JAMA Otolaryngol Head Neck Srg

Stellate ganglion block fails to improve COVID-19–related parosmia

June 25, 2025

Stellate ganglion block isn't superior to placebo for the treatment of COVID-19–induced parosmia and shouldn't be recommended for this indication. The findings underscore the ongoing lack of effective, evidence-based interventions for this condition.

Study details: This single-center, randomized, double-blind, placebo-controlled trial enrolled 57 adults (aged 18–70) with persistent parosmia for at least 6 months following COVID-19 infection. Participants were randomized 2:1 to receive an ultrasound-guided stellate ganglion block (SGB) with 6–8 mL of 1% mepivacaine or saline placebo. The primary outcome was the proportion of responders at 3 months, defined as a ≥15-point decrease in the Parosmia Olfactory Dysfunction Outcomes Rating (DisODOR) score.

Results: Among 48 evaluable participants (32 SGB, 16 placebo), the 3-month response rate was 43% for SGB and 38% for placebo (difference, –5%; 95% confidence interval, –32% to 33%). No significant between-group differences were observed in clinical global impression of improvement. The time since COVID-19 infection and baseline characteristics were similar between groups.

Source:

Farrell NF, et al. (2025, June 12). JAMA Otolaryngol Head Neck Surg. Stellate Ganglion Block for the Treatment of COVID-19-Induced Parosmia: A Randomized Clinical Trial. https://pubmed.ncbi.nlm.nih.gov/40504522/