Ban Xia (pinellia) is a toxic medicinal, and has been subjected to pao zhi to reduce its toxicity since ancient times.  Sheng (unprocessed) Ban Xia is still used for external applications, but all internal applications generally use processed Ban Xia.  A variety of forms are found on the market today, and over a dozen processing methods have been used historically.  Today, the most common forms of Ban Xia are Jiang Ban Xia (ginger pinellia) and Fa Ban Xia (standard pinellia), though Qing Ban Xia (a more simple preparation method) and Ban Xia Qu (a fermentation method similar to that used for Shen Qu) can also be found.

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Ginger has been used in the processing of Ban Xia since ancient times, and the two are often paired together in prescriptions because ginger reduces Ban Xia's toxicity while strengthening its ability to harmonize the stomach to treat vomiting.  Alum (Bai Fan) and ginger are used in multiple processing styles, but there are some key differences in the method used for Fa Ban Xia vs. Jiang Ban Xia.

Fa Ban Xia is made by a much more complex process, and it involves soaking the Ban Xia in a limestone solution and decocted licorice solution that is highly alkaline (pH is maintained over 12). For every 100 kg of Ban Xia, 10 kg of limestone and 15 kg of licorice (Gan Cao) are used.

Jiang Ban Xia is made by boiling Ban Xia with a decoction of ginger and alum (Bai Fan), and uses 25 kg of fresh ginger and 12.5 kg of alum for every 100 kg of Ban Xia.  This form is preferred for vomiting, while Fa Ban Xia tends to be preferred for treating cold phlegm.