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Pruritus caused by internal injury may be either excess or deficiency; pruritus caused by external contraction is invariably due to the failure of the exterior pathogenic factor to be expelled through sweating. Therefore, in Taiyang disease (disease pattern resulting from invasion of the Taiyang channel), there are clauses mentioning pruritus, and in Yangming disease (disease pattern resulting from invasion of the Yangming channel), there are clauses describing a sensation like insects crawling on the skin. These are all because the exterior pathogenic factor has no outlet, so pruritus occurs solely due to incomplete sweating. When wind-cold is present at the exterior, body pain results; when wind-heat is present at the exterior, pruritus results. In summary, when yang pathogens are constrained and stagnant at the muscle layer and cannot be released through sweating, the skin becomes itchy. For pruritus associated with Taiyang disease, Qianghuo Baidu San (Decoction of Notopterygium and Angelica Pubescens to Overcome Toxins) is used. If the pruritus is associated with Yangming disease, Gange Fangfeng Tang (Kudzu Root and Saposhnikovia Decoction) is used. For pruritus associated with Shaoyang disease (disease pattern resulting from invasion of the Shaoyang channel), Chaihu Fangfeng Tang (Bupleurum and Saposhnikovia Decoction) is used. The *Yuan Bing Shi* states that when the couli (skin pores and interstices) are closed and dense, and yang qi is constrained and stagnant without being able to dissipate, pruritus develops. Therefore, Zhang Zhongjing used Mahuang Guizhi Ge Ban Tang (Half-Dose Decoction of Ephedra and Cinnamon Twig) to disperse the exterior pathogenic factor using acrid-warm herbs. The *Yangming Pian* chapter says, "This is due to long-standing deficiency." This refers to individuals whose yuan qi (original qi) has been deficient for a long time and who lack sufficient fluids; upon contracting an external pathogen, they cannot generate sweat to expel the pathogen due to this chronic deficiency. The treatment should focus on dispersing the exterior pathogen, not on using tonifying medicines simply because of chronic deficiency. The *Huoren* (referring to *Huoren Shu*) erroneously treated this with Shu Fu Tang (Atractylodes and Aconite Decoction) and Huangqi Jianzhong Tang (Astragalus Decoction to Establish the Middle), which caused significant harm.

When Taiyang disease persists for eight or nine days, the symptoms resemble malaria: fever and aversion to cold, with heat predominating over cold. The patient does not vomit, and bowel movements and urination are normal, indicating the condition seems stable. The episodes occur two or three times a day. If the pulse is slightly slow and relaxed, it indicates impending recovery. If the face appears flushed with redness, recovery is not imminent because slight sweating has not occurred, leading to inevitable pruritus. In such cases, Guizhi Mahuang Ge Ban Tang (Half-Dose Decoction of Cinnamon Twig and Ephedra) is appropriate.

In Taiyang disease persisting for eight or nine days, described as resembling malaria, the prerequisite conditions for potential recovery are the absence of vomiting, normal bowel and bladder function, and a slightly slow and relaxed pulse. If the face instead shows redness, it indicates that the exterior pathogenic factor has not yet dissipated, and pruritus will likely occur; therefore, methods to disperse the exterior pathogen should be employed.

In Yangming disease, profuse sweating is the norm. If there is unexpectedly no sweating, and the body feels as if insects are crawling within the skin, this is due to long-standing deficiency.

Yangming disease typically involves profuse sweating. The current presentation of no sweating, accompanied by a sensation of external pathogens invading the skin causing a crawling feeling, stems from inherent weakness of yuan qi, which fails to generate sweat to expel the pathogen. No specific formula is prescribed here, but the intent to disperse the exterior pathogen and tonify yuan qi is implicit.

Qianghuo Baidu San: See section on Fever.

Gange Fangfeng Tang
Ingredients: Gan Ge (Puerariae Radix / Kudzu Root), Fang Feng (Saposhnikoviae Radix / Saposhnikovia Root), Jing Jie (Schizonepetae Spica / Schizonepeta Spike), Gan Cao (Glycyrrhizae Radix et Rhizoma / Licorice Root).

For pruritus due to Taiyang disease, rather than using Mahuang Guizhi Ge Ban Tang, Qianghuo Baidu San is used. For pruritus due to Yangming disease, rather than using the original Gange Fangfeng Tang formula, this modified version is used, because the exterior pathogen is accompanied by fire stagnation.

Chaihu Fangfeng Tang
Ingredients: Chai Hu (Bupleuri Radix / Bupleurum Root), Fang Feng (Saposhnikoviae Radix / Saposhnikovia Root), Jing Jie (Schizonepetae Spica / Schizonepeta Spike), Gan Cao (Glycyrrhizae Radix et Rhizoma / Licorice Root).

For pruritus due to Taiyang and Yangming diseases, the previous two formulas are used. For pruritus due to Shaoyang disease, this formula is used. For pruritus due to combined disease of the Three Yang channels (Taiyang, Yangming, and Shaoyang), the three formulas should be combined.

Guizhi Mahuang Ge Ban Tang: See section on Fever.