Background/objective: Sudden onset olfactory dysfunction is one of the specific symptoms of a viral infection of the upper respiratory tract, and especially for SARS-CoV2 (Haehner et al., 2020). Although most infected persons (75%) only experienced transient symptoms (Niklassen et al., 2021), around 5% are affected by persistent symptoms for up to more than one year (Tan et al., 2022). The focus of this study was to investigate whether olfactory training with concomitant medication using vitamin A nose drops or mometasone furoate nasal spray provides an additional benefit in the restoration of olfactory function and improvement of parosmia in patients with persistent olfactory dysfunction due to postinfectious aetiology.
Study Design: prospective intervention study
Materials and methods: Participants were 146 patients, age 20-83 years, with olfactory dysfunction (duration 1-48 months), all of whom performed “olfactory training (OT)” for 12 weeks. Fifty-two patients formed the OT control group, 52 additionally used vitamin A nasal drops in the “Kaiteki”-position and 42 were prescribed mometasone furoate nasal spray with a long applicator alongside with OT. Orthonasal olfactory function was determined by using “Sniffin’ Sticks”, retronasal function with “taste powders”. In addition, participants rated olfactory performance and nasal patency and filled in questionnaires pertaining the respective interventions.
Results: The analysis showed statistically significant improvements of all intervention groups in almost all investigated olfactory functions. However, the groups only showed differences for odor thresholds with patients in the vitamin A group exhibiting higher scores compared to the two other groups.
Conclusion: Over a 12-week intervention period vitamin A appeared to exhibit a benefit over mometasone furoate nasal spray or OT only.
Funding: This research received no external funding.