The recommended treatment for hyposmia (clinically reduced sense of smell) is olfactory training using odors in containers that the patients smell twice a day for several weeks. Adherence to the olfactory training regimen is, however, generally low. We aimed to investigate if a new form of olfactory delivery via scented nasal inserts could enhance olfactory training adherence by allowing participants to be mobile while performing the training and thereby lower perceived intrusion in their everyday life, using a randomized controlled parallel-group design. Two groups of individuals with hyposmia underwent 8 weeks of olfactory training. One group (n=60) performed olfactory training using scented nasal inserts (nasal plugs that retain nasal patency) and one group (n=56) performed the standard care regiment currently recommended by the Swedish healthcare system. We assessed objective and subjective olfactory ability before and after olfactory training as well as adherence to training. While both groups significantly improved their objective and subjective olfactory abilities, training with nasal insert produced similar improvement as standard care in overall treatment outcome. However, there was a significantly greater increase in discrimination performance and lower dropout rate (6.7%) in the nasal insert compared to the standard care group (23.2%). Critically, the nasal insert group had a significantly higher adherence to the training regimen, i.e. fewer missed training sessions. In addition, they reported overall greater satisfaction with their treatment. These data suggest that olfactory training with nasal inserts could serve as a more effective form of treatment for hyposmia, due to patients improved adherence to protocol and increased tendency to finish their treatment regimen.

JNL receives financial compensation from Sulcus Consulting AB where NosaMed AB, the maker of the NosaPlug, is a client.

NCT06142565

Funding was provided by grants awarded to JNL from the Knut and Alice Wallenberg Foundation (KAW 2018.0152), the Swedish Research Council (2021-06527), and a donation from Stiftelsen Bygg-Gota for Vetenskaplig forskning. The Nosa plugs were provided free of charged by Nosa Plug AB. The funders had no input on study design,

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