Which formula treats both yin and yang?

• A. Wu Ling San
• B. Er Xian Tang
• C. Gui Zhi Fu Ling Wan
• D. Xue Fu Zhu Yu Tang

Answer: (B)

Understanding yin and yang balance is key here. When a patient shows signs of both yin and yang deficiency, you need a formula that nourishes yin while also supporting yang. Er Xian Tang is designed to do exactly that—it combines components that replenish kidney yin with components that strengthen kidney yang. This dual action helps address the internal heat and dryness from yin deficiency at the same time as the reduced warmth and vitality from yang deficiency, so it’s the best fit for a pattern where both aspects are deficient. The other formulas target more singular patterns—damp-heat, blood stasis, or chest stagnation—and don’t provide the same simultaneous dual nourishment.