咳之一证。在寻常感冒。由风邪袭于皮毛。内合于肺。其证但鼻塞声重而不发热。人多
目为
伤风轻症。而忽视之。不以为意。然致咳之因。已有寒热内外之不同矣。若发热而咳。其病
亦有传变。正不以咳为肺疾。概从肺经论治也。
太阳病表证不解与寒饮相合。因而致咳者。经云。伤寒表不解。心下有水气。干呕发热
而咳
者。小青龙汤主之。盖内外合寒。非温不解。方用麻黄桂枝。所以去外寒也。半夏干姜。所
以去内寒也。而佐以芍药五味以收肺气之逆。此纯温之剂也。至于肺胀咳而上气。烦躁而
喘。脉浮者。即用本方加石膏。盖其肺气已热。而中挟寒饮。上凌及肺。故不废麻桂之辛
温。而加石膏以降肺金清肃之气。使水从下趋。此热因寒用。又非纯温所宜矣。若阳明热甚
。
火来乘金。因热致咳者。不但误与麻桂。变证不小。即半夏之辛温亦所不宜。当遵仲景法以
栝蒌根易半夏。而欲折阳明之热。舍石膏又谁与归。
其有自表入里。转属少阳者。经云。伤寒中风。往来寒热。胸胁苦满。默默不欲饮食。
心烦
喜呕或咳者。小柴胡去人参大枣生姜加干姜五味子主之。盖小柴胡汤之用半夏。乃逐饮之圣
药
。又有柴胡黄芩以和在表之邪。复用干姜五味以收肺气之逆。且有黄芩而干姜不嫌于过温。
有半夏而五味亦不嫌于过敛也。少阴为水脏。全赖君火以化气。故与太阳相表里。其有阳邪
陷入阴中而咳者。如经云。少阴病四逆。其人或咳者。四逆散加干姜五味子汤主之。盖阳陷
入阴。其人四逆。用柴胡以启其生阳。干姜五味化饮平逆。此乃和剂而非温剂也。若少阴君
火自病者。如经云。少阴病下利六七日。咳而呕渴。心烦不得眠。猪苓汤主之。此已从阳热
化气。其下利乃阳热下利。以猪苓汤分调水道。则烦渴平而咳利均止矣。凡此皆不宜纯温之
证。其宜急温者。则如经云。少阴病腹痛。小便不利。四肢沉重。疼痛自下利者。此为有水
气。其人或咳者。真武汤加五味子细辛干姜主之。此则少阳本藏虚寒之病。阳衰阴盛。当急
温而无疑矣。
咳嗽这一证候，在普通的感冒中，是由风邪侵袭皮毛，内合于肺所致。其症状仅仅是鼻塞、声音沉重而不发热，人们多认为这是伤风的轻症而忽视它，不把它当回事。然而导致咳嗽的原因，已经有寒热内外之不同。如果发热且咳嗽，病情也有传变，并不仅仅因为咳嗽就是肺部的疾病，一概从肺经论治。
太阳病表证未解，与寒饮相合，因而导致咳嗽的，医经说：“伤寒表不解，心下有水气，干呕发热而咳者”，用小青龙汤主治。这是因为内外合寒，非温药不能解散。方中使用麻黄、桂枝，是用来去除外寒；半夏、干姜，是用来去除内寒；并佐以芍药、五味子来收敛上逆的肺气。这是纯温性的方剂。至于肺胀，咳嗽且气逆，烦躁而喘，脉浮的，就用本方加石膏。这是因为肺气已热，而中间夹杂寒饮，上凌于肺，所以不废弃麻黄、桂枝的辛温，而加入石膏以降肺金清肃之气，使水液向下趋行。这是“热因寒用”的方法，又不适宜纯温性的药物了。如果是阳明热盛，火来乘克肺金，因热导致咳嗽的，不但误用麻黄、桂枝，会导致严重的变证，即使半夏的辛温也不适宜。应当遵循张仲景的法度，用栝蒌根代替半夏，而要折除阳明的热邪，除了石膏又能归依谁呢？
那些由表入里，转属少阳的，医经说：“伤寒中风，往来寒热，胸胁苦满，默默不欲饮食，心烦喜呕或咳者”，用小柴胡汤去人参、大枣、生姜，加干姜、五味子主治。盖小柴胡汤中使用半夏，是逐饮的圣药；又有柴胡、黄芩来和解在表的邪气；复用干姜、五味子来收敛上逆的肺气；且有黄芩存在，就不嫌干姜过于温燥；有半夏存在，也不嫌五味子过于收敛。少阴是水脏，完全依赖君火来化气，所以与太阳相表里。如果有阳邪陷入阴中而导致咳嗽的，如医经说：“少阴病四逆，其人或咳者”，用四逆散加干姜、五味子汤主治。这是因为阳气陷入阴中，其人四肢厥冷，用柴胡来激发生发之阳气，干姜、五味子化饮平逆。这是和剂而非温剂。如果是少阴君火自病，如医经说：“少阴病下利六七日，咳而呕渴，心烦不得眠”，用猪苓汤主治。这已经从阳热化气，其下利乃是阳热下利，用猪苓汤分调水道，那么烦渴平息而咳嗽下利都停止了。以上这些都不适宜纯温性的治疗。那些适宜急温的，则如医经说：“少阴病腹痛，小便不利，四肢沉重，疼痛自下利者”，这是有水气，其人如果咳嗽，用真武汤加五味子、细辛、干姜主治。这则是少阴本脏虚寒的病证，阳衰阴盛，应当急温无疑了。
The syndrome of cough, in ordinary common colds, arises when wind pathogen attacks the skin and hair, internally combining with the Lung. The symptoms are merely nasal congestion and a heavy voice without fever. People often regard this as a mild form of wind injury and neglect it, paying no attention to it. However, the causes leading to cough already differ regarding cold/heat and interior/exterior. If there is fever accompanied by cough, the disease also undergoes transmission; one should not simply assume that cough is a lung disease and treat it exclusively from the perspective of the Lung meridian.
When the exterior syndrome of Taiyang disease is unresolved and combines with cold-fluid retention, thereby causing cough, the classic text states: "In cold damage, if the exterior is not resolved, there is water qi beneath the heart; for those with dry heaving, fever, and cough," Xiao Qing Long Tang (Minor Blue Dragon Decoction) is the primary treatment. This is because exterior and interior cold combine, which cannot be resolved without warming agents. The formula uses Mahuang (Ephedrae Herba) and Guizhi (Cinnamon Twig) to dispel exterior cold; Banxia (Pinelliae Rhizoma) and Ganjiang (Zingiberis Rhizoma) to dispel interior cold; assisted by Shaoyao (Paeoniae Radix Alba) and Wuweizi (Schisandrae Fructus) to restrain the rebellious Qi of the Lung. This is a purely warming formula. As for Lung distension, characterized by cough and rebellious Qi, irritability, wheezing, and a floating pulse, the same formula is used with Shigao (Gypsum Fibrosum) added. This is because the Lung Qi has become hot, while cold-fluid retention lingers within, overwhelming the Lung. Therefore, the acrid-warm nature of Mahuang and Guizhi is not abandoned, but Shigao is added to descend the Lung Metal's clear and descending Qi, guiding water downward. This employs the method of "treating heat with cold" (using cold herbs in a warm context or vice versa depending on interpretation, here referring to balancing heat with cold properties), and is no longer suitable for a purely warming approach. If Yangming heat is severe, with Fire overacting on Metal (Lung), causing cough due to heat, not only would the misuse of Mahuang and Guizhi lead to significant adverse transformations, but even the acrid-warm nature of Banxia is unsuitable. One should follow Zhang Zhongjing's method, replacing Banxia with Gualougen (Trichosanthis Radix), and to subdue Yangming heat, who else but Shigao can be relied upon?
For cases transferring from the exterior to the interior, belonging to Shaoyang, the classic text states: "In cold damage or wind strike, with alternating chills and fever, fullness and distress in the chest and hypochondrium, silent desire not to eat, mental irritability, frequent vomiting, or cough," Xiao Chai Hu Tang (Minor Bupleurum Decoction) is modified by removing Renshen (Codonopsis Radix/Panax Ginseng), Dazao (Jujubae Fructus), and Shengjiang (Zingiberis Rhizoma Recens), adding Ganjiang (Zingiberis Rhizoma) and Wuweizi (Schisandrae Fructus). The use of Banxia in Xiao Chai Hu Tang is a sacred medicine for driving out fluid retention. Additionally, Chaihu (Bupleuri Radix) and Huangqin (Scutellariae Radix) harmonize the pathogen at the exterior; Ganjiang and Wuweizi are reused to restrain rebellious Lung Qi. With Huangqin present, Ganjiang is not considered too warming; with Banxia present, Wuweizi is not considered too astringent. Shaoyin is the Water organ, relying entirely on Ministerial Fire to transform Qi, thus having an exterior-interior relationship with Taiyang. If Yang pathogen sinks into Yin causing cough, as stated in the classic: "In Shaoyin disease with cold extremities, if there is occasional cough," Si Ni San (Frigid Extremities Powder) modified with Ganjiang and Wuweizi is used. This is because Yang Qi has sunk into Yin, causing cold extremities; Chaihu is used to stimulate the generating Yang, while Ganjiang and Wuweizi transform fluid retention and calm rebellion. This is a harmonizing formula, not a warming one. If the Ministerial Fire of Shaoyin is diseased itself, as stated: "In Shaoyin disease with diarrhea for six or seven days, cough, vomiting, thirst, mental irritability, and inability to sleep," Zhu Ling Tang (Polyporus Decoction) is used. This has transformed into Yang-heat Qi; the diarrhea is Yang-heat diarrhea. By using Zhu Ling Tang to separate and regulate the water passages, irritability and thirst subside, and both cough and diarrhea cease. All these above are syndromes unsuitable for purely warming treatments. Those requiring urgent warming are like the case stated: "In Shaoyin disease with abdominal pain, difficulty in urination, heaviness and pain in the four limbs, and spontaneous diarrhea," this indicates water qi retention. If there is cough, Zhen Wu Tang (True Warrior Decoction) modified with Wuweizi, Xixin (Asari Radix et Rhizoma), and Ganjiang is used. This is a deficiency-cold syndrome of the Shaoyin organ itself, with Yang decline and Yin excess, requiring urgent warming without doubt.