TCM Properties

Traditional Use

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

Clears Damp-Heat in the lower Jiao — jaundice and urinary dysfunction with Damp-Heat etiology; less common use compared to the Blood-cooling and skin-rash indications
Topical anti-inflammatory for dermatological conditions — eczema, psoriasis, and contact dermatitis; the purple shikonin pigment is incorporated into oil-based topical preparations (Zi Cao oil) with sesame oil or petroleum jelly carrier

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'

Shikonin and acetylshikonin (hydroxynaphthoquinones) — the principal purple-red pigments and major bioactive compounds; naphthoquinone class; responsible for the intense red-violet root color; anti-inflammatory, anticancer, antimicrobial, and wound-healing activity
Alkanin — the enantiomer of shikonin found in Arnebia euchroma; similar pharmacological profile to shikonin; the two naphthoquinones together account for the majority of bioactivity
β-acetylshikonin, β-hydroxyisovalerylshikonin, isobutyrylshikonin (shikonin ester derivatives) — multiple naphthoquinone esters with varying bioactivity profiles isolated from root extracts
Pyrrolizidine alkaloids (low level) — present in trace amounts in Arnebia euchroma and Lithospermum erythrorhizon; substantially lower concentrations than hepatotoxic PA-containing plants such as Symphytum (comfrey); primary safety consideration for internal use
β-sitosterol and stigmasterol (phytosterols) — anti-inflammatory contribution
Rosmarinic acid and caffeic acid derivatives — antioxidant, anti-inflammatory polyphenols

Anti-inflammatory: shikonin inhibits NF-κB nuclear translocation, suppresses COX-2 and PGE2 production, and reduces TNF-α and IL-6 in macrophage models; validates classical Heat-clearing and Toxicity-resolving actions in skin inflammation and burns
Anticancer: shikonin induces apoptosis via the mitochondrial pathway (caspase-3 activation, PARP cleavage) and inhibits topoisomerase II; demonstrated cytotoxicity against multiple cancer cell lines (hepatoma, breast, lung, colon); shikonin-based topical preparations are approved in China for certain skin tumors
Wound healing and burns: topical Zi Cao preparations (shikonin in oil base) accelerate wound re-epithelialization, reduce scar formation, and inhibit bacterial colonization in burn wounds; multiple Chinese clinical trials validate the traditional burn-treatment indication
Antiviral: shikonin demonstrates inhibitory activity against influenza A, HSV-1, and enterovirus; inhibits viral replication at multiple stages
Pyrrolizidine alkaloid safety: PA content in properly prepared Arnebia/Lithospermum root is substantially lower than in Symphytum species; hepatotoxicity risk is considered low at standard doses (3–9 g) in short-term use, but long-term high-dose internal use warrants liver enzyme monitoring

Pregnancy — cold nature, Blood-cooling action, and pyrrolizidine alkaloid exposure; avoid internal use in all trimesters
Spleen-Stomach Cold Deficiency — cold nature injures digestive Yang; caution in patients with chronic diarrhea, weak digestion, or Cold-pattern disorders
Internal use at high doses or long-term — pyrrolizidine alkaloid content, although low, warrants caution; standard doses (3–9 g) for short courses are considered safe; do not exceed 2–3 week continuous internal use without monitoring

Pyrrolizidine alkaloids: Arnebia euchroma and Lithospermum erythrorhizon contain low-level PAs; do not use internally above 9 g/day or for extended periods; topical use has no PA-related restriction
Two official source plants: Radix Arnebiae (Ruan Zi Cao 软紫草, from Arnebia euchroma) and Radix Lithospermi (Ying Zi Cao 硬紫草, from Lithospermum erythrorhizon) — both are Pharmacopoeia-approved; Arnebia euchroma is the primary modern source and has higher shikonin content
Staining: shikonin imparts an intense red-purple color to formulations and skin; inform patients that topical preparations will temporarily stain skin and clothing purple-red
Cold-pattern skin conditions: for sores or rashes without Heat (Cold-type skin disorders), Zi Cao may worsen the condition; confirm Heat pattern before prescribing

Anticoagulants (warfarin, heparin): theoretical additive antiplatelet effect via COX-2 inhibition and reduced platelet aggregation; monitor INR if combined with anticoagulant therapy