Huodan (Fire Erysipelas) is caused by the reckless movement of Heart Fire and Wind-Heat invading the Sanjiao (Triple Burner), thus manifesting on the surface of the skin. It presents in dry and wet forms, with variations in red and white colors. The dry type manifests as red skin resembling cloud patches, raised wind-corns (urticarial papules), accompanied by itching and fever; this belongs to Fire in the Heart and Liver meridians, and should be treated by cooling the Heart and purging the Liver, resolving macules, and detoxifying, using Huaban Jiedu Tang (Macule-Resolving Detoxification Decoction). The wet type appears mostly yellowish-white, varying in size, weeping fluid and causing erosion, often with significant pain; this belongs to Damp-Heat in the Spleen and Lung meridians, and should be treated by clearing the Lungs, purging the Spleen, and removing Dampness, using Weiling Tang (Stomach-Purging Decoction). If it occurs on the waist and hypochondrium due to reckless Liver Fire, it is called Chanyao Dan (Waist-Coiling Erysipelas), treated with Chaihu Qinggan Tang (Bupleurum Liver-Clearing Decoction). Externally apply Baiye San (Cypress Leaf Powder) or Ruyi Jinhuang San (Ruyi Golden Yellow Powder).

Huaban Jiedu Tang (Macule-Resolving Detoxification Decoction)
Composition: Shigao (Gypsum Fibrosum), Xuanshen (Scrophulariae Radix), Zhimu (Anemarrhenae Rhizoma), Lianqiao (Forsythiae Fructus), Huanglian (Coptidis Rhizoma), Shengma (Cimicifugae Rhizoma), Niubangzi (Arctii Fructus), etc., with Gancacao (Glycyrrhizae Radix et Rhizoma) used in a higher proportion.
Indications: Treats Huodan caused by Wind-Heat attacking upward from the Sanjiao, spreading over the whole body with itching and pain.
Prescription: Xuanshen, Zhimu, Shigao, Renzhonghuang (Human Feces Carbonized), Huanglian, Shengma, Lianqiao, Niubangzi (each equal parts), Gancacao (2 grams).
Administration: Water 600 ml, Danzhuye (Lophatheri Herba) 20 leaves, decocted to 240 ml, taken at any time.

Chushi Weiling Tang (Damp-Removing Stomach-Purging Decoction)
Composition: Gancacao, Houpo (Magnoliae Officinalis Cortex), Chenpi (Citri Reticulatae Pericarpium), Cangzhu (Atractylodis Rhizoma), Baizhu (Atractylodis Macrocephalae Rhizoma), Zexie (Alismatis Rhizoma), Zhuling (Polyporus), Fangfeng (Saposhnikoviae Radix), Huashi (Talcum), Zhizi (Gardeniae Fructus), Mutong (Akebiae Caulis), Bo Gui (Cinnamomi Cortex), Chi Fuling (Poria Cocos with Red Mycelium).
Indications: Treats Huodan with erosion and pain caused by Damp-Heat stagnation in the Spleen and Lung meridians.
Prescription: Fangfeng, Cangzhu, Baizhu, Chi Fuling, Chenpi, Houpo, Zhuling, Zhizi, Mutong, Zexie, Huashi (each 3 grams), Gancacao, Bo Gui (each 1 gram).
Administration: Water 600 ml, Dengxincao (Junci Medullia) 20 stems, decocted to 240 ml, taken before meals.

Baiye San (Cypress Leaf Powder)
Composition: Cebaiye (Platycladi Cacumen), Qiuyinfen (Earthworm Excrement), Chidou (Vigna Angularis Semen), Dahuang (Rhei Radix et Rhizoma), Huangbai (Phellodendri Cortex), Qingfen (Calomelas).
Indications: Treats Huodan caused by excessive Fire in the Sanjiao, presenting with itching or pain, spreading over the whole body.
Prescription: Cebaiye (stir-fried until yellow and powdered, 15 grams), Qiuyinfen (preferably from leek fields), Huangbai, Dahuang (each 15 grams), Chidou, Qingfen (each 9 grams).
Administration: Grind all ingredients into fine powder, mix with fresh well water, and apply externally.

For Chanyao Huodan (Waist-Coiling Fire Erysipelas), use one banknote, burn it to ash while preserving its medicinal nature, grind into fine powder, mix with rice vinegar to a thin consistency, dip a chicken feather in the mixture, and apply to the affected area three times a day for cure. Avoid stimulating foods (Fa Wu).

Ruyi Jinhuang San (Ruyi Golden Yellow Powder) (See Swelling and Ulcer Section)
Indications: Treats Huodan regardless of new or old onset, with itching and pain. Mix with fresh well water for external application; Indigo juice is also effective.