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，是有形可见的病证，似乎不需要通过诊脉来判断。另外，痘疹的发生与当年的岁气（气候）主导有关，似乎也不必诊脉。然而《内经》说：“医道的精微奥妙在于脉诊，不可不仔细考察；考察脉象要有纲纪，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，说明预后良好可生；如果脉象躁动不安、身体发热，说明预后不良会死。”由此可见，治疗痘疹也是需要用诊脉的。
大体上，小儿的脉象多带有紧而数的特点；疮毒之病的脉象，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，脉大表示气机亢盛，风邪与虚气相互搏结，必然形成瘾疹（皮肤红斑瘙痒等症）。”又说：“脉数而不按时节规律变化，就会发生恶疮。”
七岁以上的儿童，一息脉跳五至为平脉；七岁以下的儿童，一息脉跳六至为平脉。超过这个次数则为“太数”，属于邪气实盛；少于这个次数则为“迟”，属于正气虚弱。脉浮而数，表示表热；脉浮而迟，表示阳气衰微；脉沉而紧，表示里热；脉沉而细，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，预后凶险。凡是诊察到脉象浮取而无根底，轻飘如羹汤表面的浮油；或者脉数而急疾，接连而来如麻雀啄食般急促；或者脉细而欲散，连绵不断如蜘蛛丝般细微；或者脉迟而欲绝，滴滴答答如屋顶漏水般断续；或者脉沉而偶尔出现，如鱼跃出水面般乍现乍隐，这些都是死脉。
凡是痘疹病情严重的，可以通过脉候来推断吉凶：脉象洪大充实的为吉兆，脉象浮数、虚弱细小的为凶兆。
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，两手脉象皆豁大而略微偏数。丹溪判断这是由于劳倦内伤所致。当时乡里中多发痘疹，虽然患者已不知人事，但喂药能喝下，喂粥能吞咽。于是丹溪教他用人参、白术（原文“者”疑为“术”之误）、当归、苍术、陈皮组成的大剂量浓煎药液让他服用。服了二十多帖后，痘疹才开始发出；又服了二十帖，脓液形成，全身皮肤溃烂。有人问：“这种劳损之病很可怕，为什么不用陈氏的全方来治疗？”丹溪回答说：“这仅仅是虚证，没有寒邪，只需坚守前方，再服几十帖就能痊愈。”后来询问病因，是因为前四五天，担心会有出痘的风险，于是极力从事砍柴采集等体力劳动，连日出汗过多。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施治的一个典型案例。
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 prevailing annual climate (Sui Qi), suggesting that pulse diagnosis might also be deemed superfluous. However, the *Classic of Internal Medicine* states: "The subtlety lies in the pulse; it must not be neglected. To examine it requires a systematic approach, beginning with the differentiation of Yin and Yang." Thus, pulse diagnosis is indispensable. Ancient sages have said: "If the pulse is calm and the body cool in cases of smallpox/chickenpox, life is preserved; if the pulse is restless and the body hot, death ensues." This demonstrates that pulse diagnosis is indeed applied in the treatment of rashes and eruptions.
Generally speaking, children's pulses often present as tight and rapid. The pulse associated with toxic sores or eruptions frequently appears floating, large, and rapid. The *Treatise on Cold Damage Disorders* (*Shanghan Lun*) states: "Floating indicates wind invasion or deficiency; large indicates excessive Qi. When wind and deficiency Qi contend, urticaria (skin rashes) will inevitably form." It further states: "A rapid pulse that does not follow regular intervals gives rise to malignant sores."
For children over seven years old, five beats per respiration cycle constitute a normal pulse; for those under seven, six beats per cycle are considered normal. Exceeding this frequency indicates "excessive rapidity," signifying an excess of pathogenic factors. Falling short indicates "slowness," signifying a deficiency of healthy Qi. A floating and rapid pulse indicates exterior heat; a floating and slow pulse indicates the decline of Yang Qi. A deep and tight pulse indicates interior heat; a deep and thin pulse indicates the depletion of primordial Qi.
Smallpox and chickenpox are Yang diseases. Their pulses should ideally exhibit a洪 (surging/full) and solid 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 ominous. Any pulse found to be floating without a root, light and fleeting like fat floating on soup; or rapid and frantic, coming continuously like a sparrow pecking; or thin and dissipating, lingering like a spider's thread; or slow and nearly absent, dripping like water from a leaking roof; or deep and intermittent, appearing suddenly like a fish leaping—all are considered death omens.
In severe cases of smallpox, prognosis can be determined by pulse examination: a洪 (surging) and solid pulse is auspicious, whereas a floating, rapid, deficient, and small pulse is inauspicious.
Zhu Danxi once treated a sixteen-year-old male patient who presented with fever, confusion, blindness, and deafness. His pulses in both hands were broad (Huo) and 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 when offered and sip porridge when fed. Zhu advised administering a large dose of strong decoction containing Ren Shen (Ginseng Root), Bai Zhu (Atractylodes Rhizome), Dang Gui (Angelica Sinensis Root), Cang Zhu (Atractylodes Lancea Rhizome), and Chen Pi (Citrus Reticulata Pericarp). After more than twenty doses, the rash began to erupt. After another twenty doses, pus formed, and the skin became extensively ulcerated. Someone asked, "This consumption-like condition is terrifying; why not use Chen's complete formula?" Zhu replied, "This is merely deficiency without cold. Simply adhere to the previous prescription, and after dozens more doses, he will recover." Later inquiry revealed the cause: fearing the onset of smallpox four or five days prior, the patient had engaged in strenuous firewood gathering, resulting in profuse sweating over several days. This case illustrates diagnosing deficiency through the broad pulse and treating eruptions based on pulse findings.