疮疹之疾，有形之证，无所用诊。又，岁气主之，似不必诊。经曰∶微妙在脉，
不可不察，察之有纪，从阴阳始。是则不可不诊也。先哲有言曰∶痘疹脉静身凉者
生，脉躁身热者死，可见疮疹亦用诊矣。大抵小儿之脉，多带紧数，疮毒之脉，又
多浮大而数，伤寒论云∶浮为风虚，大为气强，风气相搏，必成瘾疹。又曰∶数脉
不时，则生恶疮也。七岁以上，五至为平，七岁以下，六至为平，过则为太数，邪
气实也，不及为迟，正气虚也，浮而数，表热也，浮而迟，阳气衰也，沉而紧，里
热也，沉而细，元气脱也。疮疹为阳病，其脉浮沉俱宜带洪实，若弱而无力，为阳
病见阴脉凶。凡诊得浮而无根，瞥瞥如羹上肥，数而急疾，连来如雀之啄，细而欲
散、萦萦如蛛之丝，迟而欲绝，滴滴如屋之漏，沉而时见，如鱼之跃，皆死脉也。
凡痘子势重者，以脉候之，脉洪实者吉，浮数虚小者凶。丹溪治一男子年十六岁，
发热而昏，目无见，耳无闻，两手脉皆豁大而略数。知其为劳伤矣，时里中多发痘
者，虽不知人，与药则饮，与粥则啜，遂教以参、者、当归、苍术、陈皮大料浓
与之饮，至二十余帖，痘始出，又二十帖，则成脓 ，身无全肤。或曰，病劳可畏，
何不用陈氏全方治之。予曰此但虚尔，无寒也，只守前方，又数十帖而安。后询其
病因，为先四五日，恐有出痘之患，遂极力采樵，连日出汗甚多。此以脉之豁大而知
其虚，乃痘疹因脉施治之一例也。
痘疹这类疾病，是有形可见的病症，似乎不需要通过诊脉来判断。此外，痘疹的发生与当年的岁气（气候运气）主导有关，看起来似乎也不必诊脉。然而，《内经》说：“医道的微妙之处体现在脉象上，不可不仔细考察；考察脉象有纲纪，要从辨别阴阳开始。”既然如此，那么诊脉就是不可省略的。先前的哲人曾说：“痘疹患者如果脉象平静、身体凉爽，说明预后良好可以存活；如果脉象躁动不安、身体发热，则预后不良会导致死亡。”由此可见，治疗痘疹也是需要使用诊脉方法的。
大体上，小儿的脉象多带有紧而数的特点；疮毒（痘疹类病邪）引起的脉象，又多表现为浮大且数。《伤寒论》中说：“脉浮表示风邪侵袭或正气虚弱，脉大表示气机强盛，风邪与虚气相互搏结，必然形成瘾疹（荨麻疹类皮肤病）。”又说：“脉数而不按时令规律出现，就会发生恶疮。”
七岁以上的儿童，脉搏一息跳动五次为正常平脉；七岁以下的儿童，脉搏一息跳动六次为正常平脉。超过这个次数则为“太数”，属于邪气实盛的证候；少于这个次数则为“迟”，属于正气虚弱的证候。脉浮且数，表示表热；脉浮且迟，表示阳气衰微；脉沉且紧，表示里热；脉沉且细，表示元气脱失。
痘疹属于阳病，其脉象在浮取和沉取时都应当带有洪大充实的特点。如果脉象微弱无力，这是阳病出现了阴脉，属于凶险之兆。凡是诊察到脉象浮取而无根底，轻飘如羹汤表面的浮油；或者脉数而且急疾，接连不断如同麻雀啄食；或者脉细弱将要散失，连绵不绝如同蜘蛛丝；或者脉迟几乎要断绝，滴滴答答如同漏屋滴水；或者脉沉偶尔出现，如同鱼儿跳跃，这些都是死脉。
凡是痘疹病情严重的患者，通过脉象来候察，脉象洪大充实的是吉兆，脉象浮数、虚弱细小的则是凶兆。朱丹溪曾治疗一名十六岁的男子，患者发热且神志昏蒙，眼睛看不见，耳朵听不见，两手脉象都豁大而略微偏数。丹溪判断这是由于劳倦损伤所致。当时乡里中多发痘疹，虽然患者已不知人事，但给药能喝，给粥能吃。于是丹溪教导使用人参、白术（原文“者”通“术”，指白术）、当归、苍术、陈皮，加大剂量浓煎让患者服用。服了二十多剂后，痘疹才开始发出；又服了二十剂，脓液形成，全身皮肤溃烂。有人问：“这种虚损病很可怕，为什么不用陈氏的全方来治疗呢？”丹溪回答说：“这只是单纯的虚证，没有寒邪，只需坚守前面的方子，再服几十剂就能痊愈。”后来询问病因，是因为前四五日，担心会有出痘疹的祸患，于是极力从事砍柴采集等体力劳动，连续几天出汗非常多。这是通过脉象的豁大来判断其虚损，乃是根据痘疹患者的脉象来实施治疗的典型案例。
Diseases such as smallpox and chickenpox manifest with visible physical signs, seemingly rendering pulse diagnosis unnecessary. Furthermore, the occurrence of these diseases is governed by the annual climate qi (seasonal climatic influence), suggesting that pulse diagnosis might also be deemed superfluous. However, the *Classic of Internal Medicine* (*Huangdi Neijing*) states: "The subtlety of medicine lies in the pulse; it must not be neglected. The principle of examination has its discipline, beginning with the differentiation of Yin and Yang." Thus, pulse diagnosis is indispensable. Ancient sages have said: "In smallpox and chickenpox, if the pulse is calm and the body cool, life is preserved; if the pulse is restless and the body hot, death ensues." This demonstrates that pulse diagnosis is indeed employed in treating these eruptions.
Generally speaking, children's pulses often present as tight and rapid. Pulses associated with toxin eruptions are frequently floating, large, and rapid. The *Treatise on Cold Damage* (*Shanghan Lun*) states: "Floating indicates wind pathogen or deficiency; large indicates strong Qi. When wind and deficiency contend, urticaria-like rashes will inevitably form." It further states: "If the rapid pulse appears irregularly, malignant sores will arise."
For children above seven years old, five beats per respiration constitute a normal pulse. For children below seven years old, six beats per respiration constitute a normal pulse. Exceeding this frequency indicates "excessive rapidity," signifying excess of pathogenic factors. Falling short indicates "slowness," signifying deficiency of healthy Qi. A floating and rapid pulse indicates exterior heat; a floating and slow pulse indicates decline of Yang Qi. A deep and tight pulse indicates interior heat; a deep and thin pulse indicates depletion of Yuan Qi (Original Qi).
Smallpox and chickenpox are Yang diseases. Their pulses should ideally exhibit a洪 (Hong/Full) and substantial quality upon both superficial (floating) and deep (sinking) palpation. If the pulse is weak and forceless, it represents a Yin pulse appearing in a Yang disease, which is an ominous sign. Any pulse that is floating without root, light and fleeting like fat floating on soup; or rapid and urgent, continuous like a sparrow pecking; or thin and dissipating, lingering like a spider's silk; or slow and nearly absent, dripping like water from a leaking roof; or deep and intermittent, like a fish jumping—all are considered death pulses.
In severe cases of smallpox, prognosis based on pulse is favorable if the pulse is Hong and substantial, but unfavorable if it is floating, rapid, deficient, and small. Zhu Danxi once treated a sixteen-year-old male who presented with fever, coma, blindness, and deafness. His pulses were both broad (Huo) and large, slightly rapid. He diagnosed this as damage due to overexertion. At that time, smallpox was prevalent in the village. Although the patient was unconscious, he could swallow medicine and porridge when offered. Zhu advised using a heavy decoction of Renshen (Ginseng Radix et Rhizoma), Baizhu (Atractylodis Macrocephalae Rhizoma), Danggui (Angelicae Sinensis Radix), Cangzhu (Atractylodis Rhizoma), and Chenpi (Citri Reticulatae Pericarpium). After more than twenty doses, the eruption began to appear. After another twenty doses, pus formed, and the skin became extensively ulcerated. Someone asked, "This deficiency condition is terrifying; why not use Chen's complete formula?" Zhu replied, "This is merely deficiency without cold. Stick to the previous prescription, and after dozens more doses, he will recover." Later inquiry revealed that four or five days prior, fearing the onset of smallpox, the patient had engaged in strenuous firewood gathering, sweating profusely for several consecutive days. This case illustrates diagnosing deficiency through the broad pulse and treating smallpox based on pulse findings.