Licorice root (Glycyrrhiza glabra) has a long history of use in traditional medicine systems, such as Traditional Chinese Medicine (TCM) and Ayurveda, to support respiratory health, including the sinuses. In TCM, licorice root is considered a "harmonizer" herb and is added to many formulas to support lung function, soothe sore throats, and ease coughs, which can be associated with sinus discomfort. In these traditions, it is believed to help thin mucus and relieve inflammation in the upper respiratory tract, indirectly supporting sinus health.

However, direct scientific evidence specifically linking licorice root to improvements in sinus health or sinusitis is limited. Most modern research has focused on its anti-inflammatory, antiviral, and expectorant properties, which could theoretically help with sinus congestion by reducing mucous membrane inflammation and aiding mucus clearance. Some laboratory and animal studies suggest that glycyrrhizin, a key compound in licorice, has anti-inflammatory and immune-modulating effects.

While these properties provide a plausible mechanism for its traditional use in supporting the sinuses, robust clinical trials in humans specifically assessing licorice root for sinus conditions are lacking. Therefore, its use for this purpose today is justified mostly by tradition, with modest supporting evidence from related scientific research.