凡出疹，自热起至收完，但看右手一指，脉洪大有力，虽有别证，亦不为害，此定存亡之要法
也。
景岳曰∶按此即阳证得阳脉之义，若细软无力，则阳证得阴脉矣，一元气既弱，安能胜此邪毒
？是即安危之基也。故凡诊得阴脉者，印当识为阴证而速救元神，宜用伤寒温补托法，参酌治之。
若执以麻疹为阳毒而概用清寒，则必不免矣。
疹虽非痘之比，然亦由胎毒蕴于脾肺，故发于皮毛肌肉之间，但一时传染，大小相似，则未有
不由天行疠气而发者。此其源虽内发，而证多属表，故其内为胎毒，则与痘证同，外有表邪，则与
伤寒类。其为毒也，总由君相二火，燔灼太阴，而脾肺受之。故其为证，则有咳嗽喷嚏，面肿腮赤
，目胞浮肿，眼泪汪汪，鼻流清涕，呵欠闷顿，乍凉乍热，手足稍冷，夜卧惊悸，或恶心呕哕，或
以手掐面日唇鼻者，是即出疹之候，便宜用解毒散邪等药，不使留停于中，庶无他患。且凡是疹证
，必其面亦、中指冷而多嗽，又必大热五六日，而后见红点遍身，此其所以与痘与伤寒有异也。
一、痘欲尽发而不留，疹欲尽出则无病。邪气郁遏则留而不去，正气损伤则困而不伸。毒归五脏
，变有四证，归脾则泄泻不止，归心则烦热不退而发惊，归肺则咳嗽血出，归肾则牙龈烂而疳蚀。
程氏曰∶麻疹初出，类伤风寒，头疼咳嗽，热甚，目赤颊红。一二日内即出者轻，必须解表，
忌见风寒、荤腥浓味，如犯之，恐生痰涎，变为惊搐，必致危矣。如初起吐泻交作者顺，干呕霍乱
者逆，欲出不出者危亡立至。
徐氏曰∶痘自里而出于脏故重，疹自表而出于腑故轻。
景岳曰∶痘疹之属有四肿，曰痘，曰疹，曰麻，曰斑也。痘则陆续渐出，自小而大，或稀或密
，部位颗粒有辨也。疹则一齐发出，大者如苏子，次者如芥子，小者如蚕子，而成粒成片者是也。
麻则最细而碎，如蚊迹模糊者是也。斑则无粒，惟成片，红紫如云如锦者是也。大都疹与麻斑同类
，即发斑伤寒之属，而痘则本非其类也。盖痘毒本于肝肾，出自中下二焦，是以终始不妨于食，而
全赖水谷为主，所以能会则吉，不能食则凶。故治痘者，不可罔顾脾胃。麻疹之毒，则由表邪不解
而内犯太阴阳明，病在上中二焦，所以多不能食，故治麻疹者，但宜解散火邪，邪散则自能食矣。
是痘疹之治，当各有所重者如此。
凡是出疹，从发热开始到皮疹完全消退，只要观察右手寸口脉的浮取（一指），若脉象洪大有力，即使伴有其他症状，也不会造成危害，这是判断生死存亡的关键方法。
张景岳说：按照这个观点，就是阳证出现阳脉的意义。如果脉象细软无力，那就是阳证出现了阴脉。既然元气已经虚弱，怎么能抵御这种邪毒呢？这就是安危的根本所在。所以凡是诊察到阴脉的，应当识别为阴证并迅速挽救元神，适宜采用《伤寒论》中的温补托毒治法，斟酌情况治疗。如果固执地认为麻疹是阳毒而一概使用寒凉药物，那就必然会导致不良后果。
疹虽然不能与痘疮相比，但也由胎毒蕴结在脾肺所致，因此发于皮毛肌肉之间。只是一时之间传染，大小相似，没有不是由于天行疠气（流行性疫气）引发的。这个病源虽然内发，但证候多属于表证，所以其内在有胎毒，这与痘疮相同；外在有表邪，这就与伤寒类似。其中的毒邪，总归是由君火和相火燔灼太阴经，导致脾肺受病。所以其证候表现，有咳嗽喷嚏、面部肿胀腮部发红、眼睑浮肿、眼泪汪汪、流清鼻涕、呵欠困顿、忽冷忽热、手足稍冷、夜间睡眠惊悸，或者恶心呕吐，或者用手抓挠面部嘴唇鼻子等，这些都是出疹的先兆，此时应该立即使用解毒散邪的药物，不让邪气留滞体内，这样才不会有其他祸患。而且凡是疹证，必定见面色异常、中指发冷且多咳嗽，又必须经过五六天的大热之后，全身才出现红点，这就是它与痘疮和伤寒不同的地方。
第一，痘疮想要完全发出而不留滞，疹子想要完全透出就没有疾病。邪气郁结遏制就会留滞不去，正气受损就会困顿无法伸展。毒邪归于五脏，变化有四种证候：归于脾则泄泻不止，归于心则烦热不退并发惊风，归于肺则咳嗽出血，归于肾则牙龈腐烂并发生疳蚀。
程氏说：麻疹初起，类似伤风寒，头痛咳嗽，热势严重，眼睛红脸颊红。一两天内就发出的病情较轻，必须解表，忌讳接触风寒、荤腥浓味，如果触犯，恐怕产生痰涎，变为惊厥抽搐，必然导致危险。如果初起时吐泻同时发作属于顺证，干呕霍乱属于逆证，想发出不来则危亡立刻到来。
徐氏说：痘疮从里出于脏所以病情重，疹从表出于腑所以病情轻。
张景岳说：痘疹这类疾病有四种肿出物，叫作痘、疹、麻、斑。痘则是陆续逐渐发出，由小变大，或稀或密，部位颗粒可以分辨。疹则是一齐发出，大的像苏子（紫苏籽），小的像芥子，更小的像蚕子，形成颗粒成片的就是疹。麻则是最细碎，像蚊子叮咬的痕迹模糊不清的就是麻。斑则没有颗粒，只是成片，红紫色像云锦一样的是斑。大多疹与麻斑同类，即属于发斑伤寒一类，而痘则本来不属于这一类。大概痘毒本源于肝肾，出自中下二焦，所以从头到尾不妨碍进食，完全依赖水谷精气为主，所以能进食则吉，不能进食则凶。所以治疗痘疮的人，不可不顾及脾胃。麻疹的毒邪，则由表邪不解而内犯太阴、阳明经，病在上中二焦，所以大多不能进食，因此治疗麻疹的人，只宜解散火邪，邪气散去则自然能进食了。这就是痘疹的治疗，应当各自有所侧重的原因如此。
In all cases of exanthema (rash), from the onset of fever until the eruption subsides completely, if one observes the superficial pulse at the right cun position (one finger depth) and finds it surging (Hong) and forceful, even if other symptoms are present, they will not cause harm. This is the critical method for determining survival or death.
Zhang Jingyue stated: According to this principle, it means a Yang syndrome presenting with a Yang pulse. If the pulse is fine and soft without force, it indicates a Yang syndrome presenting with a Yin pulse. Once the primordial Qi is weakened, how can it overcome such pathogenic toxins? This constitutes the foundation of safety or danger. Therefore, whenever a Yin pulse is diagnosed, it should be recognized as a Yin syndrome, and immediate rescue of the Yuan Shen (Primordial Spirit) is required. It is appropriate to employ the warming and tonifying methods to support the exterior as described in Shanghan Lun (Treatise on Cold Damage), adjusting the treatment according to circumstances. If one stubbornly considers measles as a Yang toxin and indiscriminately uses cold-natured clearing herbs, adverse consequences are inevitable.
Although exanthema differs from variola (smallpox), it also arises from fetal toxins accumulating in the Spleen and Lung. Thus, it manifests between the skin/hair follicles and muscles. Due to transient contagion, the lesions appear similar in size across individuals, and none arise without the influence of epidemic pestilential qi (Tianxing Liqi). Although the source originates internally, the clinical presentation mostly belongs to the Exterior level. Internally, the presence of fetal toxins aligns with variola; externally, the presence of exterior pathogens resembles Shaoyang/Taiyang cold damage. The toxicity generally stems from the blazing of Ministerial Fire and Sovereign Fire affecting the Taiyin channel, thereby injuring the Spleen and Lung. Consequently, symptoms include coughing and sneezing, facial swelling with red cheeks, edematous eyelids, watery eyes, clear nasal discharge, yawning and lethargy, alternating chills and fever, slightly cold hands and feet, nocturnal sleep disturbances with palpitations, nausea or vomiting, or scratching the face, lips, and nose. These are signs preceding the eruption of exanthema. At this stage, one should promptly administer herbs that resolve toxins and disperse pathogens to prevent stagnation within, thereby avoiding further complications. Furthermore, in all cases of exanthema, there is invariably abnormal facial complexion, coldness of the middle finger, and frequent coughing. High fever persists for five to six days before red spots appear all over the body. This distinguishes it from variola and cold damage.
1. For variola, the goal is complete eruption without retention; for exanthema, complete emergence ensures no disease remains. If pathogenic factors are constrained and stagnant, they remain unresolved; if healthy Qi is damaged, it becomes exhausted and fails to expand. If toxins settle in the Five Zang organs, four types of transformations occur: settling in the Spleen leads to incessant diarrhea; settling in the Heart leads to persistent irritability and heat with convulsions; settling in the Lung leads to coughing with hemoptysis; settling in the Kidney leads to rotting gums and gan erosion (nutritional deficiency ulcers).
Master Cheng stated: Measles at the initial stage resembles wind-cold injury, with headache, cough, severe fever, red eyes, and flushed cheeks. If eruptions appear within one or two days, the condition is mild; exterior resolution is necessary. One must avoid exposure to wind-cold and rich, greasy foods. Violating these precautions may generate phlegm-saliva and transform into convulsions, leading to critical danger. If vomiting and diarrhea occur simultaneously at the onset, it is a favorable sign (Shun); dry vomiting and cholera-like symptoms are unfavorable (Ni); failure to erupt indicates imminent peril.
Master Xu stated: Variola emerges from the interior to the Zang organs, hence it is severe; exanthema emerges from the exterior to the Fu organs, hence it is mild.
Zhang Jingyue stated: There are four types of eruptive swellings in this category: variola (Dou), exanthema (Zhen), morbilli (Ma), and macules (Ban). Variola erupts gradually and successively, growing from small to large, varying in density, with distinct individual papules. Exanthema erupts simultaneously; the largest are like perilla seeds, medium-sized like mustard seeds, and smallest like silkworm eggs, forming granular patches. Morbilli are the finest and fragmented, resembling blurred mosquito bite marks. Macules lack granularity, appearing only as patches, red-purple like clouds or brocade. Generally, exanthema and morbilli/macules are of the same category, belonging to the spectrum of cold damage with macular eruption, whereas variola does not belong to this category. The toxin of variola originates from the Liver and Kidney, emerging from the Middle and Lower Jiao. Therefore, appetite remains unaffected throughout, relying entirely on grain and water essence for recovery; thus, ability to eat signifies auspiciousness, while inability to eat signifies ominous prognosis. Hence, treating variola requires prioritizing the Spleen and Stomach. The toxin of exanthema/morbilli arises from unresolved exterior pathogens invading the Taiyin and Yangming channels, affecting the Upper and Middle Jiao. Consequently, loss of appetite is common. Therefore, treating exanthema/morbilli requires only dispersing fire pathogens; once the pathogen is dispersed, appetite returns naturally. This explains why the treatment of variola and exanthema must have different emphases.