Olfactory Training and Oral Corticosteroid Therapy for Persistent Postinfectious Hyposmia

Postinfectious hyposmia gained special attention in the postpandemic era, and persistent cases are particularly difficult to treat. Many unproven therapies are used in clinical practice, including corticosteroids, with insufficient evidence.

To establish the effectiveness of systemic corticosteroid therapy, associated with olfactory training, for persistent postinfectious hyposmia.

Patients with persistent postinfectious hyposmia were divided, based on comorbidities, into control group (submitted to olfactory training alone) and test group (associated 7-day course of prednisone 40 mg). Olfactory evaluations were performed (visual analogue scale, Alcohol Sniff Test, and Connecticut Olfactory Test), at baseline, and at the 3- and 6-month follow-ups.

There was no statistically significant difference between the test (n = 10) and control (n = 7) groups ( p  > 0.05) for primary outcomes (visual analogue scale, Alcohol Sniff Test, and Connecticut Olfactory Test), although there was statistically significant improvement of Alcohol Sniff Test scores in both groups at 6 months ( p  > 0.05). The study's statistical power was reduced due to the small sample size. Even without randomization, the groups were not comparable only in terms of age ( p  > 0.05). Although no statistically significant association was found, there was a clear tendency for improvement in the overall olfactory function, which may be spontaneous or due to olfactory training. No side effects were reported.

There was no statistically significant benefit of systemic corticosteroid therapy for patients with persistent postinfectious hyposmia ( p  > 0.05). Treatment with systemic corticosteroids should be individualized, and there is no consensus in the literature.