一 伤寒头疼又身热，便是阳证，不可服热药。
伤寒传三阴、三阳共六经。内太阴病头不疼身不热，少阴病有反发热而无头疼，厥阴病
有头疼而无发热，即是阳证，若医者妄投热药，决致死亡。
一 伤寒当直攻毒瓦斯，不可补益。
邪气在经络中，若随证攻之，三、四日痊安。医者必谓生须正气，却行补益，使毒瓦斯流
炽，必多致杀人。
一 伤寒不思饮食，不可服温脾胃药。
伤寒不思饮食，自是常事，终无饿死之理。如理中丸之类，不可轻服。若阳病服之，
致热气增重，或至不救。
一 伤寒腹痛亦有热证，不可轻服温暖药。
《难经》云∶“痛为实。”故仲景论腹满时痛之证，有曰痛甚者加大黄。夫痛甚而反加
大黄，意可见也。唯身冷厥逆而腹痛者，是阴证，须消息。每见医者，多缘腹痛便投热药而
杀人。
一 伤寒自利，当看阴、阳证，不可例服补药及止泻药。
自利，惟身不热手足温者属太阴，身冷四逆者属少阴、厥阴外，其余身热下利，皆是阳
证，当随证依仲景法治之。每见医者，多缘下利便投暖药及止泻药而杀人。
一 伤寒胸胁痛及腹痛，不可妄用艾灸。
常见村落间有此证，无药便用艾灸，多致毒瓦斯随火而盛，膨胀发喘而死。不知胸胁痛自
属少阳，腹胀满自属太阴，此外惟阴证可灸。
一 伤寒手足厥冷，当看阴阳，不可一例作阴证。
治有阳厥，有阴厥，医者少能分辨。阳厥而投热药，杀人速于用刃。盖阳病不至于极热
，不能发厥，仲景所谓∶“热深则厥深”是也。热深而更与热药，宁有复活之理？但看初得
病而身热，至三、四日后，热气已深，大便秘，小便赤，或谵语昏愦，及别有热证，而反发
厥者，必是阳厥也，宜急用承气汤下之。若初得病，身不热，大便不秘，自引衣盖身，或下
利，或小便数，不见热证而厥逆者，即是阴厥也，方可用四逆汤之类。二厥所以使人疑者，
缘其脉皆沉，然阳厥脉沉而弱，又阳厥脉时复，指爪却温，阴厥常冷，此为可别。
一 伤寒病已在里，即不可用药发汗。
伤寒病须看表里，如发热恶寒，则是在表，正宜发汗。如不恶寒反恶热，即是里证，若
医者一例发汗，则所出之汗，不是邪气，皆是真气。邪气未除而真气先涸，死者多矣。又有
半在表、半在里之证，及无表里之证，不惟皆不可下，仍不可汗，当随证治而消息之。
一 伤寒饮水为欲愈，不可令病患姿饮过度。
病患大渴，当为之水，以消热气，故仲景以饮水为欲愈。人见如此说，遂令病者纵饮，
因而为呕、为喘、为咳逆、为下利、为肿、为悸、为水结、为小便不利者，多矣。且如病患
欲饮一碗，只可与半碗饮之，常令不足为喜矣。
一 伤寒病初瘥，不可过饱及劳动，或食羊肉，行房事，与食诸骨汁及饮酒。
病方愈，脾胃尚弱，食而过饱，不能消化，病即再来，谓之食复。病方愈，血气尚虚，
劳动太早，病即再来，谓之劳复。又，伤寒食羊肉、行房事者，并死。食诸骨汁、饮酒者，
再病。
1. Headache accompanied by fever in Shanghan (Cold Damage) indicates a Yang syndrome; hot-natured medicines must not be administered.
Shanghan pathogens transmit through the Three Yin and Three Yang meridians, involving six channels in total. In Taiyin disease, there is no headache and no fever; in Shaoyin disease, there may be counterintuitive fever without headache; in Jueyin disease, there may be headache without fever. If these are mistaken for Yang syndromes and physicians recklessly administer hot-natured medicines, death will inevitably result.
2. Treatment of Shanghan should directly attack the pathogenic toxins; tonification must not be used.
When pathogenic qi resides in the collaterals and meridians, direct attack according to the syndrome can lead to recovery within three or four days. However, physicians often assume that vital qi (Zheng Qi) needs strengthening and thus employ tonification methods. This causes the pathogenic toxins to become more intense, inevitably leading to many deaths.
3. Loss of appetite in Shanghan does not warrant the use of warm-spleen-stomach tonifying medicines.
Loss of appetite is common in Shanghan and will not lead to death from starvation. Formulas such as Lizhong Wan (Regulate the Middle Pill) should not be taken lightly. If administered to patients with Yang syndromes, it will exacerbate heat, potentially leading to untreatable conditions.
4. Abdominal pain in Shanghan can also present as a Heat syndrome; warm medicines must not be taken lightly.
The Nan Jing states: "Pain belongs to Excess." Therefore, Zhang Zhongjing, in discussing abdominal fullness with intermittent pain, stated that if pain is severe, Rhubarb (Da Huang) should be added. The fact that Rhubarb is added when pain is severe reveals its intent. Only when the body is cold and limbs are cold with abdominal pain does it constitute a Yin syndrome, requiring careful consideration. It is commonly seen that physicians administer hot medicines due to abdominal pain, resulting in patient death.
5. Spontaneous diarrhea in Shanghan requires differentiation between Yin and Yang syndromes; tonics and antidiarrheal medicines must not be used indiscriminately.
Among spontaneous diarrheas, only those with no fever and warm hands and feet belong to Taiyin; those with cold body and cold limbs belong to Shaoyin or Jueyin. All other cases of diarrhea accompanied by fever are Yang syndromes and should be treated according to Zhang Zhongjing's methods. It is frequently observed that physicians administer warming medicines and antidiarrheals for diarrhea, causing patient death.
6. Chest and hypochondriac pain and abdominal pain in Shanghan should not be treated with moxibustion recklessly.
In rural areas, it is common to see this syndrome treated with moxibustion due to lack of medicine, which often causes pathogenic toxins to flourish with the fire, leading to distension, asthma, and death. They do not realize that chest and hypochondriac pain naturally belongs to Shaoyang, and abdominal fullness naturally belongs to Taiyin; aside from these, only Yin syndromes are suitable for moxibustion.
7. Cold extremities in Shanghan require differentiation of Yin and Yang; they must not all be treated as Yin syndromes.
There are Yang Jue (cold extremities due to Yang pathology) and Yin Jue; few physicians can distinguish them. Administering hot medicines for Yang Jue kills faster than using a blade. Yang syndromes do not reach extreme heat without causing Jue; this is what Zhang Zhongjing meant by "the deeper the heat, the deeper the Jue." If heat is deep and hot medicines are given again, is there any chance of revival? One should look at whether the patient had fever initially; by the third or fourth day, if heat has penetrated deeply, stool is constipated, urine is red, or there is delirium and confusion, along with other heat signs, yet cold extremities appear, it must be Yang Jue. Chengqi Tang (Gastro-Regulating Decoction) should be used urgently to purge. If initially there was no fever, stool is not constipated, the patient prefers covering themselves with clothes, or there is diarrhea or frequent urination, without heat signs but with cold extremities, it is Yin Jue, and Sini Tang (Frigid Extremities Decoction) may be used. The reason these two Jues cause confusion is that both have sinking pulses; however, the pulse in Yang Jue is sinking and weak, sometimes intermittent, while fingers and nails remain warm; in Yin Jue, the limbs are constantly cold. This distinguishes them.
8. Once Shanghan pathogens have entered the interior (Li), sweating-inducing medicines must not be used.
Shanghan requires differentiation of exterior and interior. Fever with aversion to cold indicates an exterior syndrome, where sweating is appropriate. Aversion to heat without aversion to cold indicates an interior syndrome. If physicians indiscriminately induce sweating, the sweat produced is not pathogen but genuine qi (Zhen Qi). With pathogens unremoved and genuine qi depleted first, many die. There are also half-exterior/half-interior syndromes and syndromes without clear exterior/interior distinction; these are unsuitable for purgation or sweating and should be treated carefully according to the syndrome.
9. Drinking water in Shanghan indicates impending recovery; patients must not be allowed to drink excessively.
Extreme thirst requires water to dissipate heat, so Zhang Zhongjing regarded drinking water as a sign of recovery. Seeing this, people allow patients to drink freely, leading to vomiting, asthma, coughing, diarrhea, edema, palpitations, fluid retention, and difficulty urinating. If a patient wants one bowl of water, give only half a bowl; it is better to leave them slightly unsatisfied.
10. After initial recovery from Shanghan, overeating, physical exertion, eating mutton, sexual intercourse, consuming bone broths, and drinking alcohol must be avoided.
When the illness just resolves, the spleen and stomach are still weak; overeating leads to indigestion and recurrence, called "food relapse" (Shi Fu). When the illness just resolves, blood and qi are still deficient; early exertion leads to recurrence, called "labor relapse" (Lao Fu). Furthermore, eating mutton or engaging in sexual intercourse after Shanghan leads to death. Consuming bone broths or alcohol leads to disease recurrence.