Evaluating acupuncture as a therapeutic intervention for post-COVID-19 olfactory dysfunction: a systematic review and pilot study

Objective: Olfactory dysfunction (OD) is a common and persistent symptom of coronavirus disease 2019 (COVID-19) for which effective treatments remain limited. Acupuncture, widely used in Chinese medicine for olfactory disorders has uncertain efficacy in post-COVID-19 OD. Therefore, in this study, we aimed to explore the feasibility and preliminary efficacy of acupuncture in patients with post-COVID-19 OD. Methods: This study was a dual-phased study. Phase I involved a systematic review conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, encompassing eight databases. Phase II consisted of a pilot randomized controlled trial (RCT) enrolling 25 patients with moderate to severe post-COVID-19 OD. Participants were randomly assigned to receive either real (group A) or sham (group B) acupuncture. The intervention included eight sessions over 4 weeks, with assessments at baseline, post-cycle 1, 2-week washout, post-cycle-2 treatment, and 2-week follow-up. The primary outcome was the change in scores on the 12-item Assessment of Self-Reported Olfactory Functioning and Quality of Life (ASOF). Secondary outcomes included the short version of the Questionnaire of Olfactory Disorders-Negative Statements (sQOD-NS) and the traditional Chinese version of the University of Pennsylvania Smell Identification Test (UPSIT-TC). Results: The systematic review identified 22 studies (15 case reports, seven RCTs) suggesting that acupuncture may positively influence olfactory function. In the pilot RCT, no significant baseline differences were observed between groups. Group A showed steady improvement across all ASOF domains during Cycle 1 (SOC, mean = 5.86; SRP, mean = 3.26; ORQ, mean = 3.98), with slight declines during cycle 2 and 2-week follow-up, though scores remained above baseline. Post-cycle 1, group A showed higher mean SOC and ORQ scores compared with group B (7.00 vs. 4.67; 3.98 vs. 3.39). Improvements in secondary outcomes were also more pronounced in group A, whereas group B showed minimal changes. Conclusion: Acupuncture appears to be a safe and potentially effective treatment for post-COVID-19 OD, warranting validation through larger clinical trials.