In Si Wu Tang, which herb serves as the deputy?

• A. Bai Shao
• B. Dang Gui
• C. Shu Di Huang
• D. Huo Xiang

Answer: (B)

In Si Wu Tang, the deputy is the herb that supports the main blood-nourishing action by tonifying and invigorating blood, helping to move it so nourishment can reach the whole body. Dang Gui (Angelica sinensis) fits this role well because it tonifies blood and enhances blood movement, working alongside Shu Di Huang’s blood-nourishing effect to address blood deficiency with better circulation and reform. Huo Xiang is not a component of Si Wu Tang, so it cannot be the deputy. Bai Shao also nourishes blood and preserves Yin, but within this formula its role is not the deputy position; Dang Gui is considered the auxiliary that strengthens and directs the blood-related actions of the formula.