Xiao Feng San and Siwu Xiao Feng San for Skin Pruritus
Spring is the high-incidence season for allergic skin diseases and for skin itching in cancer and chronic lung disease patients. TCM treatment of such pruritus has two classical experienced formulas: Xiao Feng San (Wind-Dispersing Powder) and Siwu Xiao Feng San (Four-Ingredient Wind-Dispersing Powder). Xiao Feng San comes from Waike Zhengzong (Orthodox Manual of External Medicine), and Siwu Xiao Feng San from Yizong Jinjian (Golden Mirror of the Medical Tradition).Xiao Feng San consists of Jingjie (Herba Schizonepetae), Fangfeng (Radix Saposhnikoviae), Chantui (Periostracum Cicadae), Niubangzi (Fructus Arctii), Cangzhu (Rhizoma Atractylodis), Kushen (Radix Sophorae Flavescentis), Shigao (Gypsum), Zhimu (Rhizoma Anemarrhenae), Danggui (Radix Angelicae Sinensis), Shengdi (Radix Rehmanniae), and Humaren (Semen Sesami) each 2 qian (about 6g today), plus Mutong (Caulis Akebiae) and Gancao (Radix Glycyrrhizae) each 1 qian (about 3g today). Waike Zhengzong says of it: "Treats wind-dampness invading and pouring into the blood vessels, causing scabies and incessant itching, as well as wind-heat rashes in adults and children, cloud-like patches all over the body that come and go; effective in all."Today this formula is commonly used to treat rubella and eczema caused by wind-heat or wind-dampness invading the body or pouring into the blood vessels, presenting as red skin eruptions or cloud-like patches all over, itching, exudate after scratching, and a white or yellow tongue coating. Acute skin diseases such as urticaria, allergic dermatitis, paddy-field dermatitis, drug dermatitis, neurodermatitis, acute glomerulonephritis, and spring catarrhal conjunctivitis presenting the above symptoms may all be treated with this formula.Siwu Xiao Feng San consists of Shengdi 3 qian (about 9g), Danggui 2 qian (about 6g), Jingjie and Fangfeng each 1.5 qian (about 4.5g), Chishao (Radix Paeoniae Rubra), Bohe (Herba Menthae), Chantui, and Baixianpi (Cortex Dictamni) each 1 qian (about 3g), plus Duhuo (Radix Angelicae Pubescentis) and Chaihu (Radix Bupleuri) each 7 fen (about 2.1g). This formula is modified on the basis of Siwu Tang (Four-Substance Decoction) and has the actions of cooling and nourishing blood, dispersing wind, and clearing heat. It is suitable for rubella and hidden rashes in patients with blood-deficiency constitution induced by external pathogens, presenting as migrating pruritus over the body, bright-red itching rashes, and habitual dizziness and fatigue.This formula removes the acrid-drying Chuanxiong (Rhizoma Chuanxiong) from Siwu Tang (Shengdi, Chishao, Danggui, Chuanxiong) and adds Jingjie, Fangfeng, Bohe, Chantui, Duhuo, and Chaihu. Siwu Tang is a famous blood-nourishing formula, so this prescription is especially suitable for patients with weak constitution: chronic urticaria, drug dermatitis, allergic dermatitis, and senile pruritus.Skin diseases call for avoiding spicy, greasy, fishy, alcohol, tobacco, strong tea, and coffee; patients using the above two formulas should observe these dietary restrictions. Modern pharmacological studies show that both formulas have anti-allergic and some antibacterial effects, which may be their internal mechanism for treating pruritus.