《病机机要》曰∶有表而热者，谓之表热；无表而热者，谓之里热；有暴热而为热者，
乃久不宣通而致也。有服温药而为热者，有恶寒战栗热者。及其治也，小热之气，凉以取之；
大热之气，寒以取之；甚热之气，以汗发之。发之不尽，则逆制之。制之不尽，求其属以
衰之。苦者治脏，脏属阴而居内；辛者治腑，腑属阳而在外。故内音下之，外者发之。又宜
养血益阴，其热自愈。
东垣曰∶发热恶热，大渴不止，烦躁肌热，不欲近衣，其脉洪大，按之无力者，或无
目痛，鼻干者，非白虎汤证也。此血虚发躁，当以当归补血汤主之。又有火郁而热者，如不
能食而热，自汗气短者，虚也，以甘寒之剂泻热补气。非如能食而热，口舌干燥，大便难者，
以辛苦大寒之剂下之，非泻热补水之比。当细分之，不可概论。如言烦躁，虚烦亦与实烦
不同。如伤寒烦者，为真阳内郁，阴中伏阳之证，与阴虚燥热，病本亦异。
东垣曰∶仲景论内外不足发热、自汗之证，大禁发汗。若饮食劳倦，杂病发热，身汗，
表虚之证认作有余，便用发汗，则表益虚也。
心热者，微按至皮肤之下，肌肉之上，轻手乃得。微按至皮毛之下热，少加力按之，
则全不热，是热在血
脉也。其证心烦，心痛，掌中热而哕，以黄连泻心汤、导赤散。实则泻心汤，虚则朱砂安神
丸。肺热者，轻手乃得，微按全无，日西热甚，乃皮毛之热，其证必见喘咳。寒热轻者，
泻白散，实则凉膈散，虚则人参白虎汤。
肝热者，重按之，肌肉之下至骨之上，乃肝之热，当寅卯间尤甚。其脉弦，四肢满闷，
便难，转筋，多怒多惊，四肢困热，筋痿不能起于床者，泻青丸。实则柴胡饮子。
脾热者，轻手扪之不热，重按至筋骨又不热，不轻不重，在轻手重手之间，热在肌肉，
过夜尤甚，其证必怠情，嗜卧，四肢不收，无气以动，泻黄散。实则调胃承气汤，虚则人参黄
散。
肾热者，轻手重手俱不热。如重手按至骨分，其蒸热手如火，其人骨苏苏如虫蚀，其骨
困热不任，亦不能起于床，实则滋肾丸，本滋阴法也。无实不可泻。气实脉盛，身热烦扰，宜
三一承气汤、凉膈散等药下之。热在中，四顺清凉饮，在下八正之类。夜热多，或有汗，或鼻
衄，身热而便难，四物去芎加黄连、生地、地骨皮之类。日热多，热在气分，柴胡饮子、
白虎汤。有轻手按之热甚，重手取之不甚热，此热在肌表，宜清之。竹茹、竹叶、地骨皮、
麦门冬之类。有神气怫郁而热，宜清神散。热在上而阴水不升，阴火腾沸，宜升阳泻火法，虚
者补之。初病阳证而失于下，至变似阴，而不可用白虎汤之类。有食伤太阴而热，或停食而
下之，痰液不散，郁结成热，宜导开之。因积滞而蓄热，当先损积而热自退。有丹毒热肿，
气郁结滞，并可解散，随证用药。此候欲发疮毒，分六淫治。坠浮留之火，须紫雪、朱砂、
琥珀、犀角之类。阴虚精滑，元气脱者，用滋阴药，燥者润之。（方法见燥门。）有蓄血证者，
宜下之。汗下后，元气虚而下陷，阴阳之气揭薄而不起，为虚热，宜与来复丹、灵砂丹之类。
汗下后，脉燥、身热、大渴饮水不已者，先掘井泉，取水饮之。有郁冒诸风为热，宜防风通圣
散，川芎、石膏之类。有肺燥郁热，或火乘之者，宜清之，白虎汤加地骨皮。元气不足，胃气
下陷为热，宜补中益气汤，血虚者加血药。从治，药使酒煎，或湿热为佐使；反治，蜜煎鸟头
之类。其候欲发斑疹、身热者，升麻汤之类发之。
The *Bingji Jingyao* (Essentials of Pathogenesis) states: When there is an exterior pathogen and fever, it is called Exterior Heat (Biao Re); when there is no exterior syndrome but fever occurs, it is called Interior Heat (Li Re). Sudden onset of persistent fever is caused by long-term stagnation and lack of free flow of Qi. There are also cases where fever results from taking warm-tonifying medicines, or cases accompanied by aversion to cold and shivering. Regarding treatment: for mild heat, cool-natured herbs are used to clear it; for severe heat, cold-natured herbs are used to purge it; for extreme heat, diaphoresis (sweating method) is employed to disperse it. If dispersal fails to eliminate the pathogen completely, contrary suppression methods (e.g., treating heat with cold) are applied. If suppression still fails, one seeks the root cause associated with the disease to weaken its intensity. Bitter herbs treat Zang organ diseases because Zang organs belong to Yin and reside internally; Acrid herbs treat Fu organ diseases because Fu organs belong to Yang and reside externally. Therefore, interior conditions are treated with purgation, while exterior conditions are treated with diaphoresis. Additionally, nourishing Blood and benefiting Yin should be practiced, so that the heat heals itself.
Li Dongyuan said: Symptoms such as fever, aversion to heat, unquenchable thirst, restlessness, muscle heat, and a desire not to wear clothes, with a洪大 (Hóng Dà, surging) pulse that is empty upon deep pressure, or without eye pain and dry nose, do not constitute a Baihu Tang (White Tiger Decoction) syndrome. This is irritability caused by Blood deficiency, and Danggui Buxue Tang (Angelica Sinensis Decoction for Tonifying Blood) should be the primary prescription. There are also cases of heat due to Fire stagnation, such as inability to eat yet having fever, spontaneous sweating, and shortness of breath, which indicate a Deficiency syndrome; these should be treated with sweet-cold agents to purge heat and tonify Qi. This is unlike cases where the patient can eat yet has fever, dry mouth and tongue, and difficult defecation, which require bitter-acrid great-cold agents for purgation; these two situations are not comparable in terms of purging heat and replenishing fluids. They must be carefully distinguished and cannot be generalized. For instance, regarding irritability, Deficient Irritability (Xu Fan) differs from Excess Irritability (Shi Fan). In Shanghan (Cold Damage), irritability is due to the internal stagnation of True Yang and latent Yang within Yin, which differs fundamentally from the pathology of Yin deficiency with dry-heat.
Li Dongyuan further stated: Zhang Zhongjing discussed fevers and spontaneous sweating caused by internal and external insufficiency, strictly prohibiting the use of diaphoresis. If miscellaneous diseases caused by dietary irregularities and overwork present with fever, sweating, and exterior deficiency, mistaking them for Excess syndromes and using diaphoresis will further weaken the exterior Qi.
When the Heart has heat, light palpation below the skin and above the muscles reveals heat; however, if slight pressure is applied below the hair follicles and more force is added, the heat disappears completely, indicating the heat resides in the Blood vessels. Symptoms include heart vexation, heart pain, heat in the palms, and hiccups. These are treated with Huanglian Xiexin Tang (Coptis Decoction to Drain the Heart) or Daochi San (Guide Out Red Powder). For Excess patterns, Xiexin Tang is used; for Deficiency patterns, Zhusha Anshen Wan (Cinnabar Calming the Spirit Pill) is used. When the Lungs have heat, light palpation reveals heat, but slight pressure makes it vanish; the heat worsens in the late afternoon (Ding West), indicating heat in the skin and hair. Symptoms necessarily include wheezing and coughing. For mild heat, Xiebai San is used; for Excess patterns, Liangge San is used; for Deficiency patterns, Renshen Baihu Tang is used. When the Liver has heat, heavy pressure below the muscles and above the bones reveals liver heat, which is particularly severe during the Yin-Mao hours (3 AM–7 AM). The pulse is Wiry (Xian), accompanied by fullness and stuffiness in the four limbs, difficult defecation, tendon spasms, irritability,惊惧 (fright/fear), heat in the limbs, and tendon flaccidity preventing the patient from rising from bed. These are treated with Xieqing Wan. For Excess patterns, Chaihu Yinzi is used. When the Spleen has heat, light palpation does not reveal heat, nor does heavy pressure to the bones; the heat is found between light and heavy pressure, residing in the muscles, and is worse at night. Symptoms include lethargy, drowsiness, inability to hold the four limbs, and lack of Qi to move. These are treated with Xiehuang San. For Excess patterns, Tiaowei Chengqi Tang is used; for Deficiency patterns, Renshen Huangqi San is used. When the Kidneys have heat, neither light nor heavy palpation reveals surface heat. However, heavy pressure to the bone level reveals steaming heat like fire, with a sensation of bone soreness as if bitten by insects, and bone heat making the patient unable to rise from bed. For Excess patterns, Zishen Wan is used, following the method of nourishing Yin. Purging should not be used without Excess patterns. If Qi is Excess and the pulse is robust, with body heat and restlessness, Sanyi Chengqi Tang or Liangge San should be used for purgation. Heat in the Middle Jiao is treated with Sishun Qingliang Yin; heat in the Lower Jiao is treated with Bazheng San. Nighttime fever with sweating or epistaxis, body heat, and difficult defecation are treated with Siwu Tang minus Chuanxiong, plus Huanglian, Shengdi, and Digupi. Daytime fever predominating indicates heat in the Qi level, treated with Chaihu Yinzi or Baihu Tang. Heat that is intense on light palpation but less so on heavy palpation indicates heat in the muscle layer/exterior, treated with clearing methods using Zhuru, Zhuye, Digupi, and Maidong. Heat due to Shen Qi (Spirit Qi) depression is treated with Qingshen San. Heat in the Upper Jiao with failure of Yin Water to ascend and boiling Yin Fire is treated with the method of raising Yang and draining Fire; Deficiency patterns are tonified. Initial Yang syndromes mishandled with purgation may transform into apparent Yin syndromes, where Baihu Tang should not be used. Heat from dietary injury to the Taiyin Spleen, or heat formed from retained food after mistaken purgation leading to unresolved phlegm-fluids and stagnation, should be treated with guiding and opening methods. Heat accumulated due to stagnation requires first resolving the accumulation, after which the heat subsides. Erysipelas with red swelling due to Qi stagnation and blockage can be resolved with dispersing methods according to the syndrome. Syndromes predisposing to sores and toxins are treated according to the Six Evils (Liu Yin). Lingering floating Fire requires Xuexue, Zhusha, Hupo, and Xijiao. Yin deficiency with essence slipping and Yuan Qi collapse requires Yin-nourishing drugs; dryness is moistened. (Methods see the Dryness section.) Blood stasis syndromes require purgation. After sweating or purging, if Yuan Qi is deficient and sinks, causing Yin and Yang Qi to separate and fail to recover, resulting in Deficient Heat, Laifu Dan or Lingsha Dan should be used. After sweating or purging, if the pulse is restless, body is hot, and there is unquenchable thirst, drinking water from a newly dug well spring is recommended. Heat from various Wind pathogens causing Yu Mao (depression/dizziness) is treated with Fangfeng Tongsheng San, including Chuanxiong and Shigao. Lung dryness with stagnant heat or Fire invasion is treated with clearing methods, such as Baihu Tang plus Digupi. Heat caused by insufficient Yuan Qi and sinking Stomach Qi is treated with Buzhong Yiqi Tang; Blood deficiency cases add Blood-tonifying herbs. Following the principle of "Cong Zhi" (following/treating similarly), herbs are decocted with wine, or damp-heat herbs are used as guides; following "Fan Zhi" (contrary treatment), honey-decocted Wutou is used. Syndromes predisposing to macules and rashes with body heat are treated with Shengma Tang to disperse them.