张氏隐庵曰∶痘乃先天之毒，疹属后天之邪。先天之止有水火，后天始备五行。产下发
声吮乳肇自后天，是以发声之时，口中有毒即咽下而归于阳明。故 之毒瓦斯发于阳明，上达于肺，出于皮毛，
肺主气而外合皮毛。是以痘毒走于血分，而气以化之为顺。 毒走于气分，而血以和之为顺。若走于血分而见云头紫
赤斑者逆也， 乃气分之毒更速于痘，若停留于胃则烂牙龈，阻滞在肺则为鼻扇喘急，发表
疏里清热解毒，事在良医之临证妙用者也。夫气为阳，血为阴，痘乃精血中毒。故应四时之
生长收藏，以合地支之数。 乃气分之毒，是以一日三烹，三而三之，以应阳九之终。痘发
于阴，故宜头面稀疏，不喜独见阳位， 发于阳，故喜大烹头面，不宜惟在心胸。此人之阴
阳血气应天地自然之道也。治 主方。
葛根 荆芥 防风 杏仁 牛蒡子 甘草 桔梗 陈橘皮
上方用泉水煎服。再随四时之气而加减用之。如寒闭者宜麻黄，热闭者宜石膏，食闭
者宜枳朴山楂，热甚者加黄芩黄连，毒甚者加
白花地丁西河柳，渴者加知母，喘者倍杏仁。盖痘疹有血气之分，而用药亦宜分别。肺主气
而心主血，故清痘之热毒宜以连为君，而芩为佐；清 之热毒，以芩为君而连佐之。又如金
银花花开黄白，藤名忍冬，能启阴气而解痘 之热毒，盖黄走血，而白走气也。若夫白花地
丁又专于 证者也。此用药之大关目，学人引伸触类微妙无穷。
张隐庵说：痘毒是先天带来的毒素，疹毒属于后天感受的邪气。先天只有水和火两种元素，后天才具备金、木、水、火、土五行。婴儿出生时发出声音并开始吮吸乳汁，这标志着后天的功能开始运作，因此在发声的时候，口中的毒气就会咽下并归属于阳明经（胃与大肠）。所以，疹毒的气机发源于阳明，向上到达肺脏，向外透出于皮毛。肺主司气，且外合于皮毛。因此，痘毒走窜于血分，由气来化解它才是顺证；疹毒走窜于气分，由血来调和它才是顺证。如果疹毒走窜于血分而呈现出如云头状的紫红色斑疹，则是逆证。疹毒作为气分之毒，其发作速度比痘毒更快，如果停留在胃部则会导致牙龈溃烂，阻滞在肺部则会出现鼻翼扇动和呼吸急促的症状。此时需要采用发表疏里、清热解毒的方法，具体运用在于良医的临床灵活变通。
气属阳，血属阴，痘毒是精血中的毒素，因此应当顺应四季的生长收藏规律，以符合地支的数理。疹毒是气分之毒，因此一日之内变化三次（指病情演变快），三乘以三得九，以应“阳九”之终数。痘毒发于阴分，所以适宜头面部稀疏，不喜欢单独出现在阳位（头面为诸阳之会）；疹毒发于阳分，所以适宜大面积爆发于头面部，不适宜只局限在心胸部位。这是人体的阴阳气血顺应天地自然之道。治疗疹毒的主方如下：
上方用泉水煎服。再根据四季气候的变化进行加减使用。如果是寒邪闭郁者适宜用麻黄，热邪闭郁者适宜用石膏，食积闭郁者适宜用枳实、厚朴、山楂，热势严重者加黄芩、黄连，毒势严重者加白花地丁、西河柳，口渴者加知母，气喘者加倍使用杏仁。大概痘疹有血分和氣分的区别，用药也应当分别对待。肺主气而心主血，所以清除痘毒的热毒适宜以黄连为君药，黄芩为佐药；清除疹毒的热毒，适宜以黄芩为君药，黄连为佐药。又如金银花花开黄白两色，藤名忍冬，能开启阴气而解除痘疹的热毒，因为黄色入血分，白色入气分。至于白花地丁又专门针对疹证。这是用药的关键所在，学习者引申触类，其中的微妙之处无穷无尽。
Zhang Yinan stated: Smallpox (Dou) toxin is the poison from congenital essence, while measles (Zhen) belongs to pathogenic factors acquired postnatally. Congenital nature consists only of Water and Fire, whereas the postnatal stage encompasses the Five Elements. The onset of crying and suckling marks the beginning of postnatal functions; thus, at the moment of crying, the toxic qi in the mouth is swallowed and directed to the Yangming channel (Stomach and Large Intestine). Therefore, the qi mechanism of Zhen toxin originates from Yangming, ascends to reach the Lung, and emerges through the skin and hair. The Lung governs Qi and corresponds externally to the skin and hair. Consequently, when Dou toxin moves into the Blood aspect, it is favorable for Qi to transform it; when Zhen toxin moves into the Qi aspect, it is favorable for Blood to harmonize it. If Zhen toxin moves into the Blood aspect and presents as cloud-like purple-red macules, this is an adverse condition. As a toxin of the Qi aspect, Zhen develops faster than Dou. If it stagnates in the Stomach, it causes gum rot; if it obstructs the Lung, it results in nasal flaring and rapid breathing. Treatment involves releasing the exterior, purging the interior, and clearing heat and detoxifying, which relies on the clinical ingenuity of skilled physicians.
Qi is Yang, and Blood is Yin. Dou toxin resides in the essence and blood, so it should correspond to the growth, development, storage, and concealment of the four seasons, aligning with the numerical order of the Earthly Branches. Zhen toxin is a toxin of the Qi aspect, so it undergoes three transformations daily (indicating rapid progression); three times three equals nine, corresponding to the culmination of "Yang Nine." Dou erupts from the Yin aspect, so it is preferable for lesions to be sparse on the head and face, avoiding exclusive occurrence in Yang regions (the head and face are the meeting place of all Yang meridians). Zhen erupts from the Yang aspect, so it prefers widespread eruption on the head and face, rather than being confined solely to the chest and heart region. This reflects the principle that human Yin-Yang and Qi-Blood follow the natural laws of Heaven and Earth. The main prescription for treating Zhen is as follows:
Puerariae Radix (Ge Gen), Schizonepetae Herba (Jing Jie), Saposhnikoviae Radix (Fang Feng), Armeniacae Semen Amarum (Xing Ren), Arctii Fructus (Niu Bang Zi), Glycyrrhizae Radix et Rhizoma (Gan Cao), Platycodonis Radix (Jie Geng), Citri Reticulatae Pericarpium (Chen Ju Pi).
Decoct the above herbs in spring water for administration. Adjust the formula according to the seasonal Qi. For closure due to cold, Ephedrae Herba (Ma Huang) is suitable; for closure due to heat, Gypsum Fibrosum (Shi Gao) is suitable; for closure due to food retention, Aurantii Fructus Immaturus (Zhi Shi), Magnoliae Officinalis Cortex (Hou Po), and Crataegi Fructus (Shan Zha) are suitable. For severe heat, add Scutellariae Radix (Huang Qin) and Coptidis Rhizoma (Huang Lian); for severe toxicity, add Violae Herba (Bai Hua Di Ding) and Salicis Tashiroanae Ramulus (Xi He Liu); for thirst, add Anemarrhenae Rhizoma (Zhi Mu); for wheezing, double the dosage of Armeniacae Semen Amarum (Xing Ren). Generally, Dou and Zhen have distinctions between Blood and Qi aspects, and medication should be differentiated accordingly. The Lung governs Qi, and the Heart governs Blood. Therefore, to clear the heat-toxin of Dou, Coptidis Rhizoma (Huang Lian) should be used as the sovereign herb, with Scutellariae Radix (Huang Qin) as the minister herb. To clear the heat-toxin of Zhen, Scutellariae Radix (Huang Qin) should be the sovereign herb, with Coptidis Rhizoma (Huang Lian) as the minister herb. Furthermore, Lonicerae Japonicae Flos (Jin Yin Hua) blooms yellow and white, and its vine is named Ren Dong (Lonicera japonica stem). It can open Yin Qi and resolve the heat-toxin of Dou and Zhen. Yellow enters the Blood, while white enters the Qi. Violae Herba (Bai Hua Di Ding) is specifically indicated for Zhen conditions. These are the key principles of medication; students who extend their understanding will find the subtleties infinite.