Glycyrrhizic acid, a principal component of licorice root (Glycyrrhiza glabra), has been studied for its antiviral properties, including activity against the influenza virus. Several in vitro studies have demonstrated that glycyrrhizic acid can inhibit the replication of influenza A viruses by interfering with viral attachment and entry, as well as modulating immune responses such as suppressing pro-inflammatory cytokine production. For example, research published in peer-reviewed journals (e.g., Antiviral Research, 2006; Planta Medica, 2012) has shown glycyrrhizic acid can reduce viral titers in cell cultures infected with influenza strains.

However, evidence from animal studies is limited, and robust clinical trials in humans are lacking. Most available data are preclinical, and there is insufficient evidence to recommend glycyrrhizic acid as a treatment for influenza in humans. Safety is also a concern, as excessive consumption of glycyrrhizic acid can lead to adverse effects such as hypertension and hypokalemia. Thus, while there is a scientific basis for its potential antiviral effects, the evidence supporting its effectiveness for influenza is preliminary and not yet translated to clinical practice.