汗吐攻和。为治杂病四大法。而失血之证。则有宜不宜。伤寒过汗伤津液。吐血既伤阴血。又伤水津。则水
血两伤。HT 然枯骨矣。故仲景于衄家严戒发汗。衄忌发汗。吐咯可知矣。夫脉潜气伏。斯血不升。发汗则气
发泄。吐血之人。气最难敛。发泄不已。血随气溢。而不可遏抑。故虽有表证。止宜和散。不得径用麻桂羌独。
果系因外感失血者。乃可从外表散。然亦须敛散两施。毋令过汗亡阴。盖必知血家忌汗。然后可商取汗
之法。至于吐法。尤为严禁。失血之人。气既上逆。若见有痰涎。而复吐之。是助其逆势。必气上不止矣。治病
之法。上者抑之。必使气不上奔。斯血不上溢。降其肺气。顺其胃气。纳其肾气。气下则血下。血止而气亦平
复。血家最忌是动气。不但病时忌吐。即已愈后。另有杂证。亦不得轻用吐药。往往因吐便发血证。知血证
忌吐。则知降气止吐。便是治血之法。或问血证多虚。汗吐且有不可。则攻下更当忌矣。予曰不然。血之所
以上者。以其气腾溢也。故忌吐汗。再动其气。至于下法。乃所以折其气者。血证气盛火旺者。十居八九。当
其腾溢。而不可遏。正宜下之以折其势。仲景阳明证。有急下以存阴法。少阴证。有急下以存阴法。血证火
气太盛者。最恐亡阴。下之正是救阴。攻之不啻补之矣。特下之须乘其时。如实邪久留。正气已不复支。或
大便溏泻。则英雄无用武之地。只可缓缓调停。纯用清润降利。以不违下之意。斯得法矣。至于和法。则为
血证之第一良法。表则和其肺气。里者和其肝气。而尤照顾脾肾之气。或补阴以和阳。或损阳以和阴。或
逐瘀以和血。或泻水以和气。或补泻兼施。或寒热互用。许多妙义。未能尽举。四法之外。又有补法。血家属
虚痨门。未有不议补者也。即病家亦喜言补。诸书重补者。尤十之八九。而不知血证之补法。亦有宜有忌。
如邪气不去而补之。是关门逐贼。瘀血未除而补之。是助贼为殃。当补脾者十之三四。当补肾者十之五
六。补阳者十之二三。补阴者十之八九。古有补气以摄血法。此为气脱者说。非为气逆者说。又有引火归
元法。此为水冷火泛者立说。非为阴虚阳越者立说。盖失血家如火未发。补中则愈。如火已发。则寒凉适
足以伐五脏之生气。温补又足以伤两肾之真阴。惟以甘寒。滋其阴而养其阳血。或归其位耳。血家用药
之宜忌。大率如是。知其大要。而后细阅全书。乃有把握。
汗法、吐法、攻下法和和解法，是治疗杂病的四大法则。但对于失血病症，则有适宜与不适宜之分。伤寒病中，过度发汗会损伤津液；吐血患者既已损伤阴血，又损伤水津，导致水与血两伤，身体便会像干枯的骨头一样枯竭。因此，张仲景对鼻衄（鼻出血）患者严格禁止使用发汗法。既然鼻衄忌讳发汗，那么呕吐和咯血也自然忌讳发汗了。
脉象沉潜、气机伏匿，血液才能正常下行而不妄升。若使用发汗法，会导致气机外泄发散。吐血患者的气机最难收敛，如果继续发散，血液就会随着气机的上逆而溢出，无法遏制抑制。所以，即使有表证，也只宜采用和解疏散的方法，不得直接使用麻黄、桂枝、羌活、独活等峻烈发汗之药。
如果是确实因外感邪气导致的失血，才可以从体表进行疏散，但也必须同时使用收敛与发散相结合的方法，不要让过度发汗导致阴液亡失。只有明白了失血患者忌讳发汗，然后才可以商讨取汗的方法。至于吐法，更是严禁使用的。失血之人，气机已经上逆，如果见到有痰涎，反而使用催吐法，这是助长其气机上逆之势，必然导致气机上冲不止。
治病的原则是：气机上逆者应当压制它，必须使气机不上奔，这样血液才不上溢。通过降肺气、顺胃气、纳肾气，使气机下行，血液随之而下，血液止住后气机也能平复。失血患者最忌讳的是动气。不仅在患病期间忌讳催吐，即使在痊愈后，若有其他杂证，也不得轻易使用吐药。往往因为催吐而引发血证。知道了血证忌讳催吐，就知道降气止吐就是治疗血证的法则。
有人问：血证多属虚证，汗法和吐法尚且不可用，那么攻下法更应当忌讳了吧？我说不是这样的。血液之所以上逆，是因为气机腾涌溢满。所以忌讳吐法和汗法，以免再次扰动气机。至于下法，正是用来折抑气机的方法。血证中气盛火旺的患者，十有八九。当气机腾涌溢满、无法遏制时，正适宜用下法来折抑其势头。张仲景在阳明证中有“急下存阴”的法度，在少阴证中也有“急下存阴”的法度。血证中火气太盛的患者，最担心阴液亡失，使用下法正是为了救阴，攻下不仅不是伤害，反而等同于补益。
但是，使用下法必须把握时机。如果实邪久留体内，正气已经不能支撑，或者大便溏泻，那么攻下法就英雄无用武之地了。这时只可缓缓调理，纯用清凉滋润、降气通利的方法，以不违背下法的本意，这才是得法。至于和法，则是治疗血证的第一良法。在表则调和肺气，在里则调和肝气，并且特别照顾脾肾之气。或补阴以调和阳，或损阳以调和阴，或逐瘀以调和血，或泻水以调和气机，或补泻兼施，或寒热互用，其中的妙义繁多，未能一一列举。
在汗、吐、攻、和四法之外，还有补法。血证属于虚劳门类，没有不讨论补法的。就连病人也喜欢谈论补益，各种医书中重视补法的，尤其占十之八九。然而不知道血证的补法，也有适宜与忌讳之处。如邪气未去而盲目进补，这是“关门逐贼”；瘀血未除而盲目进补，这是“助贼为殃”。应当补脾的占十之三四，应当补肾的占十之五六，补阳的占十之二三，补阴的占十之八九。古代有“补气以摄血”的方法，这是针对气脱而言的，并非针对气逆而言。又有“引火归元”的方法，这是针对水冷火泛而言设立的学说，并非针对阴虚阳越而言设立的学说。大概失血患者如果火气未发，在中焦进补则会痊愈；如果火气已发，则寒凉药足以伐害五脏的生气，温补药又足以损伤两肾的真阴。只有使用甘寒之品，滋养阴液并养护阳血，使其回归本位罢了。血证患者用药的适宜与忌讳，大致如此。掌握了这些大要，然后再细读全书，才会有把握。
Sweating (Diaphoresis), Vomiting (Emesis), Purging (Purgation), and Harmonizing (Harmonization) constitute the four major methods for treating miscellaneous diseases. However, in cases of hemorrhage, there are indications and contraindications. In Shanghan (Cold Damage) disease, excessive sweating damages the body fluids. In hematemesis (vomiting blood), both Yin-blood and water-jin (body fluids) are damaged, leading to a dual deficiency of water and blood, causing the body to wither like dry bones. Therefore, Zhang Zhongjing strictly forbids diaphoresis in patients with epistaxis (nosebleed). If epistaxis contraindicates sweating, then vomiting and hemoptysis (coughing up blood) certainly do as well.
When the pulse is deep and hidden, and Qi is latent, blood descends properly and does not ascend recklessly. Sweating causes Qi to dissipate outward. In patients with hematemesis, Qi is difficult to consolidate; if it continues to dissipate, blood will overflow following the ascending Qi, becoming uncontrollable. Thus, even if exterior symptoms are present, only harmonizing and dispersing methods should be used; one must not directly employ potent diaphoretics such as Ephedrae Herba (Mahuang), Cinnamon Twig (Guizhi), Notopterygii Rhizoma et Radix (Qianghuo), or Saussureae Radix (Duhuo).
If the hemorrhage is indeed caused by external pathogens, dispersion from the exterior may be considered, but it must combine dispersing with consolidating measures to prevent excessive sweating from depleting Yin. Only by understanding that hemorrhagic patients contraindicate sweating can one discuss methods to induce sweat. As for emesis, it is strictly prohibited. Patients with hemorrhage already have rebellious Qi; if phlegm-saliva is present and emesis is induced, this aids the rebellious trend, inevitably causing Qi to ascend without cessation.
The principle of treatment dictates that for upward-rebellious conditions, one must suppress them. By ensuring Qi does not rush upward, blood will not overflow. By descending Lung Qi, smoothing Stomach Qi, and anchoring Kidney Qi, Qi descends, and blood follows. Once bleeding stops, Qi also returns to calmness. Hemorrhagic patients most fear the disturbance of Qi. Not only is emesis contraindicated during illness, but even after recovery, if other miscellaneous syndromes arise, emetic drugs must not be used lightly. Often, emesis triggers hemorrhagic syndromes. Knowing that hemorrhage contraindicates emesis implies that descending Qi and stopping vomiting are methods for treating hemorrhage.
One might ask: Hemorrhagic syndromes are mostly deficient; since sweating and vomiting are inadvisable, purging should certainly be contraindicated. I say otherwise. Blood ascends because Qi surges and overflows. Hence, we contraindicate emesis and sweating to avoid agitating Qi further. Purging, however, is precisely the method to curb Qi. Eight or nine out of ten hemorrhagic cases involve excess Qi and flourishing Fire. When Qi surges uncontrollably, purging is appropriate to curb its momentum. Zhang Zhongjing’s Yangming syndrome protocols include "urgent purging to preserve Yin," and Shaoyin syndrome protocols also include "urgent purging to preserve Yin." In hemorrhagic cases with excessive Fire, the greatest fear is the loss of Yin; purging is exactly the means to save Yin. Purging here is tantamount to tonification.
However, purging must be timed correctly. If pathogenic factors remain long-term and Zheng Qi (Upright Qi) can no longer support, or if loose stools/diarrhea occur, purging has no place. In such cases, one should regulate slowly, using purely cooling, moistening, descending, and draining methods, adhering to the intent of purging without violating it. This constitutes proper technique.
Harmonizing is the premier method for treating hemorrhage. For exterior issues, it harmonizes Lung Qi; for interior issues, it harmonizes Liver Qi, while particularly attending to Spleen and Kidney Qi. It may tonify Yin to harmonize Yang, reduce Yang to harmonize Yin, expel stasis to harmonize Blood, drain water to harmonize Qi, combine tonification and purgation, or use cold and hot herbs mutually. The subtleties are numerous and cannot be fully enumerated.
Beyond these four methods lies tonification. Hemorrhage falls under the category of Deficiency Consumption (Xu Lao); discussion of tonification is inevitable. Even patients prefer talking about tonification, and medical texts emphasize tonification in eight or nine out of ten cases. Yet, one must know that tonification for hemorrhage also has indications and contraindications. Tonifying when pathogenic factors are unremoved is like "locking the door to chase away thieves"; tonifying when blood stasis remains is like "aiding thieves to cause disaster." Tonification of the Spleen applies to 30-40% of cases; tonification of the Kidney applies to 50-60%; tonification of Yang applies to 20-30%; tonification of Yin applies to 80-90%.
Ancient texts mention "tonifying Qi to control Blood," which applies to Qi collapse, not Qi rebellion. There is also the method of "guiding Fire back to its source," established for conditions of Cold Water and Floating Fire, not for Yin deficiency with Yang hyperactivity. Generally, if Fire has not erupted in hemorrhagic patients, tonifying the Middle Jiao leads to recovery. If Fire has erupted, cold-natured herbs suffice to destroy the vital energy of the Five Zang organs, while warm-tonifying herbs damage the True Yin of the two Kidneys. One should instead use sweet-cold herbs to nourish Yin and nurture Yang-Blood, returning them to their proper positions. The indications and contraindications for drug usage in hemorrhagic patients are generally as described above. Grasping these key principles allows for a firm grasp upon detailed study of the entire text.