[General Principle] Zhang Zhongjing said: Someone asked, "How does one contract Yangming disease?" The answer is: After Taiyang disease has been treated with sweating, purging, or promoting urination, body fluids are depleted, the stomach becomes dry, and the condition transforms into Yangming disease. Cases characterized by infrequent bowel movements (not changing clothes), internal excess accumulation, and difficult defecation are named Yangming disease. In Yangming disease, those who can eat are termed to have contracted Wind-Cold (Zhong Feng), while those who cannot eat are termed to have contracted Cold-Wind (Zhong Han).

[Commentary] Yu Chang stated: This uses a question-and-answer format to differentiate the interior symptoms of Yangming Wind-Cold. This belongs to the category of Zheng Yang Yangming (True Yangming) and can be treated with purgative methods.

Wei Litong stated: Yangming disease arises because Taiyang disease was not treated properly. Whether through excessive sweating, purging, or promoting urination, these are all causes leading to Yangming disease. Sweating and promoting urination both deplete the body's fluids. Fluids tend to gather in the stomach; when depleted, the stomach becomes dry, generating interior heat. Once interior heat arises, the wind-cold pathogens on the exterior also transform into heat. Interior heat steams outward, causing spontaneous sweating; as wind-cold transforms into heat, there is aversion to heat on the exterior. The interior and exterior heat merge into one, which is why Taiyang disease transforms into Yangming disease. However, Yangming disease varies in depth, and its symptoms are not uniform. "Infrequent bowel movements" result from the depletion of stomach fluids causing dryness. "Internal excess" results from excessive pathogenic heat in the stomach condensing and forming solid accumulation. "Difficult defecation" occurs when stomach dryness and heat are moderately severe, where stool is present but difficult to pass. Different symptoms require different treatments. Regarding the Chengqi Decoctions, Master Zhang did not explicitly specify their usage; the subtlety lies in the practitioner's discretion.

Regarding the ability or inability to eat in Wind-Cold and Cold-Wind cases, this is indeed related to the digestion of food. However, the heat of Wind pathogens is scattered and deficient, while the heat of Cold pathogens is concentrated and excess; the heat of Wind moves through the Qi level, whereas the heat of Cold adheres to the Blood level. These are also reasons for the difference in eating capacity.

Shen Jin'ao noted: This section on Wind-Cold and Cold-Wind is originally unrelated to constipation. I attach it here merely to explain the causes of Yangming disease regarding the ability or inability to eat.

[General Principle] Zhang Zhongjing said: Those with frequent urination will inevitably have hard stools. Even if there is no bowel movement for ten days and the patient feels no distress, if they feel thirsty and desire water, give them small amounts of water frequently. Treat according to the appropriate method; Wuling San (Five-Ingredient Powder with Poria) is suitable.

[Commentary] Wei Litong stated: This indicates that Taiyang disease has resolved but transformed into Yangming disease. Once Yangming disease sets in, interior heat flourishes, causing urine to become yellow-red and frequent. Interior injury to fluids leads to dry, hard stools. Although there may be no bowel movement for ten days without discomfort, this is because fluids are silently consumed, leaving the intestines dry and constipated, so the patient does not feel pain, yet the injury is profound. "Treating according to the method" implies rescuing the condition using the principles of treating both exterior and interior aspects of Taiyang disease. Wuling San guides water to moisten dryness and resolves Taiyang Wind pathogens. It is indeed a necessary medicine for Yangming disease accompanied by Taiyang syndrome.

[General Principle] Zhang Zhongjing said: If the pulse is floating and rapid, and the patient can eat but has no bowel movement, this is an Excess pattern, named Yang Jie (Yang Knotting). It is expected that the condition will worsen on the seventeenth day.

[Commentary] Shen Jin'ao noted: This passage primarily discusses Yin Jie (Yin Knotting); Yang Jie serves as a contrast. Since Yang Jie is equivalent to Stomach Excess (Wei Jia Shi). Yin Jie belongs to Shaoyin disease, presents without exterior symptoms, and should be treated with warming medicines.

[General Principle] Zhang Zhongjing said: In Shanghan (Cold Damage) disease, if there is no bowel movement for six or seven days, aversion to cold is absent, but there is aversion to heat, headache, and body fever, administer Chengqi Tang (Gut-Purging Decoction).

[Commentary] Shen Jin'ao noted: Constipation appearing shortly after contracting the disease indicates Stomach Excess (Wei Jia Shi), which is why it is classified as Yangming disease.

[General Principle] Zhang Zhongjing said: If there is no bowel movement for six or seven days and one suspects dry fecal matter (Zao Shi), the method to verify this is to administer a small amount of Xiao Chengqi Tang (Minor Gut-Purging Decoction). If, after the decoction enters the abdomen, the patient passes gas (Zhuan Shi Qi), this confirms the presence of dry fecal matter, and purgative therapy can proceed. If the next day there is still no bowel movement, but the pulse becomes faint and choppy (Wei Se), this indicates Spleen Deficiency. This is difficult to treat, and Chengqi Tang should not be administered again.

[Commentary] Wei Litong stated: This passage further elaborates on the symptom of delirium (Chan Yu) in Yangming disease. The causes of delirium are discussed in other passages. When Yangming delirium is present, one must carefully consider harmonizing strategies and determine the appropriate time for purging; rash action is unacceptable. Typically, if by the next day there is still no bowel movement and the pulse changes from slippery-rapid to faint-choppy, it confirms interior deficiency-cold of the Stomach. This situation cannot be cured by a single purgative dose nor resolved by a single harmonizing attempt. One must slowly tonify the Stomach and gradually generate fluids. Saying it is "difficult to treat" means that quick results are unlikely and it will not be easy to cure. After six or seven days of constipation, although it appears like Stomach Excess, the Stomach is ultimately not truly excess; rather, it is dry Stomach and intestines with impacted hard stool. This dry fecal matter causes significant harm. Therefore, Xiao Chengqi Tang is used for testing.

[General Principle] Zhang Zhongjing said: Following Shanghan disease, if vomiting or purging fails to resolve the condition, and there is no bowel movement for five to six days, extending up to ten or more days, with tidal fever (Chao Re) occurring in the late afternoon (Ri Bu Suo), aversion to cold is absent, and the patient speaks alone as if seeing ghosts. If the condition is severe, the patient may lose recognition of others during episodes, clutch at clothing and bedsheets, feel terrified and restless, exhibit slight panting, and fixed staring eyes. If the pulse is String-taut (Xian), survival is possible; if the pulse is Choppy (Se), death is likely. For milder cases presenting only with fever and delirium, Da Chengqi Tang (Major Gut-Purging Decoction) is the primary treatment. If relief occurs after one dose, stop taking the remaining medicine.

[Commentary] Fang Zhongxing stated: The disease transforms from Taiyang to Yangming. Constipation persisting for five to six days or more, accompanied by the aforementioned symptoms, indicates that Yangming symptoms are fully developed. Pathogenic heat in the Stomach is flourishing, and the disease has formed excess. Urgent purging is required to save Stomach fluids. Otherwise, hesitation and fear will lead to madness and severe illness, which will be difficult to rescue.

[General Principle] Zhang Zhongjing said: If a patient has had no bowel movement for five to six days, experiences periumbilical pain, restlessness, and periodic exacerbations, this is due to the presence of dry fecal matter. After vigorous purging, if there is no bowel movement for six to seven days, and restlessness persists with abdominal fullness and pain, this is also due to dry fecal matter. This occurs because there were previously retained food masses (Su Shi). Da Chengqi Tang is suitable.

[Commentary] Wei Litong stated: These two passages further clarify the differentiation for purging in Yangming disease when dry fecal matter is present. There are cases where purging does not injure healthy Qi. For example, in patients whose condition extends beyond simple Shanghan, if there is constipation for five to six days, periumbilical pain, restlessness, and periodic attacks, regardless of whether Stomach heat has formed excess, the presence of dry fecal matter in the intestines causes turbid Qi to knot in the center, leading to periumbilical pain and upward disturbance causing restlessness. Knowing this is due to dry fecal matter obstruction, one should simply cleanse and purge the dry feces. Dry feces resulting from retained food occur after vigorous purging depletes fluids, causing the retained food to dry out and block the intestines. Purging is also indicated here.

[General Principle] Zhang Zhongjing said: In Shaoyin disease, if after six to seven days there is abdominal fullness and no bowel movement, urgent purging is required. Da Chengqi Tang is suitable.

[Commentary] Ke Qin stated: By the sixth or seventh day, resolution should have occurred. Failure to resolve indicates transformation into Yangming disease, where Zang Qi is excess and cannot return to the Fu organs. Urgent attack is needed, following the principle that "once entered the Fu organs, purging is indicated." Among the Three Yang channels, only Shaoyang lacks Chengqi indications; among the Three Yin channels, only Shaoyin has Chengqi indications.

Yu Chang stated: Abdominal fullness and constipation after six to seven days indicate excessive Stomach Earth failing to receive nourishment from insufficient Kidney Water, leading to imminent collapse. This differs from the favorable prognosis of Shaoyin where the pulse is weak compared to the Foot-Yang pulse. Purging at this stage is already late; how can one not act urgently?

Wei Litong stated: After six to seven days, pathogenic heat permeates and scorches the Middle Jiao. Not only is Shaoyin Water dried up, but Yangming fluids are also lost. Abdominal fullness indicates Spleen Yin has dispersed, and constipation indicates the intestines and stomach are dry. The situation is critically dangerous. Urgently purging the pathogenic heat saves Kidney Yin. Saving Kidney Yin is saving Stomach and Spleen Yin. Generally, Da Chengqi Tang is used either to break firm accumulations or to penetrate deep-seated pathogens, with the common goal of eliminating heat and preserving True Yin. In Yangming disease, heat consumes Stomach fluids, which are the True Yin of the Stomach; urgent purging saves fluids to save the Stomach. In Shaoyin disease, heat consumes Kidney Water, which is the True Yin of the Kidney; urgent purging saves water to save the Kidney. The method is identical. Understanding this clarifies why Yu Chang stated that Shanghan requires saving Yin; this is precisely where such principles apply.

[General Principle] Zhang Zhongjing said: If a patient has neither exterior nor interior symptoms but has had fever for seven to eight days, even if the pulse is floating and rapid, purging may be indicated. If purging has already been performed but the rapid pulse persists, combined heat will cause rapid digestion and hunger. If after six to seven days there is no bowel movement, this indicates blood stasis (Yu Xue). Dihuang Tang (Dihuang Decoction, typically referring to Didang Tang in this context) is suitable. If the rapid pulse persists and diarrhea continues unceasingly, heat and dampness will combine to cause pus and blood in the stool.

[Commentary] Wei Litong stated: Although there are no Taiyang exterior or Yangming interior symptoms, fever and rapid pulse indicate heat in the interior damaging interior structures. Waiting until fluids are exhausted before purging would be futile; hence, purging is indicated. However, when heat enters the interior without forming Stomach excess, it often descends to the Lower Jiao Blood Chamber, mixing with blood. When blood stasis is severe, even purging will not prevent blood from re-accumulating. When blood heat is severe, purging may result in persistent diarrhea mixed with blood. In such cases, treatment must follow the specific symptoms. Thus, Master Zhang established two post-purging protocols.

[General Principle] Zhang Zhongjing said: In Yangming disease, if there is hardness and fullness under the ribs, constipation, vomiting, and a white coating on the tongue, Xiao Chaihu Tang (Minor Bupleurum Decoction) may be administered. Once the Upper Jiao is unblocked and fluids descend, Stomach Qi harmonizes, and the patient sweats slightly, the disease resolves.

[Commentary] Wei Litong stated: This passage describes a case where Yangming Stomach excess has formed, but pathogens have transferred to Shaoyang. Among the symptoms, only constipation represents true Yangming disease; the others are symptoms expected in Shaoyang-Yangming combinations. However, this represents a transition phase that has not yet fully become Shaoyang disease.