An international group of olfactory experts have recommended against the use of steroid treatments for loss of smell related to COVID-19. Instead, they recommend a natural remedy- smell training- due to its zero side effects and robust supporting base of evidence.
In the paper, the group of researchers and clinicans warned against the use of systemic corticosteroids, a treatment option that has been considered for loss of smell stemming from COVID-19. Their reasons included that evidence supporting their efficacy in treating the condition is weak, olfactory dysfunction often tends to heal spontaneously, and corticosteroids are known to have potentially adverse side effects.
While research has been limited investigating the use of steroid-based treatments to treat olfactory dysfunction from mild cases of COVID-19, existing research suggests that it may have little to no effect. One study, for example, involving 129 patients treated with topical or systemic corticosteroids, found the treatments had no influence on the prognosis of their olfactory recovery.
This comes even when considering another research paper with a study cohort of 27 patients which suggested slightly more positive results for steroid treatments. In the paper, patients who were treated for olfactory dysfunction via a mix of corticosteroids and smell training saw significant improvement in their sense of smell at a ten-week follow up compared to those who received only smell training. Questionable due to the small sample size, the researchers also cautioned that the results of this study could be skewed as the groups studied were not similar enough- there was a higher of patients in the smell training-only group, and thus a higher variance.
This doesn’t mean however that the group of olfactory experts recommended that systematic corticosteroids be completely abandoned for usage among COVID-19 patients. Indeed, they mentioned that current evidence supports their potential usefulness in more severe cases of COVID-19 where nasal inflammation is present at the time of clinical examination.
To treat olfactory dysfunction in milder cases of COVID-19 though, the experts recommended smell training, which involves sniffing at least four odours twice daily for several months, as a frontline treatment. This is supported by studies including a review article published in 2020, which recommended olfactory training to treat post-viral olfactory dysfunction from an analysis of 552 candidate articles and 36 relevant studies.