Gui Zhi is a kind of Chinese herbal medicine, which is the dried shoots of cinnamon of the camphor family. Cinnamon sticks are pungent, sweet and warm in nature, and are attributed to the heart, lung and bladder meridians. It has the efficacy of sweating and relieving muscles (relieving the evil qi on the surface of the skin), warming the meridians, assisting yang in transforming qi, and calming the flushing and descending qi, and is mostly used in the treatment of wind-cold colds, cold pain in the epigastric region (cold pain in the stomach and abdomen), blood-cold menstrual occlusion, paralytic pain in the joints, phlegm (a pathological product of impaired metabolism of fluids), and oedema in clinical practice. However, due to the warm nature of Gui Zhi, it is easy to injure the yin and move the blood, so it is contraindicated for those who have external fever, yin deficiency (deficiency of yin and essence in the body, and hyperactive fire), and blood heat, so as to avoid further damage to the yin fluid and aggravation of the yin deficiency. In addition, pregnant women, menstruating people should be cautious.