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

Purpose: As the COVID-19 pandemic continues, an increasing number of patients are afflicted by olfactory loss, a now well-recognized symptom of the disease. Though many patients seem to recover their sense of smell after a few weeks, a certain proportion of them seem to develop long-lasting olfactory disorder. Yet, as of October 2020, there is no recommended standardized treatment to reduce the risk of developing long-term olfactory disorder. In this pilot study, we investigated the efficacy and the safety of oral corticosteroids and olfactory training as a treatment for patients with persistent olfactory dysfunction as a result of COVID-19.

Methods: Non-hospitalized patients with a sudden loss of smell and a confirmed COVID-19 diagnosis were recruited by hospital call from February to April 2020. These participants were submitted to an extensive psychophysical testing in order to identify those with persistent dysosmia. Dysosmic patients were then treated either by a 10-day course of oral corticosteroids combined with olfactory training, or by olfactory training alone. All participants were subject to a second olfactory test after a mean of 10 weeks.

Results: 72 subjects with documented COVID-19 infection performed the initial olfactory test, on average 5 weeks after losing their sense of smell. Amongst them, 27 (37.5%) patients showed persistent dysosmia and were all included in this study. Nine participants received oral corticosteroids and performed olfactory training (OCS + OT), while 18 performed olfactory training (OT) only. Only participants in the OCS + OT group had significantly improved their olfactory score and did so above the minimal clinically important difference for subjective improvement of smell (p = 0.007). Three of the participants who received oral corticosteroids reported minimal and transient side effects.

Conclusion: This pilot study may suggest the combination of a short course of oral corticosteroids and olfactory training is safe and may be beneficial in helping patients with enduring dysosmia recover from olfactory loss due to COVID-19. There is a crucial need for further investigation with larger cohorts to corroborate these findings.