夫霍乱之病，为卒病之最者。以人起居无他，挥霍之间，便至变乱，闷绝不救，甚为可
畏，临深履危，不足以谕，有生之流，不可不达其旨趣。盖其病因，涉于内外不内外，三种
具备，而读《伤寒论》者，见有本是霍乱，今是伤寒之说，便谓霍乱即伤寒。殊不知因伤寒
致霍乱，只是外因一证尔。况风暑湿皆有此证，殊不知喜怒忧思，饮食饥饱，皆能致霍乱之
证，故不得不备论。
霍乱者，心腹卒痛，呕吐下利，增寒发热，头痛眩晕。先心痛，则先吐；先腹痛，则先
下；心腹俱痛，吐利并作，甚则转筋，入腹则毙。霍乱恶证，无越于斯。此盖阴阳反戾，清
浊相干，阳气暴升，阴气顿坠，阴阳痞隔，上下奔逸。扶救不先，治之唯宜温暖，更详别三
因，随内外以调之；不尔，则坐视困踣也。
诸恶风恶寒，有汗无汗，重着烦毒，皆外所因。盖伤风则恶风有汗，伤寒则恶寒无汗，
冒湿则重着，伤暑则热烦。此虽常论，挥霍之间，仓卒不辨，遂致错误，乱经反常，为害不
浅，岂止本为霍乱，今是伤寒而已哉，当随外所因治之乃可。
治霍乱吐下，胀满，食不消，心腹痛。
人参 干姜(炮) 白术 甘草(炙，各三两)
上为锉散。每服四大钱，水一盏，煎七分，去滓，食前。远行防霍乱，炼蜜和丸如梧子
大，每服三五十丸；如作散，每服方寸匕，酒调下亦得。若转筋者，加石膏 三两；若脐上
筑者，肾气动也，去术，加桂心四两；肾恶燥，故去术，恐作奔豚，故加桂；吐多者，去术
，加生姜三两；下多者，复用术；悸者，加茯苓二两；渴欲得水，加术，合前成四两半；腹
中痛，加人参，合前成四两半；若寒者，加干姜，合前成四两半；腹满者，去术，加附子。
服药后，食顷，食热粥一杯，微自温覆，勿发揭衣被。哕，则加丁香。吐利止，身体痛不休
者，审其原因，以和解之。如初因伤风用桂枝之类，所谓治有本也。
霍乱这种病，是突发疾病中最严重的。因为人们起居正常，却在顷刻之间发生剧烈变化，导致闷绝不醒甚至死亡，非常可怕，即使形容为“临深渊、履薄冰”也不足以比喻其危险程度，对于有生命的人而言，不能不透彻理解其宗旨和要义。大概它的病因，涉及内因、外因和不内外因这三种因素都具备。读《伤寒论》的人，看到其中有“本是霍乱，今是伤寒”的说法，就认为霍乱就是伤寒。殊不知由伤寒导致霍乱的，只是外因中的一种证候罢了。况且风、暑、湿邪都有这种证候，更不知道喜怒忧思等情志失调，以及饮食饥饱不均，都能导致霍乱的证候，所以不得不详细论述。
霍乱的症状，是心腹突然疼痛，呕吐并伴有腹泻，怕冷发热，头痛眩晕。如果先心痛，就先呕吐；先腹痛，就先腹泻；心腹都痛，则呕吐和腹泻同时发作，严重的会出现转筋（肌肉痉挛），如果邪气入腹则会导致死亡。霍乱的危重证候，没有超过这些情况的。这大概是阴阳之气逆乱，清浊之气相互干扰，阳气突然上升，阴气骤然下降，阴阳痞塞阻隔，上下气机奔逸失控。如果不及时扶正急救，治疗只适宜用温补的方法，再详细辨别三因，根据内外情况来调理；否则，就只能坐视病人困顿跌倒而亡了。
各种恶风、恶寒，有汗或无汗，身体沉重烦闷毒热，都属于外所因。感受风邪则恶风且有汗，感受寒邪则恶寒且无汗，冒受湿邪则身体沉重，感受暑邪则发热烦闷。这虽然是常规的理论，但在霍乱发作的顷刻之间，仓促间难以分辨，于是导致错误，扰乱经络，违背常理，造成的危害不浅，岂止是原本诊断为霍乱，现在误诊为伤寒而已呢？应当根据外所因来治疗才可以。
治疗霍乱引起的呕吐腹泻，腹胀满，食物不消化，心腹疼痛。
人参、干姜（炮制）、白术、甘草（炙，各三两）。
以上药物捣碎成散剂。每次服用四大钱，用水一盏，煎煮至七分，去渣，饭前服用。长途旅行预防霍乱，可用炼蜜和药制成梧桐子大小的丸剂，每次服用三五十丸；如果做成散剂，每次服用一方寸匕，用酒调服也可以。如果出现转筋的，加石膏三两；如果脐上跳动不安的，是肾气动扰的表现，去掉白术，加桂心四两；肾恶燥，所以去掉白术，担心引发奔豚病，所以加桂心；呕吐多的，去掉白术，加生姜三两；腹泻多的，重新使用白术；心悸的，加茯苓二两；口渴想喝水的，增加白术用量，与前药合计成四两半；腹中痛的，增加人参用量，与前药合计成四两半；如果感觉寒冷的，增加干姜用量，与前药合计成四两半；腹部胀满的，去掉白术，加附子。服药后，过一会儿，喝一杯热粥，稍微盖被子保暖，不要掀开衣被。出现呃逆的，加丁香。呕吐腹泻停止后，身体疼痛不止的，仔细审察原因，用和解的方法治疗。如果是起初因伤风引起的，用桂枝汤之类的方剂，这就是所谓治病求本。
Huo Luan (acute vomiting and diarrhea) is the most severe among sudden diseases. Although people's daily life proceeds normally, within a moment of turmoil, drastic changes occur, leading to unconsciousness or even death, which is extremely terrifying. Describing it as "standing on the edge of an abyss" or "treading on thin ice" is insufficient to convey its danger. For those who are alive, it is imperative to thoroughly understand its principles and essence. Generally, its etiology involves all three categories: internal causes, external causes, and neither-internal-nor-external causes. Readers of Shanghan Lun (Treatise on Cold Damage) see the statement "originally Huo Luan, now Shanghan," and mistakenly conclude that Huo Luan is identical to Shanghan. They fail to realize that when Huo Luan results from Shanghan, it is merely one manifestation of external causes. Furthermore, wind, summerheat, and dampness pathogens can all present with such symptoms. Moreover, they do not know that emotional disturbances such as anger, joy, worry, and anxiety, as well as dietary irregularities like hunger and overeating, can all induce Huo Luan syndromes. Therefore, a detailed discussion is necessary.
The symptoms of Huo Luan include sudden pain in the heart and abdomen, vomiting accompanied by diarrhea, aversion to cold with fever, headache, and dizziness. If heart pain occurs first, vomiting precedes; if abdominal pain occurs first, diarrhea precedes; if both heart and abdomen hurt, vomiting and diarrhea occur simultaneously. In severe cases, muscle spasms (Zhuan Jin) may appear, and if the pathogen enters the interior, it leads to death. The critical syndromes of Huo Luan do not exceed these manifestations. This is essentially due to the reversal of Yin and Yang Qi, where clear and turbid Qi interfere with each other. Yang Qi rises suddenly, while Yin Qi drops abruptly, causing blockage between Yin and Yang and chaotic movement of Qi above and below. If supportive rescue is not administered promptly, treatment should primarily focus on warming and tonifying, followed by a detailed differentiation of the Three Causes for regulation based on internal or external factors; otherwise, one can only watch helplessly as the patient collapses and perishes.
Various symptoms such as aversion to wind, aversion to cold, presence or absence of sweating, heavy sensation, and irritability with toxic heat belong to external causes. Contracting wind leads to aversion to wind with sweating; contracting cold leads to aversion to cold without sweating; exposure to dampness leads to heaviness; contracting summerheat leads to fever and irritability. Although this is conventional theory, during the sudden onset of Huo Luan, hasty differentiation often leads to errors, disrupting meridians and violating normal patterns, causing significant harm. It is not merely a case of misdiagnosing Huo Luan as Shanghan. Treatment must be guided by the specific external cause.
To treat Huo Luan with vomiting and diarrhea, abdominal distension, indigestion, and heart/abdominal pain:
Ren Shen (Ginseng Radix), Gan Jiang (Zingiberis Rhizoma Preparatum, processed), Bai Zhu (Atractylodis Macrocephalae Rhizoma), Zhi Gan Cao (Glycyrrhizae Radix et Rhizoma Preparatum, honey-fried), each 3 liang.
Grind the above herbs into a coarse powder. Take 4 qian per dose, add 1 zhen of water, decoct until reduced to 0.7 zhen, strain, and take before meals. For prevention of Huo Luan during long journeys, mix the powder with refined honey to form pills the size of wu zi (Chinese quince seeds). Take 30–50 pills per dose. Alternatively, if taken as a powder, use 1 fang cun bi (a square-inch measure) per dose, mixed with wine. If muscle spasms (Zhuan Jin) occur, add Shi Gao (Gypsum Fibrosum) 3 liang. If there is a pulsating sensation above the navel, indicating Kidney Qi moving, remove Bai Zhu and add Gui Xin (Cinnamomi Cortex) 4 liang. Since the Kidney dislikes dryness, Bai Zhu is removed to prevent triggering Ben Tun (fleeing tumor); thus, Gui Xin is added. If vomiting is predominant, remove Bai Zhu and add Sheng Jiang (Zingiberis Rhizoma Recens) 3 liang. If diarrhea is predominant, retain Bai Zhu. If palpitations occur, add Fu Ling (Poria) 2 liang. If thirsty and desiring water, increase Bai Zhu so that the total amount becomes 4.5 liang. If abdominal pain occurs, increase Ren Shen so that the total amount becomes 4.5 liang. If feeling cold, increase Gan Jiang so that the total amount becomes 4.5 liang. If abdominal fullness occurs, remove Bai Zhu and add Fu Zi (Aconiti Lateralis Radix Preparata). After taking the medicine, wait a short while, then drink a cup of hot porridge, cover slightly to maintain warmth, but do not expose oneself to drafts. If hiccups (Yue) occur, add Ding Xiang (Caryophylli Flos). If vomiting and diarrhea cease but body pain persists, carefully investigate the cause and treat with harmonizing methods. If initially caused by wind injury, use formulas similar to Gui Zhi Tang (Cinnamon Twig Decoction). This is what is meant by treating the root cause.