From the Guidelines
Olfactory training is the most established non-medication approach for treating anosmia, and it should be considered as the first line of treatment. This approach involves repeated exposure to four distinct scents (typically rose, eucalyptus, lemon, and clove) for 20 seconds each, twice daily for at least 3-6 months 1. The evidence suggests that olfactory training can be beneficial in improving olfaction, with 11 studies evaluating this intervention showing a benefit 1.
Treatment Options
In addition to olfactory training, other treatment options may be considered, including:
- Corticosteroids, particularly intranasal formulations like mometasone furoate, which may be beneficial in some cases, although the evidence is limited and inconclusive 1
- Insulin fast-dissolving film for intranasal delivery, which has shown promise in improving olfactory detection scores in post-COVID-19 patients with olfactory loss 1
- Theophylline, which may benefit some patients by increasing cAMP levels in olfactory neurons, although the evidence is limited 1
- Vitamin A drops, which may help regenerate olfactory epithelium in post-viral anosmia, including COVID-19 related cases, although the evidence is limited 1
Key Considerations
When selecting a treatment approach, it is essential to consider the underlying cause of anosmia, as different causes may require different optimal approaches. Early intervention generally yields better outcomes, and combining therapies, particularly olfactory training with appropriate medications, often provides the most comprehensive approach to anosmia treatment.
Limitations of Current Evidence
The current evidence for anosmia treatment is limited, with many studies having a high risk of bias or being of low quality. Further research is needed to fully understand the effectiveness of different treatment approaches and to develop more effective therapies for anosmia. However, based on the available evidence, olfactory training remains the most established and recommended treatment approach for anosmia 1.
From the Research
New Therapies for Anosmia
- Anosmia, the inability or decreased ability to smell, is estimated to afflict 3-20% of the population 2.
- Various studies have investigated potential treatments for anosmia, including acupuncture, olfactory training, and oral corticosteroids.
Acupuncture as a Treatment Option
- A controlled prospective study found that acupuncture was associated with a positive effect on odor discrimination in patients with postinfectious smell loss 3.
- A systematic review of existing literature on the use of acupuncture in treating olfactory dysfunction found that acupuncture may have a therapeutic effect on improvement of olfactory function across various types of olfactory disorders 4.
Olfactory Training and Oral Corticosteroids
- A pilot study investigated the efficacy and safety of oral corticosteroids and olfactory training as a treatment for patients with persistent olfactory dysfunction as a result of COVID-19, and found that the combination of oral corticosteroids and olfactory training may be beneficial in helping patients recover from olfactory loss 5.
- A review of the current literature regarding the management of post-COVID-19 olfactory dysfunction found that olfactory training should be initiated as soon as possible for patients with PCOD, and that patients may benefit from a limited intranasal or oral corticosteroid course 6.
Future Research Directions
- Further research is needed to investigate the efficacy of pharmacologic therapies for post-COVID-19 olfactory dysfunction, and to standardize outcome measures for assessing olfactory function 6, 4.
- Larger-scale studies are required to confirm the findings of existing studies and to establish the effectiveness of new therapies for anosmia 3, 5, 4.