# Platelet-Rich Plasma for COVID-19-Related Olfactory Dysfunction: A Systematic Review and Meta-analysis of Randomized Controlled Trials

## TL;DR

This study reviews and analyzes randomized trials to assess if platelet-rich plasma (PRP) can help restore smell in people with long COVID.

## Contribution

A meta-analysis of RCTs evaluating PRP's effectiveness for treating olfactory dysfunction caused by COVID-19.

## Key findings

- PRP significantly improved objective and subjective olfactory scores in patients with long COVID.
- PRP increased response rates and was generally well-tolerated with minor side effects.
- The evidence is promising but limited due to a small number of trials and varying risk of bias.

## Abstract

A notable rise in olfactory dysfunction (OD) prevalence has been observed since the COVID-19 pandemic. COVID-19-related OD is associated with several consequences, especially deteriorated quality of life. Hence, several treatment options have been investigated, with platelet-rich plasma (PRP) showing promising results. A systematic review and meta-analysis summarizing randomized controlled trial (RCT) evidence were retrieved from PubMed, Google Scholar, Scopus, and Web of Science up to June 2025. The risk of bias was assessed using the Cochrane Risk of Bias 2 assessment tool. Data were analyzed using Stata MP version 18 (StataCorp LLC, College Station, TX), pooling dichotomous outcomes as relative risks (RRs) and continuous outcomes as standardized mean differences (SMDs), each with 95% confidence intervals (CIs). Four RCTs, including 198 participants, were included in our meta-analysis. PRP significantly improved objective olfactory scores (SMD = 1.86, 95% CI (0.14, 3.57), p = 0.03) and subjective olfactory scores (SMD = 0.92, 95% CI (0.32, 1.51), p < 0.001). Additionally, PRP significantly increased the response rate (RR = 1.79, 95% CI (1.14, 2.81), p = 0.01). PRP was generally well-tolerated across the included trials, with no major adverse events reported. Two RCTs showed an overall low risk of bias, one trial showed some concerns, and another showed a high risk of bias. With uncertain evidence, PRP may improve both objective and subjective smell function and clinical outcomes in people with long COVID-related OD. PRP treatment was reported to be safe, with minor, temporary side effects primarily related to the procedure. Although initial results are promising, the small number of RCTs requires a cautious approach to interpretation.