Echinacoside is a natural phenylethanoid glycoside primarily found in Echinacea species and Cistanche. It has drawn attention due to its potential antiviral and immunomodulatory properties. Preclinical studies, mostly in vitro and in animal models, have demonstrated that echinacoside can inhibit the replication of certain viruses, such as influenza virus and herpes simplex virus, and modulate immune responses by enhancing macrophage activity and cytokine production. However, most of this research is preliminary and mechanistic in nature, rather than clinical.

Human clinical trials directly evaluating echinacoside as an isolated compound for viral infection support are lacking. Some studies on Echinacea extracts (which contain echinacoside among other constituents) have shown modest benefits in reducing the duration or severity of viral upper respiratory infections, but results are inconsistent, and it is difficult to attribute observed effects specifically to echinacoside.

Overall, there is some scientific rationale, supported by laboratory studies, for the potential antiviral effects of echinacoside. However, the direct clinical evidence in humans is very limited, and further research—including well-designed human trials—is needed before its antiviral use can be strongly recommended. Thus, the evidence rating is 2 out of 5.