陈无择《三因方》云∶夫疟备三因，外则感四气，内则动七情，饮食饥饱，房室劳逸，
皆能致之。经所谓夏伤暑，秋咳疟者，此则因时而叙耳，不可专以此论。外所因证，有寒
疟，有温疟，有瘅疟，并同《素问》也。有湿疟者，寒热身重，骨节烦疼，胀满自汗，善呕
，因汗出复浴，湿舍皮肤，及冒雨湿也。有牝疟者，寒多不热，但惨戚振栗，病以时作，此
则多感阴湿，阳不能制阴也。此五种疟疾，以外感风寒暑湿，与卫气相并而成。除瘅疟独热
，温疟先热，牝疟无热外，诸疟皆先寒后热。内所因证，病者以蓄怒伤肝，气郁所致，名曰
肝疟。以喜伤心，心气耗散所致，名曰心疟。以思伤脾，气郁涎结所致，名曰脾疟。以忧伤
肺，肺气凝痰所致，名曰肺疟。以失志伤肾所致，名曰肾疟。所致之证，并同《素问》。此
五种疟疾，以感气不和，郁结痰饮所致。不内外因，有疫疟者，一岁之间，长幼相似也。有
鬼疟者，梦寐不祥，多生恐怖也。有瘴疟者，乍热乍寒，乍有乍无，南方多病也。有胃疟者
，饮食饥饱，伤胃而成，世谓食疟也。有劳疟者，经年不瘥，前后复发，微劳不任也。亦有
数年不瘥，结成 癖在腹胁，名曰老疟，亦曰母疟。以上诸证，各有方治，宜推而用之
。
愚谓疟疾一证，《内经》言已详尽，无可加矣。而后世议论烦多，反资疑贰，兹举陈氏
三因之说，以见其概。如所云湿疟者，因汗出复浴，湿舍皮肤，固一说也。然浴以热汤，避
彼风处，则断不致疟，惟冷水相加，疟斯成矣。若然则仍是寒气，即《内经》所云夏遇凄沧
水寒之证也。然此犹近似，但宜辨明寒热耳。至若牝疟无热，则《内经》并无此说，惟《金
匮要略》曰∶疟多寒者，名曰牝疟，蜀漆散主之，亦非曰无热也。若果全无发热，而止见寒
栗，此自真寒阳虚证耳，别有本门。又安得谓之疟耶？再如内因五脏之疟，在《内经·刺疟
论》所言六经五脏之证，不过为邪在何经之辨，原非谓七情所伤便能成疟，而此云所致之证
，并同《素问》，则《素问》无此说也。且既云七情所伤，则其虚实大有不同，又岂皆痰饮
所致耶？再若不内外因，凡鬼疟梦寐之说，此或以疟邪乱神，因致狂言似鬼者有之，岂鬼崇
果能为疟乎？至若胃疟，既云饮食，则明是内伤，且凡先因于疟而后滞于食者有之，未有不
因外邪而单有食疟者也。夫病情必有标本，标本误认，治岂无瘥？窍计陈氏之言，既以三因
立论，故不得不敷演其说，而烨然若有可观，不知影响之谈，不但无益于病，而且乱人意见
，致令临证狐疑，莫知所从，而每至于害者，皆此之类。
丹溪曰∶疟有暑、有风、有湿、有痰、有食积。久发者，为老疟，不已者，为疟母。风
暑之疟，多因夏月在风凉处歇，遂闭汗不能得泄，暑舍于内。故大法当汗之。疟而恶饮食者
，必从饮食上得之，当以食治。俗云脾寒，乃因名而迷其实也。苟因饮食所伤而得之，未必
是寒，况其他乎。
严用和曰∶或乘凉饮冷，当风卧湿，饥饱失时，致脾胃不和，痰积中脘，遂成此疾，所
谓无痰不成疟也。
张子和曰∶《内经》既以夏伤于暑而为疟，何世医皆以脾寒治之，用姜、附、硫黄之类
，甚者归之祟怪，良可笑也。又或因夏月饮食生冷之类，指为食疟，此又非也。岂知《内经
》之论则不然，皆夏伤于暑，遇秋风寒而后作也。邪热浅则连日，邪热深则间日，并入于里
则寒，并入于表则热，若此论则了不相干于脾也。治平之时，其民夷静，虽用砒石、辰砂有
毒之药，以热治热，亦能取效。扰攘之时，其民劳苦，内火与外火俱动，以热攻热，转为泻
痢、吐血、疮疡、呕吐之疾，岂与夷静之人同治哉。予尝用张长沙汗吐下三法，愈疟病极多
，大忌错作脾寒治之。
愚谓疟疾之作，本由风寒水湿之邪感而致病，亦或有非风非水而衣薄受凉，凡体怯者，
皆能为疟。及其病深，则未免因经及脏，因表及里，故有不慎饮食而更甚者，有不慎劳役而
增病者，总之无非外邪为之本，岂果因食因痰有能成疟者耶？今观朱丹溪之言，亦以痰食并
列，严用和则悉归之痰。盖皆因陈氏之说，而殊失《内经》之正意矣。故张子和亦以祟怪为
笑，以食疟为非，而云治平扰攘时当分治，是皆有理确见也。独怪其以暑为火，而且谓扰攘之
时，其民劳苦，大忌错作脾寒治之，而尝用汗吐下三法。恐此言亦属偏见也。念余幸逢明盛
，固不知扰攘景象，第以劳苦过伤之人，其虚更甚，又岂无三阳疲损等证，而可俱谓之火，
及可尽用三法乎？甚哉立言之难，于此可见，而时中之不易得也如此。
陈无择在《三因方》中说：疟疾具备三种病因，外感则是感受风、寒、暑、湿四气，内伤则是触动喜、怒、忧、思、悲、恐、惊七情，饮食饥饱不均，房事过度或劳逸失度，都能导致此病。医经所说“夏季感受暑邪，秋季咳嗽发作疟疾”，这只是按季节时序叙述而已，不能专门以此作为定论。外感病因所致的证候，有寒疟（以恶寒为主），有温疟（先热后寒），有瘅疟（但热不寒），这些都与《素问》一致。还有湿疟，症状为忽冷忽热、身体沉重、骨节烦痛、胸腹胀满、自汗、容易呕吐，这是因为出汗后洗澡，湿气停留在皮肤，以及冒雨受湿所致。还有牝疟（阴疟），症状为恶寒多而发热少，神情凄惨、战栗，按时发作，这多是感受阴湿之邪，阳气不能制约阴气所致。这五种疟疾，是由外感风、寒、暑、湿，与卫气相搏结而成。除了瘅疟独热、温疟先热、牝疟无热之外，其他疟疾都是先恶寒后发热。内伤病因所致的证候，患者因为郁怒伤肝，气机郁滞所致，名叫肝疟；因为喜乐伤心，心气耗散所致，名叫心疟；因为思虑伤脾，气郁痰涎凝结所致，名叫脾疟；因为忧愁伤肺，肺气凝滞生痰所致，名叫肺疟；因为意志消沉伤肾所致，名叫肾疟。这些证候表现，都与《素问》相同。这五种疟疾，是因为感受气候不和，气机郁结、痰饮内停所致。非内非外因（不内外因）方面，有疫疟，一年内老少都相似地患病；有鬼疟，梦中见不祥之事，多产生恐怖心理；有瘴疟，忽冷忽热，时有时无，多见于南方地区；有胃疟，因为饮食饥饱失常，损伤胃气而成，世人称为食疟；有劳疟，经年不愈，前后复发，轻微劳累便无法承受。也有数年不愈，结成癖块在腹部胁肋，名叫老疟，也叫母疟（疟母）。以上各种证候，各有相应的方药治疗，应当推究其理而使用。
我认为疟疾这一病症，《内经》已经论述得非常详尽，没有什么可以添加的了。而后世议论繁多，反而增加疑惑，这里列举陈氏的三因学说，来展示其大概。像他所说的湿疟，因为出汗后洗澡，湿气停留在皮肤，这固然是其中一种说法。然而如果用热水洗澡，避开风口，就绝不会导致疟疾，只有用冷水洗浴，疟疾才会形成。如果这样，那仍然是寒气，即《内经》所说的夏季遇到清凉水寒的证候。但这还算是近似，只是应当辨明寒热罢了。至于牝疟无热，则《内经》中并没有这种说法，只有《金匮要略》说：“疟疾恶寒多的，名叫牝疟，用蜀漆散主治”，也并不是说完全没有发热。如果真的完全没有发热，只见到寒战，这自然是真寒假阳虚的证候，属于其他门类，又怎么能叫作疟疾呢？再比如内因五脏之疟，在《内经·刺疟论》中所说的六经五脏的证候，不过是为了辨别邪气在哪一经，原本不是说七情所伤就能形成疟疾，而这里说所致证候同于《素问》，那么《素问》中其实没有这种说法。况且既然说是七情所伤，那么虚实差别很大，又哪里全是痰饮所致呢？再说不内外因中，凡是关于鬼疟梦寐的说法，这或许是因为疟邪扰乱心神，导致胡言乱语像见鬼一样，难道鬼神真的能造成疟疾吗？至于胃疟，既然提到饮食，那明显是内伤，而且凡是有先患疟疾然后导致饮食停滞的情况，却没有不因为外邪而单纯由饮食导致疟疾的。病情一定有本和标，如果把标本搞错，治疗怎么可能痊愈？我推测陈氏的话，既然以三因为立论基础，所以不得不铺陈发挥他的理论，看起来似乎很有可观之处，却不知道这是似是而非的言论，不但对疾病无益，而且扰乱人们的见解，导致临证时犹豫不决，不知听从谁，从而往往造成伤害，都是这类情况。
朱丹溪说：疟疾有暑疟、风疟、湿疟、痰疟、食积疟。久发不愈的，叫老疟，不停止的，叫疟母。风暑之疟，多因为在夏天在风凉处休息，导致汗孔闭塞，汗液不能排泄，暑邪留在体内。所以大法应当用发汗法。疟疾如果厌恶饮食，必定是从饮食上得来的，应当用消食导滞的方法治疗。俗话说的“脾寒”，是因为名字而迷惑了其实质。如果是因饮食所伤而得的，未必是寒证，何况其他的呢。
严用和说：或者乘凉饮冷，当风卧湿，饥饱失时，导致脾胃不和，痰积在中脘，于是形成此病，所谓“无痰不成疟”。
张子和说：《内经》既然说夏季伤于暑而得疟，为什么后世医生都用治脾寒的方法，使用干姜、附子、硫黄之类的药物，严重的甚至归结为鬼神作祟，真是可笑啊。又有人因为夏季饮食生冷之类，指为食疟，这也不对。哪里知道《内经》的论述却不是这样，都是夏季伤于暑，遇到秋风寒冷后才发作。邪热浅则连日发作，邪热深则间日发作，邪气并入于里则恶寒，并入于表则发热，像这样的论述，完全与脾无关。在太平时期，百姓安宁平静，即使使用砒石、辰砂等有毒的药物，以热治热，也能取得疗效。在动乱时期，百姓劳苦，内火与外火同时发动，以热攻热，反而转为泻痢、吐血、疮疡、呕吐等疾病，怎么能与安宁时期的人同样治疗呢？我曾经用张仲景的汗、吐、下三法，治愈了很多疟疾病人，最忌讳错误地当作脾寒来治疗。
我认为疟疾的发生，本来是由风、寒、水、湿之邪感应而致病，也有不是风不是水而是衣服单薄受凉，凡是体质虚弱的人，都能导致疟疾。等到病深入，就难免涉及经络和脏腑，由表及里，所以有不慎饮食而加重的，有不慎劳累而增病的，总之无非是外邪为本，难道真的是因为饮食、因为痰饮就能形成疟疾吗？现在看朱丹溪的话，也是把痰和食并列，严用和则全部归咎于痰。这都是因为陈氏的说法，而大大失去了《内经》的正意。所以张子和也以鬼神作祟为笑谈，认为食疟不对，并且说太平和动乱时期应当分别治疗，这些都是有理有据的见解。唯独奇怪他把暑当作火，而且说动乱时期百姓劳苦，最忌讳错误地当作脾寒治疗，并且曾经使用汗、吐、下三法。恐怕这些话也属于偏见吧。我想我幸好逢到清明盛世，不知道动乱的景象，但对于那些因劳苦过度而受伤的人，他们的虚损更严重，难道没有三阳经疲损等证候，而都可以说是火证，并且可以全部使用汗、吐、下三法吗？发表言论的困难，从这里就可以看出，而要掌握中庸之道、恰到好处地治疗是如此不易啊。
Chen Wuyue stated in *San Yin Fang* (Three Causes): Malaria involves three categories of causes. Externally, it is caused by contracting the four climatic pathogens: wind, cold, summerheat, and dampness. Internally, it is triggered by the seven emotions. Irregularities in diet (such as hunger or overeating), excessive sexual activity, or imbalance between work and rest can all lead to this disease. The classic texts mention "summer injury by summerheat leading to autumn malaria," which is merely a description based on seasonal timing and should not be taken as the sole explanation. Regarding external causes, there are Cold Malaria (characterized by predominant chills), Warm Malaria (predominant heat followed by chills), and Dan Malaria (pure heat without chills), consistent with the *Su Wen*. There is also Damp Malaria, characterized by alternating chills and fever, heaviness of the body, painful joints, abdominal distension, spontaneous sweating, and frequent vomiting. This occurs when bathing after sweating allows dampness to lodge in the skin, or from exposure to rain and dampness. There is also Pin Malaria (Yin Malaria), characterized by severe chills with little or no fever, accompanied by a miserable demeanor and tremors occurring at specific times. This is often due to contracting yin-damp pathogens, where yang qi fails to control yin. These five types of malaria result from external contraction of wind, cold, summerheat, and dampness combining with defensive qi (Wei Qi). Except for Dan Malaria (pure heat), Warm Malaria (heat precedes chills), and Pin Malaria (no heat), most malarial cases present with chills preceding fever.
Regarding internal causes, if a patient suffers liver injury from suppressed anger, causing qi stagnation, it is named Liver Malaria. If joy injures the heart, causing dispersion of heart qi, it is named Heart Malaria. If excessive thinking injures the spleen, causing qi stagnation and phlegm-fluid retention, it is named Spleen Malaria. If sorrow injures the lungs, causing lung qi stagnation and phlegm formation, it is named Lung Malaria. If loss of will injures the kidneys, it is named Kidney Malaria. These manifestations align with the *Su Wen*. These five types arise from climatic disharmony, qi stagnation, and phlegm-fluid retention.
Regarding non-internal/non-external causes, there is Epidemic Malaria, affecting people of all ages similarly within a year; Ghost Malaria, involving ominous dreams and intense fear; Zang Malaria, characterized by intermittent chills and fever, common in southern regions; Stomach Malaria, caused by dietary irregularities damaging stomach qi, commonly known as Food Malaria; and Labor Malaria, which persists for years, recurs, and cannot withstand even slight exertion. If it persists for years and forms a mass in the abdomen or hypochondrium, it is called Old Malaria or Mother Malaria (Malaria Mass). Each of these conditions has specific treatments that should be applied after careful deduction.
I believe that regarding malaria, the *Nei Jing* (Inner Canon) has already provided exhaustive explanations, leaving nothing to add. Later discussions have become overly complex, creating confusion. I cite Chen’s theory of the Three Causes to illustrate its general outline. For instance, his claim that Damp Malaria results from bathing while sweaty, allowing dampness to lodge in the skin, is one perspective. However, if one bathes with hot water and avoids drafts, malaria would not occur; it only happens with cold water. Thus, this is still essentially cold pathogen, akin to the *Nei Jing*'s description of encountering cold water in summer. While plausible, one must distinguish between cold and heat. Furthermore, the concept of Pin Malaria having no heat is absent from the *Nei Jing*. The *Jin Gui Yao Lue* states, "Malaria with predominant chills is called Pin Malaria, treated with Shuqi San," but does not claim absence of heat. If there is absolutely no fever, only chills, this indicates true cold and yang deficiency, belonging to a different category, and cannot be classified as malaria.
Regarding the Five Zang Malarial syndromes, the *Ci Ma Lun* chapter in the *Nei Jing* discusses six meridians and five zang organs to identify the location of the pathogen, not to suggest that emotional injuries directly cause malaria. Claiming these match the *Su Wen* is inaccurate, as the *Su Wen* does not state this. Moreover, since emotional injuries vary greatly in excess and deficiency, they cannot all be attributed to phlegm-fluid retention. As for Ghost Malaria, perhaps malaria pathogens disturb the spirit, causing delirium resembling hallucinations, but ghosts do not literally cause malaria. Regarding Stomach Malaria, although linked to diet, it is clearly an internal injury. While malaria can lead to food stagnation, there is no case of food alone causing malaria without external pathogens. Disease always has a root (ben) and branch (biao); misidentifying them leads to treatment failure. Chen’s elaboration on the Three Causes appears impressive but is likely speculative. Such vague theories not only fail to help patients but also confuse clinicians, leading to hesitation and harm.
Zhu Danxi stated: Malaria can be caused by summerheat, wind, dampness, phlegm, or food stagnation. Persistent malaria is called Old Malaria; if it forms a mass, it is called Mother Malaria. Wind-summerheat malaria often results from resting in cool, breezy places during summer, closing the pores and preventing sweat excretion, trapping summerheat internally. Therefore, the primary treatment is diaphoresis (sweating method). If malaria is accompanied by aversion to food, it stems from dietary issues and should be treated by regulating digestion. The folk term "Spleen Cold" confuses the name with the actual pathology. Even if caused by dietary injury, it is not necessarily cold, let alone other causes.
Yan Yonghe said: Exposure to cold, drinking chilled liquids, lying in dampness, or irregular eating habits can disrupt spleen and stomach harmony, causing phlegm accumulation in the middle jiao, resulting in this disease. Hence the saying, "No phlegm, no malaria."
Zhang Zihe argued: Since the *Nei Jing* attributes malaria to summerheat injury in summer, why do later physicians treat it as Spleen Cold using warming herbs like dried ginger, prepared aconite, and sulfur? Some even attribute it to demonic influence, which is ridiculous. Others blame summer consumption of raw/cold foods, calling it Food Malaria, which is also incorrect. The *Nei Jing* teaches that summerheat injury combined with autumn wind-cold triggers the disease. Shallow heat causes daily attacks; deep heat causes every-other-day attacks. Pathogens entering the interior cause chills; those in the exterior cause fever. This mechanism has nothing to do with the spleen. In peaceful times, when people are calm, toxic herbs like realgar and cinnabar used in hot-to-treat-hot methods can be effective. In turbulent times, when people are exhausted and internal/external fire are active, using heat to attack heat may cause dysentery, hematemesis, sores, or vomiting. Treatment must differ based on the context. I have successfully treated many malaria cases using Zhang Zhongjing’s methods of inducing sweating, vomiting, and purgation, strictly avoiding treating it as Spleen Cold.
I maintain that malaria originates from external pathogens like wind, cold, water, and dampness. Even thin clothing causing chill in weak constitutions can trigger it. As the disease deepens, it affects meridians and zang organs, moving from exterior to interior. Neglecting diet or labor can exacerbate it. Ultimately, the root is external pathogens; it is not truly caused by food or phlegm alone. Zhu Danxi listed phlegm and food together, and Yan Yonghe attributed it entirely to phlegm, deviating from the *Nei Jing*’s true meaning due to Chen’s influence. Zhang Zihe rightly mocked demonic attributions and rejected Food Malaria, emphasizing contextual treatment. However, equating summerheat solely with fire and applying harsh methods (sweating, vomiting, purgation) to exhausted populations during turmoil seems biased. In prosperous times, I was unaware of such turmoil, but for those injured by overwork, deficiency is severe. They may exhibit exhaustion of the three yang meridians and should not all be treated as fire patterns with harsh methods. This highlights the difficulty of accurate medical discourse and the challenge of achieving balanced, appropriate treatment.