The Effect of Corticosteroids on Post-Covid-19 Smell Loss: A Meta-Analysis

The rate of olfactory loss related to COVID-19 was reported between 4-89 percent. There is no approved treatment for patients who experience anosmia after the mentioned infection. This systematic review aimed to assess the therapeutic effects of corticosteroids on anosmia in COVID-19 patients.

Databases including PubMed, ISI Web of Sciences, Scopus, and Cochrane Library. Databases were searched up to September 2022 to find out randomized controlled trials that assessed the effect of corticosteroids on post-COVID anosmia/hyposmia. Only studies published in the English language were entered in this review.

Among the six relevant trials with a total population of 712, one study administered the combination therapy of both systemic and nasal corticosteroids, while others used intranasal corticosteroids. No significant difference was observed between the intervention (IG) and control (CG) groups in terms of duration of improvement from anosmia (mean difference:-1.799). The pooled effect of self-rating olfactory scores was assessed at 2 weeks and at the end point of the studies which revealed no significant effect in favor of the IG (pooled effect in 2 weeks: 0.739; in the endpoint: 1.32). The objective evaluation with different tools indicated that IG obtained higher scores at the endpoint of treatment. The pooled results showed that the number of patients who recovered from anosmia is higher in IG compared to CG (Odds Ratio: 1.719).

It appears that the duration of corticosteroid therapy more than two weeks may be a considerable effect on the recovery of smell dysfunction in COVID-19 patients.