白 一症，考古方书无专条论及，间有在 疹门中发明一二，究未能尽其底蕴。今温热证中，每多发出如粞如粟，
色白形尖者，谓之白 。有初病即见者，有见而即愈者，有见而危殆者，有病经日久， 疹已见，补泻已施之后，仍然
发此而愈者。泛称时气所致，殊不知致病之由既异，治疗之法不同，不可不与 疹详辨而审处之也。盖伤寒传经，热病
汗出不彻，邪热转属阳明，多气多血之经，或由经入府，受热蒸灼，营伤血热不散，而里实表虚，热气乘虚出于肤腠，
故稀如蚊迹，稠如锦纹者为斑；紫黑为胃烂而不治也。时行风热之气，侵入肺虚血热之体，失于清透，伤及手太阴血分，
乘虚出于皮肤，如沙如粟而色红琐碎者为麻。或岁当火运，复感时厉之毒，即咽痛而成丹痧及烂喉痧之类，为最剧者也。
至于白 一症，则温热暑邪病中，必兼湿为多。盖伏气之发，本从内出，然必因外感，及人身素蕴之湿，与外触之邪，
互相蒸发，上甚为热。初病治法，设不用清透渗解，则肺为热伤，气从中馁，不能振邪外解，热渐陷于营分，转投清营
滋化，热势稍缓，而肺气亦得借以自复，所留之湿，仍从上焦气分寻隙而出，于是发为白 。以肺主气，故多发于颐、
项、肩、背、胸臆之间；白为肺之色，光润为湿之余气，至此而邪始尽泄也。甚有几经补泻之后，病仍不解，忽然发此
而愈者，以其人之气液内复，邪自外透，故不治亦愈也。若其根本已虚，无气蒸达，多有延为衰脱者。故此症以元气未
漓，色润晶莹，有神者为吉；枯白乏泽，空壳稀散者，为气竭而HT 。总以形色之枯润，卜其气液之竭与否也。大抵此
症，
在春末、夏初，暑湿之令为甚，秋冬则间有之，要不出乎手经受病，仍从手经发泄，不比足经之邪，可从下解也。夫肺
为主气之藏，气旺则邪从外解，上泄而病愈，气衰则邪正并竭，虽发必朽白无神而难治。观《内经》暑与湿同推，仲圣
痉湿 合论，益知暑热温邪症中，多夹湿邪，更无疑矣。一隙微明，以俟高贤正之。
白疹（一种表现为白色、形如粟米的皮疹症状），查阅古代方书，没有专门的条文论述它，偶尔在麻疹门类中提及一二，但终究未能探究其根本原理。如今在温热病证中，经常见到发出如米屑如粟粒般、颜色白而形状尖小的皮疹，称之为白疹。有的初起病即出现，有的出现后随即痊愈，有的出现后病情危重，有的患病日久，在疹子已出、补泻治法都已施用的情况下，仍然发出此症而痊愈。一般泛称为时气所致，却不知道致病原因既然不同，治疗方法也各异，不可不与麻疹详细辨别并审慎处理。
大概伤寒病传经，热病发汗不彻底，邪热转属阳明经（多气多血之经），或由经传入腑，受热蒸灼，营阴受损、血热不散，导致里实表虚，热气乘虚出于皮肤腠理，所以稀疏如蚊迹、稠密如锦纹的是斑疹；颜色紫黑则是胃烂，属于不治之症。时行风热之气，侵入肺虚且血热的体质，失于清透，伤及手太阴肺经的血分，乘虚出于皮肤，如沙如粟且颜色红而琐碎的是麻疹。或者正值火运之年，又感受时厉的毒气，立即咽喉疼痛而成丹痧及烂喉痧之类，这是最严重的病症。
至于白疹这一症状，则在温热暑邪病中，必定兼夹湿邪居多。因为伏气温病的发作，本从体内发出，但必须因外感引发，加上人体素来蕴藏的湿邪，与外触之邪互相蒸发，向上熏蒸化为热。初病时的治法，如果不用清透渗利的方法解除，则肺被热邪所伤，气从中馁弱，不能振奋邪气向外解表，热邪逐渐陷入营分，转而投用清营滋化之法，热势稍缓，肺气也能借此自我恢复，所残留的湿邪，仍从上焦气分寻找缝隙而出，于是发为白疹。因为肺主气，所以多发于面颊、颈部、肩部、背部、胸部之间；白色为肺之色，光润是湿之余气，至此邪气才完全泄出。甚至有经过几次补泻治疗后，病仍未解，忽然发出此症而痊愈的，是因为人的气液内部恢复，邪气自然从外表透发，所以即使不治疗也能痊愈。如果其根本已经虚弱，没有阳气蒸达，多有拖延成为衰脱证的。因此此症以元气未耗散、色泽润泽晶莹、有神者为吉兆；枯白无光泽、空壳稀散的，为气竭而预后不良。总之是以形色之枯润，来推测气液是否枯竭。大抵此症，在春末、夏初，暑湿时令最为盛行，秋冬则间或有之，总不出乎手经受病，仍从手经发泄，不像足经之邪，可从下焦解决。肺为主气之脏，气旺则邪从外表解，上泄而病愈，气衰则邪正俱竭，虽然发出皮疹也必枯白无神而难治。观《内经》将暑与湿并列推论，仲景将痉病、湿病合论，更加知道在暑热温邪病症中，多夹有湿邪，更无疑义了。一点微小的见解，以此等待高明贤者指正。
Bai Zhen (White Rash), a specific symptom, is not discussed in dedicated sections in ancient medical texts. Occasionally mentioned in the context of measles (Ma Zhen), these references fail to fully explore its underlying principles. In contemporary warm-heat diseases, it is common to observe rashes resembling rice grains or millet seeds, white in color and pointed in shape, referred to as Bai Zhen. Some cases present at the onset of illness, some resolve immediately upon appearance, some become critical, and some persist for a long duration, appearing even after other rashes have emerged and tonifying or purging treatments have been applied, ultimately leading to recovery. It is generally attributed to seasonal qi (Shi Qi), but this overlooks that differing etiologies require distinct therapeutic approaches. Therefore, it must be carefully differentiated from measles (Ma Zhen) and managed prudently.
Generally, when Shaoyang disease transmits through meridians, or when heat diseases are treated with sweating that is incomplete, pathogenic heat may transfer to the Yangming Meridian (a meridian abundant in qi and blood). If the pathogen moves from the meridian to the fu organs, intense heat steams and scorches, damaging Ying (Nutritive) Yin and causing Blood Heat to stagnate. This results in interior excess and exterior deficiency, allowing hot qi to escape through the skin and pores due to weakness. When sparse like mosquito bites or dense like brocade patterns, it is classified as Ban (Macules/Purpura); purple-black discoloration indicates stomach rot and is incurable. Seasonal wind-heat pathogens invading constitutions with Lung deficiency and Blood Heat, if not cleared and vented properly, damage the Blood aspect of the Hand-Taiyin Lung Meridian. Emerging through the skin like sand or millet with red, fragmented colors, it is identified as Ma (Measles). Alternatively, during years governed by Fire運 (Fire Operation), exposure to severe seasonal toxins can cause sore throat leading to Dan Sha (Scarlet Fever-like rash) or Lan Hou Sha (Rotten Throat Scarlatina), which are the most severe conditions.
Regarding Bai Zhen, it predominantly occurs in warm-heat and summer-heat diseases complicated by Dampness (Shi). The eruption of latent pathogens originates internally but requires external triggers. It involves the interaction between the body's inherent dampness and externally contacted pathogens, evaporating together to generate upper heat. In early treatment, if clearing, venting, and draining methods are not employed, the Lungs are damaged by heat, Qi becomes deficient internally, and fails to expel pathogens outward. Heat gradually sinks into the Ying level. Switching to Ying-clearing and nourishing therapies may slightly alleviate heat and allow Lung Qi to recover. The remaining dampness then exits via the Upper Jiao Qi level, manifesting as Bai Zhen. Since the Lung governs Qi, rashes often appear on the cheeks, neck, shoulders, back, and chest. White corresponds to the Lung's color; luster indicates residual dampness, signifying complete pathogen expulsion. Recovery may occur suddenly after multiple tonifying/purging treatments if internal Qi and fluids have restored, allowing pathogens to vent outward spontaneously. However, if the root is deficient without Qi vaporization, it may progress to collapse. Thus, auspicious signs include intact Yuan Qi, lustrous and bright texture, and spirit; inauspicious signs include withered white color, lack of luster, hollow appearance, and sparsity, indicating Qi exhaustion. Prognosis depends on whether Qi and fluids are depleted, assessed by the dryness or moisture of the rash's appearance. Generally, this condition is prevalent in late spring and early summer during damp-heat seasons, occasionally occurring in autumn and winter. It involves the Hand meridians and vents through them, unlike Foot meridian pathogens which can be resolved downward. The Lung is the zang organ governing Qi; robust Qi allows pathogen expulsion upward, leading to recovery, while weak Qi leads to simultaneous depletion of pathogen and healthy Qi, resulting in withered, spiritless rashes that are difficult to treat. The *Neijing* associates Summerheat with Dampness, and Zhang Zhongjing combines Spasm and Dampness discussions, confirming that warm-heat pathogens often accompany Dampness. This minor insight awaits correction by experts.