Randomized Controlled Trial Demonstrating Cost‐Effective Method of Olfactory Training in Clinical Practice: Essential Oils at Uncontrolled Concentration

OBJECTIVES: Published data examining the efficacy of olfactory training (OT) has used standardized concentrations of odorants and the Sniffin’ Sticks testing method. Although well‐validated, these methods are costly and time‐intensive for the average otolaryngology practice. The purpose of our study was to evaluate the efficacy of using essential oils at random concentrations and the University of Pennsylvania Smell Test (UPSIT) for training and testing, and compare this with the existing data on OT. STUDY DESIGN: Randomized Clinical TrialMethods: Patients presenting to a tertiary care rhinology center with subjective loss of smell and olfactory loss measured by UPSIT were randomized to OT or control for 6 months. Only patients with loss of smell greater than one‐year duration, and loss associated with post‐infectious and idiopathic etiologies were included. Baseline UPSIT was compared to 6‐month UPSIT. An accepted 10% change or better was used to establish a significant improvement on UPSIT. RESULTS: 43 patients were enrolled. Eight patients were lost to follow‐up, with a total of 35 completing the study. Age ranged from 39–71 with an average of 56. Of 19 patients in the OT group, 6 showed significant improvement (32%), while only two out of 16 patients (13%) in the control group improved. Increasing age and duration of loss were significantly correlated to lack of improvement. CONCLUSION: Allowing patients to use random concentrations of essential oils to perform OT is as effective as published data using controlled concentrations of odorants for post‐infectious and idiopathic olfactory loss. LEVEL OF EVIDENCE: 1b.