Herbal Medicine Treatment for Influenza: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

The aim of this research is to evaluate the clinical evidence of an herbal medicine (HM) treatment on influenza and describe the potential benefits and adverse events by reviewing all relevant randomized controlled trials. All papers published from 2010 to 2019 in all languages in six databases were searched, including all randomized controlled trials on adults and children, testing herbal medicine for treatment of influenza, alone or in combination with conventional antiviral therapy. The main outcome parameters of interest were total effective rate, time to resolution of fever, adverse events, complications, and duration of viral shedding. 25 trials of 3044 patients were included. Herbal medicine compared to placebo significantly reduced time to fever resolution by 4.96h (mean difference, -4.96; 95% CI, -7.11 to -2.80; P<0.00001), herbal medicine compared to oseltamivir showed no significant difference (mean difference, -1.82; 95% CI, -6.08 to 2.44; P=0.40), and herbal medicine plus oseltamivir combined treatment significantly reduced duration of fever by 7.84h compared to a single treatment with oseltamivir (mean difference, -7.84; 95% CI, -12.51 to -3.17; p=0.001). Herbal medicine compared to placebo showed a significantly better total effective rate (risk ratio, 1.90; 95% CI, 1.18 to 3.07; P=0.008), herbal medicine compared to oseltamivir indicated significantly better effective rate (risk ratio, 1.15; 95% CI, 1.03 to 1.29; P=0.01), and combined treatment showed a significantly better total effective rate compared to a single treatment with oseltamivir (risk ratio, 1.20; 95% CI, 1.06 to 1.36; P=0.004). Regarding safety, no serious adverse events were reported in HM treatment. HM presented fewer adverse events compared to oseltamivir, but the difference was not significant (risk difference, -0.04; 95% CI, -0.09 to 0.00; P=0.08), and the combined treatment did not increase adverse events compared to oseltamivir (risk difference, -0.02; 95% CI, -0.06 to 0.02; P=0.30). Research findings show that herbal medicine treatments have beneficial therapeutic effects on influenza and could decrease duration of fever and improve total effective rate. In addition, herbal medicine plus oseltamivir combined therapy could increase the therapeutic effect compared to a single treatment with oseltamivir.