《伤寒论·辨太阳病脉证并治中》
脉象浮，主病在表，当用发汗解表法治疗，如果用灸法治疗，表邪不能从汗解，邪热反而因火治法而更加炽盛，出现从腰以下沉重而麻痹，这就叫火逆。
脉浮，宜以汗解，用火灸之，邪无从出，因火而盛，病从腰以下必重而痹，名火逆也。
A floating pulse means that the disease is located externally, and the method of dispelling the exterior with diaphoretic herbs should be used. However, if moxibustion is used instead, the external evil cannot be dissipated through sweating. On the contrary, the evil heat intensifies due to the fire method, causing heaviness and numbness in the body below the waist, which is called fire reversal.