Baicalin is a flavonoid compound isolated from the roots of Scutellaria baicalensis (Chinese skullcap), a traditional Chinese medicinal herb. Its use for colds and viral infections has roots in traditional Chinese medicine, but significant laboratory research has also explored its antiviral properties. In vitro and some in vivo studies have shown that baicalin can inhibit the replication of several viruses associated with respiratory infections, including influenza viruses and certain coronaviruses. The proposed mechanisms include inhibition of viral neuraminidase, suppression of viral RNA synthesis, and modulation of the immune response (notably by reducing pro-inflammatory cytokines).

However, while these preclinical results are promising, robust clinical evidence in humans is lacking. Most studies to date are limited to cell culture or animal models. A few small clinical trials suggest potential benefits in symptom reduction and illness duration when baicalin-containing herbal formulas are used, but these studies often have methodological limitations or confounding factors. As such, current evidence supports a potential antiviral effect, but it is insufficient to conclusively recommend baicalin as a treatment for colds in humans. Its use is best described as supported by preliminary scientific evidence, warranting further investigation.