Which ingredient has the highest maximum dosage in Bai Tou Weng Tang?

• A. Huang Lian
• B. Qin Pi
• C. Bai Tou Weng
• D. Huang Bai

Answer: (C)

The key idea here is that in a classic formula, the main problem is tackled by the herb used in the largest amount. Bai Tou Weng Tang treats dysentery caused by heat-toxin in the intestines, and Bai Tou Weng (Pulsatillae Radix) is the principal herb that clears that intestinal heat-toxin most strongly. Because of its central role, it is used in the largest dose among the four ingredients. The other three herbs—Huang Lian, Huang Bai, and Qin Pi—support the action by clearing heat and dampness in different areas, so they are dosed smaller. In typical preparations, Bai Tou Weng is around 12 g, while the others are about 6 g each, which is why Bai Tou Weng has the highest maximum dosage.