Arnebia Root / Gromwell Root Classic Formulas

Primary Actions

Clears Heat, cools Blood, and resolves Toxicity — Blood-level Heat with skin rashes, erythema, and purpura where the rash has not fully erupted; the cold nature cools Heat in the Blood and the sweet taste enters the Liver Blood; classic indication for measles, scarlet fever, and maculopapular rashes from Heat toxin; combined with Da Qing Ye, Lian Qiao, and Gan Cao
Promotes the eruption of rashes and measles — facilitates incomplete measles eruption by venting Heat toxin to the skin surface; combined with Chan Tui, Niu Bang Zi, and Bo He; the purple color of the herb root and its skin-level action are the TCM observational basis for this use
Resolves Toxicity for skin lesions — topical and internal use for burns, eczema, boils, carbuncles, and infected sores; the cooling action reduces Heat swelling and promotes tissue healing; considered the foremost TCM herb for fire burns (火伤) in classical surgery texts

Zi Cao Hua Zhi Gao (紫草化治膏) — classical topical formula for burns, eczema, and infected skin ulcers; Zi Cao steeped in sesame oil alongside Dang Gui, Bai Zhi, and other herbs; still used in Chinese dermatology and the foundation of many modern TCM topical skin preparations
Zi Cao San (紫草散) — for measles and rash that fails to erupt fully; Zi Cao combined with Niu Bang Zi, Chan Tui, Bo He, and Gan Cao; targets Blood-Heat obstruction that delays rash eruption
Xiao Er Hua Ban Tang — pediatric formula for Heat rash with Blood-level involvement; Zi Cao as the primary Blood-cooling agent combined with fever-clearing herbs

Shen Nong Ben Cao Jing (middle class): 'Zi Cao (紫草) — bitter, cold; enters Heart channel; clears Heart Fire, cools Blood, resolves Toxicity for sores; the purple root color indicates its Blood-level action; used for skin diseases of Heat-toxic origin'
Ben Cao Gang Mu (Li Shizhen): 'Zi Cao enters the Blood — sweet, cold; Heart governs Blood, Liver stores Blood; this herb enters both; the purple color reflects its action on Blood level; for maculae, erythema, measles rash; both internal and topical applications documented'