Arnebia Root / Gromwell Root — Safety & Interactions
Zi Cao · Radix Arnebiae Seu Lithospermi
Use with caution. Practitioner review recommended before use.
Contraindications
- 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
Cautions
- 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
Drug Interactions
| Drug Class / Substrate | Mechanism | Severity | Source |
|---|---|---|---|
| Anticoagulants (warfarin, heparin): theoretical additive antiplatelet effect via COX-2 inhibition and reduced platelet aggregation; monitor INR if combined with anticoagulant therapy | |||
Pregnancy
Not recommended during pregnancy. Consult a qualified practitioner before any use.
This information is for educational purposes only and does not constitute medical advice. Always consult a qualified healthcare provider before using herbal medicines, especially if you take prescription medications.