诸痛为实，诸痒为虚。实者，邪气实；虚者，正气虚也。盖疮疹为火，火盛则痛，
火微则痒，故常作痛者，此邪气之实也。痘疮之毒，发于皮毛肌肉之间，气以束之，血
以润之，酝酿其毒以抵于化，在正气周全而不舍，毒瓦斯变化而未成，则郁而作痛，此其
常也。毒化脓成，其痛自己。至于肉如刀割，肤如锥刺，大痛不止，叫号多哭者，此
则皮伤肉，故不胜其毒，又痛之变，而为坏症也。常作痒者，此正气之虚也。《经》曰∶
胃者，水谷之海，六腑之大源也。五味入口，则藏于胃，以养五脏。若胃气既虚，则
水谷不化，津液内竭，不能输精于皮毛，气失其卫，血失其荣，不能酝酿毒瓦斯以至成，
乃使毒瓦斯浮沉隐伏，聚散倏忽，灼于皮毛，所以痒也，其治宜补气血，和中托里，其痒
必已。若至瘙痒不止，爬搔破坏皮脱肉坑者，此毒瓦斯内陷，正气外脱，不旋踵而告受
矣。然先痛后痒者，此常候也。盖先则毒未解化，其火正盛，宜尔作痛，厥后脓成，毒
解火气渐微，宜尔作痒也。但痛痒俱不宜甚耳。
《经》曰∶诸痛痒疮皆属心火。火炽则血热，热则干涸，干涸则气滞。而作痛也。
然初出时即痛者，是发未尽，而热毒燎灼于肌肤也。既出稠密而痛者，是毒盛而血瘀滞
也。六日以前多用发散，六日以后多用活血。因干滞而痛者，则以水杨汤浴之。至于
痘疮发痒，如能食而便坚者，邪气内实，正气外虚也。倦食而泄泻者，正气内虚，邪气
外实也。更有火邪搏于肌肤之间，不能即出，以致燥灼腠理而痒者。亦有醉酒之人近
炙，或衣被重复而发痒者。更有血方流行，而为风寒外束，故郁滞而作痒者。总痘色紫
赤，饮食能进，而气血充足者，其痒属血热，治宜清凉解毒。如色不红活，乳食不
进，而气血不足者，其痒属虚寒。然胃主肌肉，又为气血之源，故治并宜调脾进食，活
血匀气，则免痒塌之患。总而言之，痛为实，痒为虚；热微则痒，热甚则痛；痛痒皆
属于火，而虚实大有不同矣。
虚则为痒，痛则为实者，大概言之也。空则必痒，痒则必塌，理势之必然也。但焦
紫与灰白，其症将危，势必俱痒。可见气虚者作痒，而血热者亦作痒，故贵治者于起胀
之日，如血热者，先为清热凉血；气虚者，先为补中益气，则自无此患，如待症成，而
后治之，必难愈矣。然其人能食，或大便坚，抓破之处，复灌成脓，其无痘处，又出
一番，大小不一，是虽尽破，尚可救治，若瘙痒之时，其人颠倒闷乱，抓破之处，不复
灌成脓水，或成坑窟，或即干黑，或皮自脱，又兼呛水呕食，水浆不进，泄泻失音，
寒战切牙，手足厥逆，腹胀啼叫，是皆死症也。然在初见粘而遍身痒者，此邪气欲出，
因皮肤闭密，其火游移往来，故痒也。引与伤寒太阳病身痒汗不出者同治法，宜使腠理
开通，则邪气得泄，痘起而痒自去，所谓火郁则发之义也。若脓灌已成，势将收敛而痒
者，是邪气将散，正气欲复荣卫和阳，故知
痒也。此与诸疮疖类，将痊而痒者相同，不须忧虑，但谨记之，勿令搔破液溃，扬起壮
灌浆，当血化为水，水为成脓之时，其毒未化，而浑身瘙痒，爬搔不宁者，此为恶候，
是与伤寒阳明经痛皮中如虫行者同论。此所谓虚风外搏，邪气内强也。有痂落后而疤痕
痒者，因荣血耗损，皮肤干燥，是以浮火游行，火甚则痛，火微则痒耳，治宜清火滋阴
为主。大抵出形而皮肉红艳，起发而皮嫩多水者，其后必然痒塌，不可不预为调理也。
然痒塌二症相因，故塌者，未必不痒，痒者，未必水塌。不塌而痒，痒可治也；不痒
而塌，塌可治也；塌痒并作者，定然难疗。至若爬破，如汤火泡者，不治。并气离血
散，陷塌发痒而无脓者，不治。
各种疼痛属于实证，各种瘙痒属于虚证。实证，是指邪气盛实；虚证，是指正气虚弱。疮疹是由火邪引起，火势旺盛则产生疼痛，火势微弱则产生瘙痒，所以经常感到疼痛的，这是邪气盛实的表现。痘疮的毒气，发于皮毛肌肉之间，由气来约束它，由血来滋润它，酝酿其毒性以使其转化。如果正气周全而不松懈，毒气变化但未完全形成，就会郁结而产生疼痛，这是正常情况。当毒气化为脓液而成形时，疼痛自然停止。至于像肉被刀割、皮肤被锥刺一样剧烈疼痛不止，大声呼叫哭闹的，这是因为皮肉受损，无法承受毒性，这是疼痛的变证，属于坏症（不良预后）。经常感到瘙痒的，这是正气虚弱的表现。《黄帝内经》说：胃是水谷之海，是六腑的大源头。五味入口后，藏于胃中，用来滋养五脏。如果胃气虚弱，水谷不能消化，津液在内枯竭，不能将精微输布到皮毛，气失去卫外功能，血失去荣养功能，不能酝酿毒气直至成形，致使毒气浮沉隐伏，聚散无常，灼烧皮毛，所以产生瘙痒，治疗应当补益气血，调和脾胃，托毒外出，瘙痒必然停止。如果瘙痒不止，抓挠导致皮肤破损、肌肉凹陷的，这是毒气内陷，正气外脱，不久就会死亡。然而先痛后痒，这是正常的征候。因为起初毒气未解化，火势正盛，所以会疼痛；后来脓液形成，毒解火气渐微，所以会瘙痒。但疼痛和瘙痒都不宜过于严重。
《黄帝内经》说：各种疼痛、瘙痒、疮疡都归属于心火。火势炽盛则血热，血热则干涸，干涸则气机阻滞，从而产生疼痛。然而在痘疹初出时就疼痛的，是毒邪尚未发散尽，热毒燎灼肌肤所致。痘疹发出稠密且疼痛的，是毒气盛而血液瘀滞所致。发病六天以前多用发散法，六天以后多用活血法。因干燥阻滞而疼痛的，用水杨汤洗浴。至于痘疮发痒，如果能进食且大便干结的，是邪气内实，正气外虚。疲倦不想吃东西且腹泻的，是正气内虚，邪气外实。更有火邪搏结于肌肤之间，不能立即透出，导致燥灼腠理而发痒的。也有醉酒之人靠近炙烤之物，或衣被过厚而发痒的。更有血液正在流行，却被风寒外束，导致郁滞而发痒的。总体来看，痘色紫赤，饮食能进，气血充足的，其瘙痒属于血热，治疗宜清凉解毒。如果痘色不红活，乳食不进，气血不足的，其瘙痒属于虚寒。然而胃主肌肉，又是气血之源，所以治疗都应适宜调理脾胃、增进饮食、活血化瘀、调匀气机，以避免瘙痒塌陷的祸患。总而言之，疼痛属于实，瘙痒属于虚；热势轻微则痒，热势严重则痛；疼痛和瘙痒都归属于火，但虚实大有不同。
说“虚则痒，痛则实”，是大致而言。空虚则必痒，痒则必塌陷，这是情理上的必然。但是痘色焦紫或灰白的，病情将危重，势必都会瘙痒。可见气虚者作痒，血热者也会作痒，所以贵在起胀之日进行干预，如血热者，先清热凉血；气虚者，先补中益气，则自然没有此患。如果等到病症已成再治疗，必定难以痊愈。然而其人能进食，或大便坚硬，抓破之处又能灌脓，无痘处又发出一批，大小不一，这虽然全部抓破，尚可救治。若在瘙痒之时，其人神志颠倒闷乱，抓破之处不再灌成脓水，或形成坑窟，或即刻干枯变黑，或皮肤自行脱落，又兼呛水呕吐食物，水浆不进，腹泻失音，寒战咬牙，手足厥冷，腹胀啼叫，这些都是死症。然而在初见痘粒粘着且遍身瘙痒的，这是邪气欲出，因皮肤闭密，火气游移往来，所以瘙痒。可引用于伤寒太阳病身痒汗不出者的治疗方法，宜使腠理开通，则邪气得泄，痘起而痒自去，这就是“火郁则发”的含义。若脓液已灌满，势将收敛而瘙痒的，是邪气将散，正气欲复，营卫和阳，所以知道是瘙痒。这与各类疮疖即将痊愈时瘙痒相同，不必忧虑，只需谨记，不要令其搔破流液。在壮灌浆，当血化为水，水化为成脓之时，其毒未化，而浑身瘙痒，爬搔不安的，此为恶候，这与伤寒阳明经中皮肤如虫行般的疼痛同理。这所谓虚风外搏，邪气内强。有痂落后疤痕瘙痒的，因营血耗损，皮肤干燥，是以浮火游行，火甚则痛，火微则痒罢了，治疗宜以清火滋阴为主。大抵出形而皮肉红艳，起发而皮嫩多水的，其后必然瘙痒塌陷，不可不预先调理。
然而瘙痒和塌陷两症相互关联，所以塌陷者，未必不痒；痒者，未必一定塌陷。不塌而痒，痒是可以治疗的；不痒而塌，塌陷是可以治疗的；既塌陷又瘙痒并作的，定然难治。至于抓破如汤火烫伤者，不治。以及气离血散，陷塌发痒而无脓者，不治。
Pain is generally considered excess (Shi, 实), while itching is generally considered deficiency (Xu, 虚). Excess refers to the abundance of pathogenic factors; deficiency refers to the weakness of healthy Qi. Sores and rashes are caused by Fire. When Fire is vigorous, pain occurs; when Fire is mild, itching occurs. Therefore, constant pain indicates an excess of pathogenic factors. The toxicity of smallpox erupts between the skin, hair follicles, muscles, and flesh. It is constrained by Qi and moistened by Blood, fermenting its toxicity until transformation. If Healthy Qi is complete and unrelenting, and the toxic vapors have transformed but not yet fully formed, stagnation leads to pain; this is the normal state. When the toxicity transforms into pus and takes shape, the pain ceases on its own. However, severe pain resembling knife cuts or needle pricks, accompanied by loud crying and wailing, indicates damage to the skin and flesh, meaning the body cannot withstand the toxicity. This is a variation of pain, representing a "bad syndrome" (Huai Zheng, 坏症) with poor prognosis. Constant itching indicates deficiency of Healthy Qi. The *Classic* states: "The Stomach is the sea of water and grain, the great source of the six Fu organs." Flavors enter the mouth and are stored in the Stomach to nourish the five Zang organs. If Stomach Qi is deficient, water and grain fail to transform, internal fluids dry up, and essence cannot be transported to the skin and hair. Qi loses its defensive function, and Blood loses its nourishing function, failing to ferment toxic vapors into formation. Consequently, toxic vapors float, sink, hide, and vanish suddenly, burning the skin and hair, causing itching. Treatment should tonify Qi and Blood, harmonize the middle, and support the interior to expel toxins; the itching will then cease. If itching persists, leading to scratching that destroys the skin and leaves muscle pits, this indicates internal sinking of toxic vapors and external collapse of Healthy Qi, leading to death shortly thereafter.
However, pain preceding itching is a normal pattern. Initially, the toxin has not resolved or transformed, and Fire is vigorous, causing pain. Later, pus forms, the toxin resolves, and Fire energy gradually diminishes, causing itching. Nevertheless, neither pain nor itching should be excessive. The *Classic* states: "All pain, itching, sores, and ulcers belong to Heart Fire." Vigorous Fire causes blood heat; heat causes dryness; dryness causes Qi stagnation, resulting in pain. Pain upon initial eruption indicates that the pathogen has not been fully dispersed, and heat-toxicity is scorching the skin and muscles. Dense eruptions accompanied by pain indicate abundant toxicity and blood stasis. Before the sixth day, dispersing methods are mostly used; after the sixth day, blood-invigorating methods are mostly used. For pain due to dryness and stagnation, bathing with Shuoyang Decoction (Water Willow Decoction) is appropriate. Regarding smallpox itching: if the patient can eat and has hard stools, it indicates internal excess of pathogenic factors and external deficiency of Healthy Qi. If the patient is fatigued, lacks appetite, and has diarrhea, it indicates internal deficiency of Healthy Qi and external excess of pathogenic factors. Additionally, Fire pathogens combusting between the skin and muscles, unable to emerge immediately, cause dryness and burning of the interstices (Cou Li, 腠理), leading to itching. There are also cases where drunk individuals approach heat sources, or wear heavy clothing/bedding, causing itching. Furthermore, when Blood is circulating freely but is bound externally by Wind-Cold, stagnation leads to itching. Generally, if the smallpox color is purple-red, the patient can eat, and Qi and Blood are sufficient, the itching belongs to Blood Heat; treatment should focus on clearing heat and detoxifying. If the color is not red and vibrant, the patient refuses milk/food, and Qi and Blood are insufficient, the itching belongs to Deficiency-Cold. Since the Stomach governs muscles and is the source of Qi and Blood, treatment should regulate the Spleen, promote appetite, invigorate Blood, and harmonize Qi to avoid complications of itching and collapsing. In summary, pain is excess, itching is deficiency; mild heat causes itching, severe heat causes pain; both pain and itching belong to Fire, but their excess and deficiency differ significantly.
Saying "deficiency causes itching, excess causes pain" is a generalization. Emptiness inevitably causes itching, and itching inevitably leads to collapsing; this is logically inevitable. However, if the lesions are scorched-purple or ash-white, the condition is critical, and itching is inevitable. Thus, Qi deficiency causes itching, and Blood Heat also causes itching. Therefore, intervention at the time of swelling and rising is crucial: for Blood Heat, clear heat and cool Blood first; for Qi deficiency, tonify the Middle and boost Qi first. Then these complications will naturally be avoided. If treatment is delayed until symptoms are established, cure will be difficult. However, if the patient can eat or has hard stools, and scratched areas fill with pus again, while new eruptions appear elsewhere varying in size, even if all are scratched open, rescue is still possible. Conversely, during itching, if the patient is confused and restless, scratched areas do not fill with pus, form pits, become dry and black, or shed skin, accompanied by choking on water/food, inability to ingest liquids, diarrhea, loss of voice, chills with teeth grinding, cold extremities, abdominal distension, and crying, these are all fatal signs. However, if initially the lesions are sticky and the whole body itches, this indicates the pathogen desires to exit but is blocked by tight skin, causing wandering Fire, hence itching. This can be treated similarly to Sun-Yang Syndrome (Taiyang Disease) in Cold Damage presenting with body itching and no sweat: open the interstices to allow pathogen release; as the lesions rise, itching subsides. This embodies the principle of "dispersing stagnant Fire." If pus is fully formed and contraction begins, causing itching, this indicates the pathogen is scattering and Healthy Qi is recovering, harmonying Ying and Wei and Yang. This is similar to itching in other sores and boils nearing recovery; there is no need for worry, just remember not to scratch them open. During the stage of vigorous filling, when Blood transforms into fluid and fluid into pus, if the toxicity has not transformed and the whole body itches restlessly, this is a malignant sign. This is discussed similarly to the sensation of insects crawling in the skin in Yang-Ming Channel Cold Damage. This represents external assault by deficient Wind and internal strength of pathogenic factors. Itching of scars after scab fall is due to consumption of Ying Blood and dry skin, causing wandering floating Fire; severe Fire causes pain, mild Fire causes itching. Treatment should primarily clear Fire and nourish Yin. Generally, if eruptions are bright red and fleshy, or if they rise tenderly with much fluid, itching and collapsing will inevitably follow; preventive regulation is essential.
Itching and collapsing are causally linked; thus, collapsing does not necessarily mean itching, and itching does not necessarily mean collapsing. Itching without collapsing is treatable; collapsing without itching is treatable; simultaneous collapsing and itching is definitely difficult to treat. Scratching open like scalds is untreatable. Collapse with itching and no pus, indicating separation of Qi from Blood, is untreatable.