Medical use
Cinnamon Bark has a acrid, sweet and very warm. It is use as tonic for stomach, rid of wind, to promote sweating, for headache, anemia, cold limbs, to promote urination. It help promote lung qi, in chill and fever, cold phlegm, diarrhea, muscle spasm, headache, back pain, sweating, to stop easily being annoyed, strengthening muscles and bones, promote circulation. It use in impotence due to lack of fire.
1.the ingredient cinnamaldehyde posseses antipyretic effect; promote sweating, diluting blood vessel of the skin (if decoction is used when warm).
2.anti-spasm, relieves pain; inhibits CNS.
3.inhibit the induced ulcers of laboratory rats; promotes bile secretion. ? antibiotic effect.
4.lowers blood sugar (methylhydroxy chalcone polymer ).
5.promote urination (if decoction is used when cooled).

Cinnamon Bark should not be use in case of warm-febrile diseases, giddiness [yinxu] with heat, heat in blood with vomiting. Use caution during pregnancy or excessive bleeding during menses. Over dosage may be toxic to the kidney and may cause bleeding in the urinary tract.

Cinnamon Bark (Rou Gui)Note:
Rou Gui is the thick bark of the trees.
Gui zhi is from the young branches of cinnamon trees.
Usually Cinnamon Bark (Rou Gui) is used in tonic while Gui Zhi is used for expelling wind and dampness but they can be used interchangeably.