一、丹毒之原因
小儿一岁以内，身发赤游风者，皮如涂丹之状，而其原多由血中热毒之壅滞，故谓之丹毒。溯其远因，
胎儿先天血中之伏毒，总由妊母血热流于胎中，热毒蕴于腠理，此生下之后，发动而宣泄，即为丹毒，亦谓
之游丹。以其游走甚速，重者顷刻可以致命也。有时发动之因，为乳母好酒嗜辛，喜啖炙爆，或烘晒热
衣，即与包裹，柔嫩肌肤，感受热毒所致。发于四肢者易治，由四肢入腹入囊，皆为难疗也。故婴孩初生，
最宜服解毒之药，后天饮食，更须令乳母食清淡之味。起居方面，亦小心谨慎，则丹
毒自无由发生，即发生亦不甚为患矣。
二、丹毒之症状
丹毒之轻者，多发于臀部及四肢，皮肤略有浮胀 赤之状，
或片片如红云，愈重者色愈紫赤，胀亦愈坚，尤重者热毒凝壅，坚硬成块，谓之丹瘤。大凡发于头面胸背者
重，而能渐退以走入四肢者亦尚易治，如发于四肢而倏忽走入头面胸背者必不易治，发时身如火灼，烦躁
胀闷者亦重，古人谓入心必死。盖热毒最忌走窜，若顷刻蔓延，壅塞心经，心失其主，必为不救也。
三、丹毒之治法
丹毒之原因，既由于血中热毒之壅滞，故其治法总不外凉血解毒，初起之轻者，臀部或足部有紫胀之状，
可以针沿足之两旁、腿之两侧微刺之，挤去瘀紫之血，胀必渐退。较甚者初刺无
血，仅流黄色之汁，宜再刺之，使见血为度。如刺后多时，胀复，作者，则再刺一次，数日之后，胀即松而丹
即退。此种刺去恶血之法，盖即所以泄去血中之热毒而不使壅滞也。重者结块瘀胀，
宜砭去恶血，如在头面等处，则不可砭，外治之药，用朴硝、大黄、青黛为末，新汲水调敷，或芭蕉根
捣汁涂，干则再涂，冬月畏冷，则炖稍温涂上、或用井底泥涂之亦妙。无论赤白丹毒，若
用寒凉之品，涂之不效者，将伏龙肝为极细末，以熟鸡子黄熬油调涂之，必可见效（按寒凉之品既不效，
必非完全热毒，盖小儿皮肤娇嫩，其接触尿片之处，因摩擦而发肿如丹者亦有之，则宜
用此法涂治，或用密陀僧研细末调白蜜浓茶涂之亦可），内服之方，宜犀角解毒饮、蓝叶散之类。
附方
（一）犀角解毒饮 治小儿赤游风，发于头面四肢，皮肤赤而肿，色若涂朱，游走不定者。
犀角 牛蒡子（炒） 荆芥穗 防风 连翘（去心） 金银花 赤芍药 生甘草 川黄连 生地黄（各等分）
灯芯为引，水煎服，或研细末炼蜜为丸，名犀角解毒丸。
（二）蓝叶散 治小儿月内发丹毒。
蓝叶（一两） 黄芩 犀角屑 川大黄（锉，微炒） 柴胡（去芦） 栀子
仁（各一分） 川升麻 石膏（各一分五厘） 甘草（五厘）
研为粗未，每服一钱，清水一小盏，煎至五分，去滓，加竹沥五勺，再煎二三沸，不拘时温服。
元气怯弱者去大黄。
I. Etiology of Erysipelas (Dan Du)
In infants under one year of age, the appearance of "Chi You Feng" (Red Roaming Wind, a condition characterized by red, wandering skin lesions), where the skin resembles applied cinnabar, is primarily caused by the stagnation of heat-toxin in the blood; hence it is called Dan Du (Erysipelas). Tracing back to its remote causes, the latent toxin in the fetal blood generally stems from the mother's blood-heat flowing into the fetus. The heat-toxin accumulates in the Cou Li (the interstitial spaces between the skin and muscles), and after birth, when this latent toxin activates and exudes, it manifests as Dan Du, also known as You Dan (Roaming Dan). Because it spreads rapidly, severe cases can be fatal within moments. Sometimes, the triggering factors include the wet nurse's preference for alcohol and spicy foods, consumption of roasted or fried items, or wrapping the infant in clothes heated by sun-drying, causing the tender skin to contract heat-toxin. Lesions appearing on the limbs are easier to treat, whereas those spreading from the limbs to the abdomen or scrotum are difficult to cure. Therefore, immediately after birth, infants should best take detoxifying medicines. Regarding postnatal diet, the wet nurse must consume light and bland food. With careful attention to daily living habits, Dan Du will have no opportunity to occur; even if it does, it will not cause significant harm.
II. Symptoms of Erysipelas
Mild cases of Dan Du mostly occur on the buttocks and limbs, presenting with slight swelling and redness of the skin, or patchy appearances resembling red clouds. The more severe the case, the deeper the purple-red color and the firmer the swelling. In particularly severe cases, heat-toxin condenses and stagnates, forming hard masses, termed Dan Liu (Erysipelas Tumor). Generally, lesions appearing on the head, face, chest, and back are serious; however, if they gradually recede and move toward the limbs, they remain relatively easy to treat. Conversely, if lesions start on the limbs but suddenly spread rapidly to the head, face, chest, and back, they are certainly difficult to treat. When accompanied by body heat feeling like burning, irritability, distension, and stifling sensation, the condition is also severe. Ancient texts state that if the pathogen enters the Heart, death is inevitable. This is because heat-toxin is most feared for its tendency to wander and spread; if it spreads instantly, obstructing the Heart Meridian and causing the Heart to lose its governing function, rescue becomes impossible.
III. Treatment Methods for Erysipelas
Since the etiology of Dan Du lies in the stagnation of heat-toxin in the blood, the treatment principle invariably involves cooling the blood and resolving toxicity. For mild initial cases presenting with purple swelling on the buttocks or feet, needles may be used to make superficial pricks along both sides of the foot and the lateral aspects of the legs to drain the stasis-purple blood, after which the swelling will gradually subside. In more severe cases where initial pricking yields no blood but only yellow fluid, repeated pricking should continue until blood appears. If the swelling recurs long after pricking, another session of pricking is recommended; after several days, the swelling will soften and the erysipelas will recede. This method of draining evil blood serves to vent the heat-toxin from the blood and prevent stagnation. For severe cases with nodular, stasis-filled swelling, Bian Shi (stone lancet) therapy should be used to remove evil blood; however, this is contraindicated on the head and face. For external treatment, use powder made from Xiao Ming (Natrii Sulfas), Da Huang (Rhei Radix et Rhizoma), and Qing Dai (Indigo Naturalis), mixed with fresh well-water for application, or apply juice extracted from crushed Ba Jiao Gen (Musa Basjoo Root), reapplying as it dries. In winter, to avoid cold, warm the mixture slightly before application, or applying mud from the bottom of a well is also effective. Whether for Chi Dan (Red Erysipelas) or Bai Dan (White Erysipelas), if topical cooling agents prove ineffective, consider using Fu Long Gan (Caulis Forni, i.e., Hearth Earth) ground into an ultra-fine powder, mixed with oil rendered from cooked egg yolk for application, which will surely show efficacy. (Note: If cooling agents fail, it indicates that the condition may not be purely heat-toxin; for instance, infants with delicate skin may develop erysipelatoid swelling due to friction from diaper contact, in which case this method is suitable. Alternatively, Mi Tuo Seng (Litharge) ground fine and mixed with white honey or strong tea can also be used.) For internal administration, formulas such as Xi Jiao Jie Du Yin (Rhino Horn Detoxification Decoction) or Lan Ye San (Isatis Leaf Powder) are appropriate.
Attached Formulas
(1) Xi Jiao Jie Du Yin (Rhino Horn Detoxification Decoction)
Indications: Pediatric Chi You Feng (Red Roaming Wind) manifesting on the head, face, and limbs, with red and swollen skin resembling applied vermilion, moving unpredictably.
Ingredients: Xi Jiao (Rhinocerotis Cornu), Niu Bang Zi (Arctii Fructus, stir-fried), Jing Jie Sui (Schizonepetae Spica), Fang Feng (Saposhnikoviae Radix), Lian Qiao (Forsythiae Fructus, heart removed), Jin Yin Hua (Lonicerae Japonicae Flos), Chi Shao Yao (Paeoniae Radix Rubra), Sheng Gan Cao (Glycyrrhizae Radix et Rhizoma Recens), Chuan Huang Lian (Coptidis Rhizoma), Sheng Di Huang (Rehmanniae Radix Recens). All ingredients in equal parts.
Preparation: Use Deng Xin Cao (Junci Medullia) as a guide ingredient; decoct in water and take orally. Alternatively, grind into fine powder and form pills with refined honey, named Xi Jiao Jie Du Wan (Rhino Horn Detoxification Pill).
(2) Lan Ye San (Isatis Leaf Powder)
Indications: Dan Du occurring in infants within their first month of life.
Ingredients: Lan Ye (Isatidis Folium, 1 liang), Huang Qin (Scutellariae Radix), Xi Jiao Xie (Rhinocerotis Cornu Scraps), Chuan Da Huang (Rhei Radix et Rhizoma, sliced, lightly stir-fried), Chai Hu (Bupleuri Radix, radix removed), Zhi Zi Ren (Gardeniae Semen, all 1 fen); Chuan Sheng Ma (Bupleuri Radix? Note: Text says Chuan Sheng Ma, likely Cimicifugae Rhizoma or similar ascending herb, usually Sheng Ma), Shi Gao (Gypsum Fibrosum, both 1 fen 5 li), Gan Cao (Glycyrrhizae Radix et Rhizoma, 5 li).
Preparation: Grind into coarse powder. Take 1 qian per dose, decoct with one small cup of clear water until reduced to 0.5 cup, strain the dregs, add Zhu Li (Bambusae Caulis in Taenia, 5 spoons), boil for two or three more boils, and take warm at any time. For patients with weak Yuan Qi (Primary Vitality), remove Da Huang.