阳明有经、有腑。阳明经病，发热头痛，目痛鼻干，唇焦漱水，宜解肌，葛根汤；阳明
经病传腑，蒸热自汗，口渴饮冷，白虎加人参汤，此散漫之热，可清而不可下；阳明腑病，
热邪悉入于里，其证潮热谵语，腹满便闭，宜攻之，调胃承气汤，此结聚之热，徒清无益也
夫病当用承气，而只用白虎，则结聚之热不除；当用白虎而遽用承气，则散漫之邪复聚而
为结热之证。夫石膏、大黄，同一清剂，而举用不当，尚关成败，何况寒热相反者乎？甚矣！
司命之难也。
或问∶经曰∶有太阳阳明，有少阳阳明，有正阳阳明，何也？答曰∶太阳阳明，由太阳
经传入阳明之腑也；少阳阳明，由少阳经传入阳明之腑也；正阳阳明，由阳明本经而传入本
腑也。大法，太阳阳明，太阳证不解，必从太阳解表为主。若表证不解，医误下之，转属阳
明，宜下之，小承气汤。若因误下而成结胸，先服小陷胸汤，若不瘥，再服大陷胸汤。余邪
未尽，投以枳实理中丸，应手而愈。少阳阳明，脉纯弦者，名曰负。负者，胜负也，为难治
若少阳证多者，必从少阳和解为先，小柴胡汤。若腹满硬痛，便闭谵语者，下之，大柴胡
汤。正阳阳明，在表者，葛根汤。表邪入里，未结聚者，白虎汤。邪已入腑，结聚成实者下
之，调胃承气汤。凡用下药，必以腹满、硬痛、便闭为主，或兼下利肠垢，或下利清黄水，
色纯青，心下硬，其中有燥屎也，攻之。否则虽不大便，亦未可攻，但清之、润之而已
阳明经病分为经证和腑证。阳明经证，表现为发热、头痛、眼睛疼痛、鼻子干燥、嘴唇焦枯、想漱口但不欲吞咽，适宜使用解肌法，方用葛根汤；若阳明经证传入腑证，出现蒸蒸发热、自汗出、口渴喜冷饮的症状，这是散漫的热邪，可以清热但不可攻下，方用白虎加人参汤；若是阳明腑证，热邪完全入里，症状为潮热、说胡话（谵语）、腹部胀满、大便不通，适宜攻下，方用调胃承气汤，这是结聚的热邪，单纯清热没有益处。
应当使用承气汤类方剂攻下时，如果只用白虎汤清热，那么结聚的热邪就无法消除；应当使用白虎汤清热时，如果急于使用承气汤攻下，那么原本散漫的邪气会重新聚集形成结聚的热证。石膏和大黄虽然都是清热药，但如果使用不当，尚且关系到治疗的成败，何况是寒热性质相反的药物呢？由此可见，医生治病救人是非常困难的。
有人问：医经中说：“有太阳阳明，有少阳阳明，有正阳阳明”，这是什么意思？回答说：太阳阳明，是由太阳经传入阳明腑的；少阳阳明，是由少阳经传入阳明腑的；正阳阳明，是由阳明本经直接传入本腑的。一般原则是，对于太阳阳明，如果太阳经证未解，必须以从太阳经解表为主。如果表证未解，医生误用泻下法，导致病邪转入阳明，此时适宜攻下，方用小承气汤。如果因误用泻下法而形成结胸证，先服用小陷胸汤，如果病情未好转，再服用大陷胸汤。余邪未尽时，投以枳实理中丸，即可应手而愈。
对于少阳阳明，脉象纯弦的，称为“负”。“负”意味着胜负难料，属于难治之症。如果少阳证较多，必须先从少阳经进行和解治疗，方用小柴胡汤。如果出现腹部胀满、坚硬疼痛、大便不通、说胡话的症状，则需攻下，方用大柴胡汤。
对于正阳阳明，病邪在表的，用葛根汤。表邪入里，但尚未结聚成实的，用白虎汤。邪气已入腑，结聚成实证的，需攻下，方用调胃承气汤。凡是使用下药，必须以腹部胀满、坚硬疼痛、大便不通为主要指征，或者兼见下利肠垢，或下利清稀的黄水，颜色纯青，心下部硬满，说明里面有燥屎，此时方可攻下。否则，即使不大便，也不可攻下，只需清热、润燥即可。
Yangming disease is divided into meridian syndromes and fu-organ syndromes. In Yangming meridian syndrome, symptoms include fever (Fever), headache (Headache), eye pain (Eye pain), nasal dryness (Nasal dryness), chapped lips (Chapped lips), and the desire to rinse the mouth without swallowing (Rinsing mouth without swallowing). The appropriate treatment is to release the muscle layer (Release the muscle layer) using Gegen Tang (Kudzu Root Decoction). If Yangming meridian syndrome transmits to the fu-organ, presenting with steaming fever (Steaming fever), spontaneous sweating (Spontaneous sweating), and thirst with a preference for cold drinks (Thirst preferring cold drinks), this represents diffuse heat (Diffuse heat) which can be cleared but not purged; Baihu Jia Renshen Tang (White Tiger Decoction plus Ginseng) is indicated. In Yangming fu-organ syndrome, the pathogenic heat has fully entered the interior, manifesting as tidal fever (Tidal fever), delirium (Delirium), abdominal fullness (Abdominal fullness), and constipation (Constipation). Purging is indicated using Tiaowei Chengqi Tang (Regulating the Stomach and Directing Downward Decoction), as this is consolidated heat (Consolidated heat) which cannot be resolved by clearing alone.
If Chengqi-type formulas are indicated but only Baihu Tang is used, the consolidated heat will not be eliminated. Conversely, if Baihu Tang is indicated but Chengqi formulas are hastily used, the diffuse pathogen may re-aggregate into a consolidated heat syndrome. Although Shigao (Gypsum Fibrosum) and Dahuang (Rhei Radix et Rhizoma) are both cooling agents, improper use can determine success or failure, let alone the use of herbs with opposing cold and hot properties. Thus, it is indeed difficult for physicians to save lives.
A question arises: The classics state, "There is Taiyang-Yangming, Shaoyang-Yangming, and Zhengyang-Yangming." What does this mean? The answer is: Taiyang-Yangming results from the transmission of the Taiyang meridian to the Yangming fu-organ; Shaoyang-Yangming results from the transmission of the Shaoyang meridian to the Yangming fu-organ; Zhengyang-Yangming results from the direct transmission of the Yangming meridian to its own fu-organ. The general principle is that for Taiyang-Yangming, if the Taiyang syndrome is unresolved, the primary approach must be to release the exterior from the Taiyang level. If the exterior syndrome remains unresolved and the physician mistakenly uses purgation, causing the condition to shift to Yangming, purging is then indicated using Xiao Chengqi Tang (Minor Order the Qi Decoction). If mistreatment with purgation leads to a chest binding syndrome (Chest binding syndrome), Xiaoxianxiong Tang (Minor Sinking-in-the-Chest Decoction) should be administered first; if there is no improvement, Da Xianxiong Tang (Major Sinking-in-the-Chest Decoction) follows. For residual pathogens, Zhishi Lizhong Wan (Immature Bitter Orange and Middle-Warming Pill) is given, resulting in immediate recovery.
For Shaoyang-Yangming, a purely wiry pulse (Wiry pulse) is termed "Fu" (Negative/Defeat), indicating a struggle between righteous qi and pathogen, making it difficult to treat. If Shaoyang symptoms predominate, harmonization from the Shaoyang level is prioritized using Xiaochaihu Tang (Minor Bupleurum Decoction). If abdominal fullness, hardness, pain, constipation, and delirium occur, purging is required using Da Chaihu Tang (Major Bupleurum Decoction).
For Zhengyang-Yangming, if the pathogen is at the exterior, Gegen Tang (Kudzu Root Decoction) is used. If exterior pathogens have entered the interior but have not yet consolidated, Baihu Tang (White Tiger Decoction) is used. If pathogens have entered the fu-organ and formed consolidation/excess, purging is indicated using Tiaowei Chengqi Tang (Regulating the Stomach and Directing Downward Decoction). When using purgatives, the main indications are abdominal fullness, hardness, pain, and constipation. Alternatively, if accompanied by diarrhea with intestinal mucus, or diarrhea of clear yellow water, or stool that is purely green, along with hardness below the heart (epigastric region), it indicates the presence of dry feces (Dry feces) in the interior, warranting purging. Otherwise, even if there is no bowel movement, purging is contraindicated; one should merely clear heat and moisten dryness.