Pinellia (Pinellia ternata), known as "Ban Xia" in Traditional Chinese Medicine (TCM), has been used for centuries in East Asian medicine, primarily for its effects on the respiratory system. It is a key ingredient in several classic TCM formulas, such as "Er Chen Tang," which is used to address symptoms like cough, phlegm, and congestion. In TCM theory, Pinellia is said to "transform phlegm" and "dry dampness," which aligns with its use for sinus-related issues such as nasal congestion and post-nasal drip.

However, there is limited modern scientific research directly validating Pinellia’s effectiveness for sinus health by Western standards. Most of the support for its use comes from traditional usage and empirical observations rather than rigorous clinical trials. Laboratory studies have identified some bioactive compounds in Pinellia, but safety concerns exist, as raw Pinellia is considered toxic and must be properly processed before use. While some animal and in vitro studies suggest anti-inflammatory and antitussive effects, these have not been robustly demonstrated in human clinical trials specifically for sinus or upper respiratory conditions.

In summary, the use of Pinellia for supporting sinus health is primarily justified by traditional use in TCM rather than modern scientific evidence.