Corticosteroids may restore sense of smell in COVID-19 patients

COVID-19 is known to cause loss of smell in certain patients. While this symptom is generally temporary, approximately 10% of patients may suffer from it for 6 months or more.

Earlier research carried out by a team of researchers from INRAE and ENVA observed that the SARS-CoV-2 infected olfactory mucosa is invaded by immune cells leading to its destruction and prolonged inflammation. Based on these observations, the same team decided to assess the effectiveness of corticosteroids--known for their anti-inflammatory properties-;in restoring the sense of smell.

Their results support the existence of a direct link between the loss of smell caused by the virus and a decrease in the olfactory neuron population in the nasal mucosa. In addition, they show that early treatment with dexamethasone, a commonly used corticosteroid, improves the recovery of olfactory abilities in animals.

The improvement of the olfactory capacities is associated with a reduction of the immunity cells in the mucosa, and an increased level of regeneration of the olfactory neuron population. These results suggest that the corticosteroid treatments currently used-;which have not been very successful in the treatment of prolonged anosmia-;could be more effective if prescribed early, at the onset of symptoms of loss of smell.