Xiao Yao San vs. Gui Pi Tang

Both formulas appear constantly in practice for low mood, fatigue, and stress — but they answer different questions. The difference is where the problem starts.

The one-line difference

Xiao Yao San treats constraint — qi that is stuck and pressing on a weakened spleen. Gui Pi Tang (归脾汤, "Restore the Spleen Decoction") treats depletion — a spleen and heart worn down until the blood that houses the spirit runs thin^[1].

When each fits

Xiao Yao San's picture is tension: irritability, sighing, moodiness that tracks stress, premenstrual breast tenderness, symptoms that flare under pressure and ease with movement or venting.

Gui Pi Tang's picture is exhaustion: overthinking and worry rather than anger, poor memory, palpitations, insomnia of the lying-awake-tired kind, pale complexion, and bleeding issues the tradition ties to a spleen too weak to hold blood^[1].

Can they overlap?

Constantly — long-standing constraint depletes, and depletion frustrates. Practitioners often move from one to the other as the picture shifts, or use established combinations of the two families. Which one leads is a pattern call: dominant tension points to Xiao Yao San, dominant depletion to Gui Pi Tang.

This page describes traditional differential logic; it is not a recommendation. The safety notes apply to both formulas.