The formula of Returning Yang may refer to the Four Reversals Tang in Zhang Zhongjing’s Treatise on Typhoid Fever, which consists of three herbs: epiphyllum, dry ginger, and licorice. Si Reverse Tang has the efficacy of returning yang to save the body (by warming yang qi to save fainting, unconsciousness, etc.). It is mainly used for treating Shaoyin disease (illnesses caused by the invasion of the Shaoyin meridian by an exogenous pathogen), and cold syncope caused by the decline of Yang in the heart and kidneys. Symptoms include syncope of the limbs (unconsciousness, accompanied by cold extremities, even to the elbows and above the knees), coldness (fear of cold), curling up in the bed, weakness of the spirit and desire to sleep, pallor, abdominal pain and discharging of fluid. Si Reverse Tang can also be used to treat sun disease (wind-cold evil qi attacking the body’s muscle surface and manifesting as fear of cold and fever, head and body pain, and floating pulse) with misplaced sweating and loss of yang. This formula is purely with hot and pungent products, in the sick hands and feet mild, not long service. It should not be taken for a long time. It is forbidden for those with true heat and false cold. If Si-Yi Tang is to be used, it must be used under the guidance of a medical professional.