Cassia Bark

Traditional Use

Primary Actions

• 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.

Secondary Actions

• Rou Gui is stronger, deeper, and more interior-warming than Gui Zhi because it comes from mature bark rather than younger twigs, so the two are related but not interchangeable.
• The bark is often added late in decoction or taken as powder so that its aromatic warming oils are not driven off by prolonged boiling.

Classic Formulas

• 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.

Classical References

• 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.