Infectious Disease · General Practice ·
Olfactory training improved post-COVID smell loss in a randomized trial
In a single-centre, assessor-blinded randomized trial, 70 adults with persistent post-COVID olfactory dysfunction were assigned to 12 weeks of olfactory training or no intervention. Training improved smell-test scores, with clinically relevant improvement reported in 57.9% versus 6.7% of participants, respectively.
- Randomized trial compared 12 weeks of training with no intervention.
- Clinically relevant improvement occurred in 57.9% versus 6.7%.
- No serious adverse events were reported.
- The primary smell score omitted threshold testing.
Olfactory dysfunction can persist after SARS-CoV-2 infection, but evidence for treatment is limited. This single-centre, randomized, controlled, assessor-blinded trial enrolled adults with at least three months of post-COVID smell loss and impaired identification testing. Participants were assigned to 12 weeks of olfactory training or no intervention. Of 70 randomized participants, 68 completed the randomized phase and were included in the per-protocol analysis (38 in the training group and 30 controls). The primary endpoint was change in a modified Sniffin’ Sticks score combining identification and discrimination; the threshold component was omitted because of testing-protocol limitations.
Scores improved more with training than with no intervention, with a significant time-by-group interaction (p<0.001). Protocol-defined clinically relevant improvement occurred in 22 of 38 participants receiving training (57.9%) and 2 of 30 controls (6.7%; p<0.001). Clinician-rated and patient-reported global improvement also favoured training. No serious adverse events were reported.
The findings support olfactory training as a potential option for adults with persistent post-COVID smell loss. Interpretation is limited by the single-centre design, the modest sample, per-protocol analysis, and use of a modified smell-test score that excluded threshold assessment. Improvements in the exploratory extension phase were reported after delayed training, but that phase does not replace the randomized comparison.
In practice
For adults with at least three months of post-COVID olfactory dysfunction and impaired smell identification, this single-centre randomized trial found greater improvement after 12 weeks of olfactory training than with no intervention. The result supports considering structured training as a treatment option, but does not establish broad effectiveness: only 68 participants were included in the per-protocol analysis, and the primary modified smell score omitted threshold testing. No serious adverse events occurred; further evidence would help confirm applicability across settings.
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BMC Medicine: Olfactory training for COVID-19–related smell loss: the smell trial ↗This is an automated AI-condensed summary that has not yet been reviewed by an editor. Always consult the full item at the original source.