From the Guidelines
For post-viral anosmia following an upper respiratory tract infection 6 weeks ago, intranasal corticosteroids are the recommended first-line treatment, with mometasone spray (option c) being the most appropriate choice. The recommended regimen is typically one or two sprays in each nostril once daily for at least 6-8 weeks. Mometasone helps reduce inflammation in the nasal passages and olfactory epithelium, which may facilitate recovery of smell function, as supported by a study on postinfectious olfactory dysfunction 1. Oral steroids, while potentially effective, carry more systemic side effects and are generally reserved for cases that don't respond to intranasal treatment, as seen in studies on the management of post-COVID-19 symptoms 1. Decongestants are not recommended as they can cause rebound congestion with prolonged use and don't address the underlying inflammatory process affecting the olfactory neurons, as discussed in the European position paper on rhinosinusitis and nasal polyps 2020 2. Fluticasone drops are not commonly used for this condition. Patients should be advised that recovery of smell may be gradual and can take several months, with some cases benefiting from olfactory training (repeatedly smelling different essential oils daily) as an adjunctive therapy to help stimulate olfactory nerve regeneration. Key points to consider in the management of post-viral anosmia include:
- The use of intranasal corticosteroids as the first-line treatment
- The potential benefits of olfactory training as an adjunctive therapy
- The limited role of oral steroids and decongestants in the treatment of post-viral anosmia
- The importance of patient education on the potential for gradual recovery of smell and the need for prolonged treatment.
From the Research
Treatment Options for Post-Viral Anosmia
- Decongestants: There is no direct evidence to support the use of decongestants in treating post-viral anosmia 3, 4, 5, 6, 7.
- Oral steroids: One study found that a 15-day course of oral steroids combined with nasal irrigation may improve olfactory function, but the evidence is very uncertain 4.
- Mometasone spray: A randomized, double-blind clinical trial found that mometasone furoate nasal spray in combination with olfactory training showed a higher improvement in severe chronic anosmia by COVID-19 compared to olfactory training alone 6.
- Fluticasone drops: There is no direct evidence to support the use of fluticasone drops in treating post-viral anosmia 3, 4, 5, 6, 7.
Olfactory Training
- Olfactory training is considered a promising treatment option for post-viral anosmia, and may be used in combination with other treatments such as mometasone furoate nasal spray 4, 5, 6.
Diagnosis and Pathophysiology
- Post-viral anosmia usually occurs after an upper respiratory tract infection (URTI) and can be diagnosed based on history, clinical examination, and olfactory testing 3, 5.
- The exact location of the damage in post-URTI anosmia is not yet known, but direct damage to the olfactory receptor cells is likely, and central mechanisms cannot be completely ruled out 3.