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June 2021BACKGROUND
Olfactory dysfunction affects approximately 15% of people and influences quality of life, psychiatric wellbeing, and safety (Laryngoscope. 2009;119:496-499; Laryngoscope. 2014;124:826-831). One of the most common causes of smell loss is persistent olfactory dysfunction after an upper respiratory illness (Laryngoscope. 2009;119:496-499). Over half of the patients who present with postinfectious smell loss (PISL) do not spontaneously improve, presumably due to virally mediated neuroepithelial damage (Laryngoscope. 2009;119:496-499; Laryngoscope. 2015;125:1763-1766). Although current therapies for smell loss are limited, olfactory training (OT) has shown promise, with improvement of olfactory function in select patients who undergo repeated exposures to various odors in a structured paradigm.
BEST PRACTICE
Existing evidence suggests that OT is a low-risk intervention that provides clinically relevant and sustained benefit in some PISL patients beyond the observed rates of spontaneous recovery. The majority of improvement is observed within the first few months of OT and is not dependent upon patient age. Earlier initiation of OT appears to offer greater benefit, and modifications to the training paradigm, including adding new odors or extending the duration of training, may offer some additional modest gains. Further research is required to determine the optimal OT parameters, to clarify the adjunctive potential of OT when paired with other proposed treatments for PISL (e.g., corticosteroids, vitamin B, acupuncture), and to identify the additive benefit of OT compared to spontaneous recovery over the long term.