Interventions for the treatment of persistent post-COVID-19 olfactory dysfunction.

Area of Science:

• Otolaryngology
• Infectious Diseases
• Clinical Pharmacology

Background:

• Persistent olfactory dysfunction is a common and impactful consequence of COVID-19.
• Limited guidance exists for managing post-COVID-19 smell disorders.
• Interventions like medication and olfactory training have been suggested but their efficacy is uncertain.

Purpose of the Study:

• To evaluate the benefits and harms of interventions versus no treatment for persistent COVID-19-related olfactory dysfunction.
• To maintain an up-to-date evidence base through a living systematic review approach.

Main Methods:

• Included randomized controlled trials (RCTs) of interventions for COVID-19-related olfactory disturbance lasting at least four weeks.
• Compared interventions against no treatment or placebo.
• Primary outcomes included smell recovery, quality of life, and adverse effects; secondary outcomes included parosmia prevalence.

Main Results:

• Two small RCTs (30 participants total) evaluated systemic corticosteroids with intranasal treatments and palmitoylethanolamide plus luteolin.
• Both studies reported very low certainty of evidence for all outcomes.
• Meaningful conclusions could not be drawn due to small sample sizes and study limitations.

Conclusions:

• Very limited evidence exists on the efficacy and harms of treatments for persistent post-COVID-19 olfactory dysfunction.
• Ongoing trials are identified, and this living systematic review will be updated as new data emerge.