Medline, Embase, Cochrane, Web of Science, Scopus, and Google Scholar databases was completed according to the Preferred Reporting Items for Systematic Reviews and Meta‐Analyses (PRISMA) guidelines. Studies with defined olfactory outcomes of patients treated for PVOD following medical, surgical, acupuncture, or olfactory training interventions were included. The Clinical Practice Guideline Development Manual and Conference on Guideline Standardization (COGS) instrument recommendations were followed in accordance with a previously described, rigorous, iterative process to create an evidence‐based review with recommendations. Results From 552 initial candidate articles, 36 studies with data for 2183 patients with PVOD were ultimately included. The most common method to assess olfactory outcomes was Sniffin’ Sticks. Broad treatment categories included: olfactory training, systemic steroids, topical therapies, a variety of heterogeneous non‐steroidal oral medications, and acupuncture. Conclusion Based on the available evidence, olfactory training is a recommendation for the treatment of PVOD. The use of short‐term systemic and/or topical steroids is an option in select patients after careful consideration of potential risks of oral steroids. Though some pharmacological investigations offer promising preliminary results for systemic and topical medications alike, a paucity of high‐quality studies limits the ability to make meaningful evidence‐based recommendations for the use of these therapies for the treatment of PVOD.

Efficacy and safety of oral corticosteroids and olfactory training in the management of COVID-19-related loss of smell

“…Two recent articles by Miwa et al and Hura et al reviewed the literature on medical management for PVOD which included zinc, traditional Japanese medicine, alphalipoic acid, vitamin A, minocycline, theophylline, acupuncture, systemic and topical steroids, and OT [6,14]. Although none of these treatment options reached grade A evidence of efficacy, both reviews concluded that OT is the recommended approach.…”

“…Even a small proportion of affected patients may number in the tens of thousands in the case of COVID-19. Permanent olfactory loss may lead many to suffer from known comorbidities, such as depression and impaired cognition, and even maybe from earlier death [ 6 , 7 ].…”

Olfactory epithelium histopathological findings in long-term coronavirus disease 2019 related anosmia

“…A number of other topical agents have been investigated in small studies, but in a recent evidence-based review none were considered to provide sufficient evidence about which to make any treatment recommendations. 35 Given the large numbers of patients affected, this must be made a research priority.…”

Corticosteroid nasal spray for recovery of smell sensation in COVID-19 patients: A randomized controlled trial

“…Post-viral olfactory dysfunction is one of the most common causes of olfactory loss. Based on the available evidence, olfactory training is the recommendation for the treatment of post-viral olfactory dysfunction [ 8 ].…”