Cassia Bark Classic Formulas — Natural Herb Library

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Reinforces fire and supports Kidney and Spleen Yang - a major herb for cold limbs, sore low back, impotence, frequent urination, dawn diarrhea, and deep exhaustion when Ming Men fire is weak.
Disperses cold and alleviates pain - used for cold congealing in the abdomen, chest, epigastrium, or channels, especially when pain is fixed, better with warmth, and worsened by cold exposure.
Warms and unblocks the channels while moving Blood - classically selected for amenorrhea, dysmenorrhea, postpartum abdominal pain, cold Bi syndrome, and deep-rooted yin-type sores where cold and stasis knot together.
Guides floating deficient fire back to its source and helps the Kidneys grasp Qi - applied when false upper heat coexists with cold below or when Kidney Yang fails to anchor breathing.

You Gui Wan (右归丸) - classic Kidney-Yang restoring formula in which Rou Gui helps rekindle Ming Men fire, warm the lower burner, and strengthen reproductive and lumbar weakness.
Jin Gui Shen Qi Wan / Shen Qi Wan (金匮肾气丸) - foundational formula for Kidney-Yang deficiency with frequent urination, low back coldness, edema, and lower-body weakness, using Rou Gui to warm the source fire.
Yang He Tang (阳和汤) - external-surgery classic for deep cold-type abscesses and yin-type sores, where Rou Gui helps warm the channels, dispel cold, and move constrained Blood and phlegm.
Shao Fu Zhu Yu Tang (少腹逐瘀汤) - blood-stasis formula for cold-induced lower-abdominal pain and dysmenorrhea in which Rou Gui warms the channels so stasis can be dispersed.

Sacred Lotus records Rou Gui as spicy, sweet, and hot, entering the Heart, Kidney, Liver, and Spleen channels, and specifically cautions against use in Yin-deficiency fire, excess internal Heat, and pregnancy.
Traditional Rou Gui monographs summarized in TCM reference sources describe the bark as reinforcing fire, strengthening Yang, dispersing cold, and warming the channels for cold-stasis pain and deficiency-cold reproductive disorders.
TCM sources consistently distinguish Rou Gui from Gui Zhi by medicinal part and depth of action: bark is used for stronger interior warming, whereas twig is lighter and more surface-releasing.