邪热聚于胃腑，消耗津液，故口干、热而渴也。经曰少阴病，故口燥咽干者，急下之。若不口
燥咽干而渴，脉沉者，急温之。又有漱水不下咽者，若见表证，必衄，为邪热在经也。以血气俱多，
经中热甚、迫血妄行而作衄者，无表证，加之胸腹满而如狂者，又为蓄血在内者。
阳明口燥咽干，无大热，背微恶寒，烦渴，白虎加人参汤。
少阳口燥咽干，小柴胡汤。
少阴口燥咽干而渴，急下之，用承气汤。
阳明病，口燥欲漱水不咽者，必衄，黄芩芍药汤；漱水不咽，发狂，轻者犀角地黄汤，甚者抵
当汤。
渴者，里有热也。津液为热所耗，故令渴也。伤寒六七日，传至厥阴，为消渴者，渴饮水多而
小便少，乃热能消水也。朱氏曰∶脉浮而渴，属太阳；有汗而渴，属阳明；自利而渴，属少阴。至
于厥阴，则又热之极矣。太阳无汗，若渴，忌白虎，宜柴胡汤。阳明多汗而渴，戒五苓，宜竹叶石
膏汤。若先呕后渴，则为欲解，当与之水。先渴后呕，则为水停，属赤茯苓汤。当从此议，勿令误
也。
太阳病，发渴，脉浮，表不解，心下有水气，小青龙汤去半夏，加栝蒌。服桂枝汤，汗出后烦
渴甚者，白虎加人参汤。小便不利而渴，五苓散。身热恶风，手足
温，胁满而渴，小柴胡去半夏，加栝蒌。
阳明发渴，则有汗，胁下硬，不大便而呕，舌上白苔，小柴胡汤加减同用。若汗少，小便不利，
脉浮而渴，五苓散；渴而饮水呕者，同。
发黄，头汗出，小便不利，渴饮水浆，茵陈蒿汤、茵陈五苓散。
少阳发汗，则自利，咳而呕，引水饮，猪苓汤。
下利，渴欲饮水，白头翁汤。下利，脉数而渴者，自愈；不愈，必下清血，宜黄芩散。
病患脉微细，欲吐不吐，心烦但寐，小便白，下利而渴，四逆汤。
邪热聚集于胃腑，消耗津液，因此出现口干、身热且口渴的症状。《内经》记载：少阴病中，若出现口燥咽干的情况，应当紧急使用泻下法治疗。如果并非口燥咽干而是感到口渴，且脉象沉伏的，应当紧急使用温里法治疗。又有那种想含水漱口却不肯咽下的情况，如果同时表现出表证，必然会出现鼻衄（鼻出血），这是因为邪热在经络所致。如果气血充盛，经络中热势极盛，逼迫血液妄行而导致鼻衄的，没有表证；如果再加上胸腹部胀满且神志狂乱如痴的，则是体内有蓄血证。
阳明经病变导致口燥咽干，体表没有大热，背部微微恶寒，心烦且口渴，适用白虎加人参汤。
少阳经病变导致口燥咽干，适用小柴胡汤。
少阴经病变导致口燥咽干且口渴，应当紧急泻下，适用承气汤。
阳明病中，口燥想含水漱口但不愿咽下的，必然会出现鼻衄，适用黄芩芍药汤；如果是含水漱口不咽且发狂的，轻症适用犀角地黄汤，重症适用抵当汤。
口渴，说明体内有热。津液被热邪耗伤，所以导致口渴。伤寒病经过六七天，传入厥阴经，出现消渴症状的，表现为喝水多而小便少，这是热能消耗水液的表现。朱氏说：脉象浮且口渴的，属于太阳病；有汗且口渴的，属于阳明病；自发性腹泻且口渴的，属于少阴病。至于厥阴病，则是热邪到了极点。太阳病无汗，如果出现口渴，忌用白虎汤，宜用柴胡汤。阳明病多汗且口渴，忌用五苓散，宜用竹叶石膏汤。如果先呕吐后口渴，说明病将要解除，可以给予饮水。如果先口渴后呕吐，说明是水饮停聚，属于赤茯苓汤的主治范围。应当遵循这些原则，不要误治。
太阳病，出现口渴，脉象浮，表证未解，心下有停水，适用小青龙汤去掉半夏，加入栝蒌。服用桂枝汤后，出汗后反而严重烦渴的，适用白虎加人参汤。小便不利且口渴的，适用五苓散。身体发热、怕风，手足温暖，胁部胀满且口渴的，适用小柴胡汤去掉半夏，加入栝蒌。
阳明病出现口渴，则伴有出汗，胁下硬满，大便不通且呕吐，舌苔白，适用小柴胡汤加减同用。如果汗少，小便不利，脉象浮且口渴的，适用五苓散；口渴且饮水后呕吐的，也适用此方。
出现发黄，头部出汗，小便不利，口渴想喝饮料的，适用茵陈蒿汤或茵陈五苓散。
少阳病误用发汗法，则导致自发性腹泻，咳嗽且呕吐，引水饮用，适用猪苓汤。
When pathogenic heat accumulates in the Stomach Fu (Stomach organ), it consumes Body Fluids (Jin Ye), resulting in dry mouth, heat sensation, and thirst. The Classics state: In Shaoyin disease, if there is dryness of the mouth and dryness of the throat, urgent purgation (Xia Fa) is required. If, however, there is no dryness of the mouth and throat but rather thirst, and the pulse is deep (Chen), urgent warming (Wen Fa) is required. There is also the condition where one rinses the mouth with water but does not swallow it; if exterior signs are present, epistaxis (Niu) will inevitably occur, indicating that pathogenic heat is in the meridians. If Qi and Blood are abundant, and heat in the meridians is severe, forcing blood to move recklessly causing epistaxis without exterior signs; or if accompanied by fullness in the chest and abdomen and mania-like behavior, this indicates accumulation of blood (Xu Xue) inside.
In Yangming channel pathology, dryness of the mouth and throat, absence of significant surface heat, slight aversion to cold on the back, irritability, and thirst are treated with Baihu Jia Renshen Tang (White Tiger Decoction plus Ginseng).
In Shaoyang channel pathology, dryness of the mouth and throat is treated with Xiaochaihu Tang (Minor Bupleurum Decoction).
In Shaoyin channel pathology, dryness of the mouth and throat with thirst requires urgent purgation, using Chengqi Tang (Gut-Draining Decoction).
In Yangming disease, dryness of the mouth with a desire to rinse the mouth but not swallow indicates inevitable epistaxis, treated with Huangqin Shaoyao Tang (Scutellaria and Peony Decoction); if rinsing the mouth without swallowing is accompanied by mania, mild cases are treated with Xijiao Dihuang Tang (Rhinoceros Horn and Rehmannia Decoction), and severe cases with Didang Tang (Definitely Invading Decoction).
Thirst indicates interior heat. Body Fluids are consumed by heat, leading to thirst. After six or seven days of Shanghan (Cold Damage), when the disease transmits to the Jueyin channel, Xiao Ke (Consumptive Thirst) occurs, characterized by drinking much water but producing little urine, as heat consumes water. Zhu states: Pulse floating with thirst belongs to Taiyang; sweating with thirst belongs to Yangming; spontaneous diarrhea with thirst belongs to Shaoyin. As for Jueyin, it represents the extreme of heat. In Taiyang disease without sweat, if thirst occurs, Baihu Tang is contraindicated; Chaihu Tang is appropriate. In Yangming disease with profuse sweating and thirst, Wuling San is contraindicated; Zhuye Shigao Tang (Bamboo Leaf and Gypsum Decoction) is appropriate. If vomiting precedes thirst, it indicates the disease is resolving, and water may be given. If thirst precedes vomiting, it indicates fluid retention, treated with Chi Fuling Tang (Red Poria Decoction). One must follow these principles to avoid error.
In Taiyang disease, thirst with a floating pulse and unresolved exterior condition, along with fluid retention in the Heart region (Xia), is treated with Xiao Qinglong Tang (Minor Green Dragon Decoction) with Banxia removed and Gualou added. After taking Guizhi Tang, if profuse sweating leads to severe irritability and thirst, Baihu Jia Renshen Tang is used. Difficulty in urination with thirst is treated with Wuling San (Five-Ingredient Powder with Poria). Fever, aversion to wind, warm hands and feet, hypochondriac fullness, and thirst are treated with Xiaochaihu Tang with Banxia removed and Gualou added.
In Yangming disease, thirst is accompanied by sweating, hardness under the hypochondrium, constipation, and vomiting, with a white tongue coating; Xiaochaihu Tang is used with modifications. If sweating is scant, urination is difficult, the pulse is floating, and there is thirst, Wuling San is used; this also applies if thirst and drinking water lead to vomiting.
Jaundice with head sweating, difficulty in urination, and thirst for fluids is treated with Yinchen Hao Tang (Artemisiae Scopariae Decoction) or Yinchen Wuling San.
If Shaoyang disease is incorrectly treated with diaphoresis (sweating-inducing methods), it leads to spontaneous diarrhea, cough, vomiting, and a desire to drink water; Zhuling Tang (Polyporus Decoction) is used.
Diarrhea with thirst and a desire to drink water is treated with Baitouweng Tang (Pulsatilla Decoction). Diarrhea with a rapid pulse and thirst will resolve spontaneously; if it does not resolve, clear bloody stools will appear, and Huangqin San (Scutellaria Powder) is indicated.
If the patient has a faint and fine pulse, a desire to vomit but inability to do so, irritability with only a desire to sleep, white urine, diarrhea with thirst, Sini Tang (Frigid Extremities Decoction) is used.