Zi Cao (紫草) — Gromwell Root: TCM Uses, Burns Treatment & Formulas

At a Glance

Herb: Zi Cao
Chinese name: 紫草 (Zǐ Cǎo)
Latin name: Lithospermum erythrorhizon Sieb. et Zucc.
Nature: Cold
Taste: Sweet / Salty
Meridian: Heart / Liver
Category: Herbs that Cool Blood
Introduction: Zi Cao (紫草), the dried root of Arnebia euchroma (Royle) Johnst. or Lithospermum erythrorhizon Sieb. et Zucc., is distinguished by its striking purple-red color from shikonin and alkannin pigments, which are also responsible for its primary pharmacological activities. Recorded in the Shen Nong Ben Cao Jing, it is used both internally for blood-heat rashes and febrile diseases, and topically for burns, sores, and skin infections. Modern pharmacology has confirmed that shikonin and its derivatives exhibit antibacterial, antiviral, anti-inflammatory, wound-healing, and notable antitumor activities across multiple cancer cell lines.

Clears heat and cools blood — treats blood-level heat with hemorrhagic rashes and purpura
Activates blood and resolves toxicity — treats carbuncles, boils, and skin infections
Vents rashes — promotes the complete expression of measles and exanthematous fevers
Heals wounds and regenerates tissue — topical application for burns, sores, and frostbite

Standard dose: 3–10 g internally
Contraindicated in loose stools or diarrhea — its slippery nature worsens loose stool
Use with caution in spleen-stomach deficiency
The purple pigment (shikonin) will stain urine reddish — warn patients this is harmless
Topical preparations are safe for external use; large internal doses rarely needed

Zi Cao Hua Ban Tang (紫草化斑汤): Zi Cao, Sheng Di, Chi Shao, Mu Dan Pi, Huang Lian — cools blood and resolves toxin for measles rash and purpura
Zi Cao Gao (紫草膏): Zi Cao in sesame oil or beeswax base — classic topical preparation for burns, eczema, and chronic skin ulcers; widely used in Chinese dermatology
Combined with Jin Yin Hua, Lian Qiao, Da Qing Ye for severe febrile rash

For measles with incomplete eruption and purplish rash: combine with Chan Tui, Niu Bang Zi, Lian Qiao (Zi Cao Kuai Ban Tang).
For blood heat skin rashes and urticaria: combine with Chi Shao, Mu Dan Pi, Sheng Di Huang.
For burns and wounds (topical): Zi Cao in sesame oil — foundational ingredient of Zi Cao You (紫草油).
For eczema and dermatitis (topical): combine with Huang Bai, Bai Xian Pi, Di Fu Zi in oil base.
For cervical erosion (topical suppository): Zi Cao with Huang Lian, Bing Pian.
For constipation from intestinal dryness: use alone or with Huo Ma Ren.
For antiviral rashes (chickenpox, shingles): combine with Ban Lan Gen, Lian Qiao.

shikonin
- Antitumor: inhibits tumor cell proliferation via ROS generation and mitochondrial apoptosis pathway — active against colon, lung, cervical cancer
- Antiparasitic: inhibits Leishmania and Plasmodium
Anti-inflammatory
- inhibits COX-2, NF-κB, and 5-LOX pathways
Antiviral
- active against herpes simplex, HIV, and influenza viruses
Antibacterial
- active against Staphylococcus and E. coli
naphthoquinones
- Contraceptive: inhibit implantation (traditional use in China)

Shen Nong Ben Cao Jing (《神农本草经》): ‘Governs Heart and abdominal pathogenic qi, five types of jaundice, supplements the center and benefits qi, facilitates the nine orifices, and unblocks the waterway.’
Ben Cao Gang Mu (《本草纲目》): ‘Treats spotted rashes, pox toxins, activates blood and cools blood, and facilitates the Large Intestine.’
Ben Cao Jing Shu (《本草经疏》): ‘Gromwell Root receives the harmonious qi of Earth and also draws on the yang qi of Heaven to grow; hence it is bitter in flavor and cold in qi, non-toxic; enters the blood aspect of the Pericardium and Liv er channels. Bitter can cool blood, cold can drain heat — hence it governs pathogenic heat qi in the Heart and abdomen.’
Ben Cao Zheng Yi (《本草正义》): ‘Gromwell Root is bitter and cold in flavor and qi; its purple color enters blood — hence it clears and purges heat in the blood aspect.’