Effectiveness of Herbal Medicine Add-on Treatments for COVID-19: An Updated Systematic Review and Meta-analysis of Clinical Trials

Context: With the emergence of the COVID-19 pandemic, the use of traditional and herbal medicine as low-cost complementary treatment options was proposed. Despite supporting evidence on antiviral effects and previous experiences with such treatments, data on overall efficacy remain limited. This study aimed to assess the effectiveness of herbal medicine add-on treatments for COVID-19. Evidence Acquisition: A systematic review with meta-analysis of randomized controlled clinical trials (RCTs) was conducted to evaluate the effectiveness of herbal medicine add-on treatments for COVID-19. We searched PubMed, Scopus, Embase, Web of Knowledge, and Google Scholar for relevant articles from January 2019 to January 2024. Inclusion criteria were RCTs assessing herbal treatments for COVID-19; exclusions included non-RCTs and studies with unclear outcomes. Results: Fifty RCTs, comprising 6,031 subjects, were included in the meta-analysis. The results support the relative effectiveness of herbal medicine add-on treatments in improving certain outcomes among COVID-19 patients. These include reduced hospital length of stay (Los) [standardized mean difference (SMD): -0.60 days, 95% confidence interval (CI): -1.04, -0.16], shorter time for PCR tests to convert to negative (SMD: -0.56 days, 95% CI: -0.86, -0.23), reduced progression of disease to severe stages [risk ratio (RR): 0.47, 95% CI: 0.38, 0.58], decreased time to resolution of general recovery (SMD: -0.72 days, 95% CI: -1.17, -0.26), fever (SMD: -0.61 days, 95% CI: -0.93, -0.28), cough (SMD: -0.92 days, 95% CI: -1.69, -0.15), and dyspnea (SMD: -0.73 days, 95% CI: -1.22, -0.23). Conclusions: Although herbal medicine may improve some outcomes in COVID-19 patients, significant heterogeneities in available studies limit the ability to conclusively suggest effectiveness. More controlled placebo trials and conclusive evidence are needed to better understand the effects and guide clinical practice.