水痘重者，亦类伤寒之状，身热二三日而出，形与正痘不同。凡疮皮不薄，根起成
晕，其头渐渐，赤肿变白而黄，有脓而瘥迟者，谓之大痘，此里证发于脏也，若疮皮薄
如水，泡顶亮如珠。或破即为干靥，出无渐次，根脚全散，而色白或淡红，冷冷有水浆
者，谓之肤疮，又名水痘。此表症发于腑也，类同疹子，较疹更轻，故发热即出，出
后即消，易出易靥。其始不宜过发，过发则变为疮，终不宜燥湿，燥湿反致难靥，惟用
轻剂解之，如无他苦，不必服药，无伤性命者也。然方书有云∶凡水痘夹黑不出者，或
全黑色者，十死一生，书载虽有是条，而实未见有是痘，大抵原系正痘之恶者，故能伤
人，而人误认作水痘耳。
斑多行于天行时气之病，壮热不已，大便秘结，是以热留胃中，胃主肌肉，乃发为
斑者，胃中留热，而为里症也。不可与疹同治，而妄用发散之剂，以致反增危剧，宜人
参白虎汤，去人参加玄参、生地之类主之。切忌五辛糯米，助胃助火之物。便秘者，以
三黄丸利之。赤斑者，十死一生。黑斑者，十死生。然更有阴寒内伏，而逼无根失守之
火，浮于肌表，而为斑点者，此胃气极虚之证，若服寒药，立见危殆，不可不知。
凡痘始终用药诸要悉具补遗门用药活法条内参看。
水痘病情较重的，症状也类似伤寒，身体发热二三天后出疹，形态与真正的痘疮不同。凡是痘皮不薄，根部隆起并伴有红晕，痘头逐渐红肿变白再转黄，有脓液且愈合迟缓的，称为大痘，这是里证，病发于五脏；如果痘皮薄如水泡，顶端明亮如珍珠，或者破裂后迅速结成干痂，出疹没有先后次序，根部散漫无定形，颜色白或淡红，冷凉且有水浆的，称为肤疮，又名水痘。这是表证，病发于六腑，类似于麻疹，比麻疹更轻，所以发热即出疹，出疹后即消退，容易发出也容易结痂。初期不宜过度使用发汗解表的药物，过度发汗则会转变为严重的疮疡；后期也不宜过度燥湿，过度燥湿反而导致难以结痂，只需用轻清的药剂来解除病邪，如果没有其他痛苦，不必服药，也不会危及生命。然而医书上有记载说：凡是水痘夹杂黑色不出者，或全呈黑色的，十死一生，书中虽然有这样的条文，但实际上从未见过这种痘症，这大抵是原本就是痘疮中恶劣的类型，所以能伤人，而人们误将其认作水痘罢了。
斑疹多发生于天行时气（流行性传染病）的疾病中，持续高热不退，大便秘结，这是因为热邪滞留于胃中，胃主肌肉，因而发为斑疹，这是胃中留热所致的里证。不可与麻疹同治，若妄用发散的药物，会导致病情反而加重危急，适宜用人参白虎汤，去掉人参加入玄参、生地黄等药物为主进行治疗。切忌食用五辛（葱、蒜、韭、薤、兴渠）和糯米等助胃火的食物。大便秘结的，用三黄丸通利大便。出现赤色斑疹的，十死一生。出现黑色斑疹的，十死一生。然而还有因阴寒内伏，逼迫无根失守的虚火浮越于肌表，从而形成斑点的，这是胃气极度虚弱的证候，如果服用寒凉药物，立刻就会见到危险，这一点不可不知道。
凡是痘疮治疗过程中始终用药的要领，全部详见《补遗门》中的“用药活法”条目内参考查看。
For severe cases of chickenpox (Shuidou), the symptoms resemble those of Cold Damage (Shanghan). The body fever persists for two to three days before the eruption appears, and its morphology differs from that of smallpox (Zhengdou). If the vesicle wall is not thin, the base is elevated with an areola, the head gradually becomes red and swollen, then turns white and yellow, contains pus, and heals slowly, it is called "Large Pox" (Da Dou). This represents a Interior Syndrome (Li Zheng) originating from the Zang organs. Conversely, if the vesicle wall is thin like water, the apex is bright like a pearl, or it dries into a crust immediately upon rupture, erupts without order, has a diffuse base without distinct borders, appears white or pale red, feels cool, and contains serous fluid, it is called "Skin Sore" (Fu Chuang), also known as Chickenpox (Shuidou). This represents an Exterior Syndrome (Biao Zheng) originating from the Fu organs. It resembles measles (Zhenzi) but is milder; thus, fever is accompanied by immediate eruption, which subsides quickly after appearing, making it easy to erupt and easy to crust over. Initially, excessive diaphoresis (inducing sweating) should be avoided; excessive sweating may transform the condition into a severe sore. Finally, excessive drying of dampness should be avoided, as it may hinder crusting. Only mild agents should be used to resolve the pathogen. If there are no other distressing symptoms, medication is unnecessary, and life will not be endangered. However, medical texts state: "In cases where chickenpox is mixed with black color and fails to erupt, or is entirely black, ten out of ten die." Although such entries exist in books, this type of pox has practically never been seen. These are likely malignant forms of true smallpox that cause death, which people mistakenly identify as chickenpox.
Macules/Purpura (Ban) often occur in epidemics caused by Heavenly Qi (Tianxing Shiqi). Patients suffer from persistent high fever and constipation. This indicates heat retention in the Stomach. Since the Stomach governs the muscles, the retained heat manifests as macules/purpura, constituting an Interior Syndrome due to Stomach heat. This must not be treated identically to measles; using dispersing agents recklessly can worsen the condition critically. The appropriate treatment is Ren Shen Bai Hu Tang (Ginseng White Tiger Decoction), modified by removing Ginseng and adding Xuan Shen (Scrophulariae Radix) and Sheng Di Huang (Rehmanniae Radix). One must strictly avoid Five Acrids (Wu Xin: garlic, chives, leeks, scallions, and asafoetida) and glutinous rice, as these foods aid Stomach fire. For constipation, San Huang Wan (Three Yellow Pill) should be used to promote bowel movement. Red macules/purpura indicate a prognosis of ten deaths to one survival. Black macules/purpura indicate a similar fatal prognosis. Furthermore, there are cases where Yin-cold lies hidden internally, forcing rootless and unanchored floating fire to rise to the muscle surface, causing macular eruptions. This is a syndrome of extreme deficiency of Stomach Qi. Administering cold-natured medicines in such cases will lead to immediate danger; this must be clearly understood.
All essential principles regarding medication throughout the course of treating smallpox are detailed in the section "Flexible Application of Medications" within the "Supplementary Volume" (Buyi Men); please refer to that section.