Chinese Thorowax Root Classic Formulas … Natural Herb Library

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Harmonizes Shaoyang disorders ... Chai Hu is one of the classic herbs for alternating fever and chills, bitter taste, rib-side fullness, and the half-exterior half-interior pattern that is neither fully released nor fully internalized.
Spreads Liver qi and relieves constraint ... it is used for flank distention, emotional frustration, poor appetite from constrained qi, and some menstrual or digestive patterns where stagnation rather than deficiency dominates.
Raises clear yang and lifts sinking qi ... in appropriate formulas it helps treat prolapse, chronic diarrhea, and fatigue patterns where the middle burner fails to lift.

Xiao Chai Hu Tang ... the signature Shaoyang-harmonizing formula built around Chai Hu.
Si Ni San ... classic course-the-Liver and regulate-qi formula when internal constraint affects the limbs, chest, or digestion.
Bu Zhong Yi Qi Tang and Chai Hu Shu Gan San ... examples of its lifting and qi-course functions in very different formula settings.

Materia medica tradition treats Chai Hu as the key herb for harmonizing Shaoyang and spreading constrained Liver qi rather than as a simple general antipyretic.
Its dual ability to course and to lift explains why it appears in both exterior-interior harmonizing formulas and middle-qi lifting formulas.