Bai Wei
StarCynanchum atratum Bunge
Traditionally used for
- Colds & fever
- Digestion
- Urinary & fluids
- Skin
Cautions & contraindications
- Pregnancy
- Heart conditions
☯ TCM Properties
Clears Deficiency Heat; Clears Heat and Cools the Blood; Promotes Urination and Relieves Stranguria; Resolves Toxicity and Heals Sores
Traditional Chinese Uses
Bai Wei (白薇) is the root and rhizome of Cynanchum atratum Bunge (Apocynaceae), Radix Cynanchi Atrati. It is bitter and salty and cold, entering the Stomach, Liver and Kidney channels. It clears deficiency Heat, clears Heat and cools the Blood, promotes urination to relieve stranguria, and resolves toxicity to heal sores.
It is used for the lingering, low-grade fever that follows a febrile illness once Yin has been damaged, for steaming-bone fever and night sweats, and for the afternoon fevers of consumptive disorders. Distinctively, it is safe and appropriate in postpartum fever and in fever during pregnancy, where stronger cold herbs are avoided. Its cooling of the Blood while promoting urination suits hot painful urinary dribbling with blood, and it is applied to hot sores, swellings and snake bite.
It is cold and is used cautiously in Spleen and Stomach deficiency Cold with loose stools and poor appetite.
Western Herbalism Properties
Relationships
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Botanical Description
Cynanchum atratum (Bai Wei, swallowwort) is a perennial herb in the Apocynaceae family (formerly Asclepiadaceae), growing 30 to 70 centimeters tall from a short rhizome bearing a dense fascicle of slender, pale yellowish-brown to dark brown radial roots that are the medicinal material. The erect, simple, finely pubescent stems bear opposite, ovate to broadly elliptic leaves 6 to 12 centimeters long, with entire margins, acute tips, and softly hairy surfaces. From late spring to summer, dense axillary cymes of small dark purple-black, almost blackish, star-shaped flowers about 1 centimeter across are produced; the corolla has five spreading lobes, and a characteristic dark corona sits at the center. The fruits are slender, spindle-shaped follicles 5 to 7 centimeters long, splitting along one side to release flat seeds tipped with silky white coma. Native to East Asia, including China, Korea, Japan, and the Russian Far East, growing in grasslands and open woodland. Roots are harvested in spring or autumn.
Active Constituents
Cynatratoside A
C21 steroidal (pregnane) glycosideOne of the principal C21 steroidal glycosides of the root and a designated chemical marker for the drug. Given orally at 10 and 40 mg/kg it reduced concanavalin A-induced immune-mediated liver injury in mice, which is consistent with the immunosuppressive profile of this compound class.
Cynanversicoside A
C21 steroidal (pregnane) glycosideUsed as a quality marker for Baiwei drug material. Note that the cynanversicosides were first described from Cynanchum versicolor, the other species sold under this pinyin name, so their presence is not by itself proof of C. atratum identity.
Atratcynosides A-F
C21 steroidal (pregnane) glycosidesA series of glycosides isolated specifically from C. atratum root, several of which were immunosuppressive in vitro with IC50 values between 3.3 and 7.0 micromolar. They carry the 14,15-seco-pregnane and 13,14:14,15-diseco-pregnane skeletons characteristic of this species.
4-Hydroxyacetophenone (p-hydroxyacetophenone)
AcetophenoneA simple phenolic ketone used as a marker constituent of Baiwei. The acetophenones are the non-glycosidic part of the profile and are among the compounds most often quantified for quality control.
2,4-Dihydroxyacetophenone
AcetophenoneA companion acetophenone marker of the root, quantified alongside 4-hydroxyacetophenone in pharmacopoeial-style assays.
Sinapic acid
Hydroxycinnamic (phenolic) acidA phenolic constituent of Cynanchi Atrati Radix identified as acting on the regulator of calcineurin 1 (RCAN1) pathway to damp skin inflammation, giving a molecular handle on the herb's traditional use for heat rashes and sores.
⚠ Drug Interactions
Cynanchum versicolor Bunge root (sold interchangeably as Bai Wei)
Chinese practice accepts both C. atratum and C. versicolor as the source of Baiwei, and the two are routinely interchanged in commerce. A 2025 review in Journal of Integrative Medicine that examined them together reports significant disparities in their chemical composition and pharmacological effects, so results obtained on one species cannot be assumed to hold for the other. Much of the older Baiwei literature does not state which species was used.
Clinical note: When the intended action depends on a specific published finding, require the supplier to state the binomial. Treat Baiwei studies that name only the pinyin as species-indeterminate.
Immunosuppressants (e.g. ciclosporin, tacrolimus, azathioprine, corticosteroids)
C21 steroidal glycosides isolated from C. atratum root suppressed lymphocyte proliferation in vitro with IC50 values of 3.3 to 7.0 micromolar, and cynatratoside A blunted concanavalin A-driven immune hepatitis in mice. Whether these concentrations are reached systemically from a decoction has not been established, so the additive risk is inferred from pharmacology rather than observed.
Clinical note: No documented human cases. Exercise ordinary caution in transplant recipients and others on immunosuppression, and do not use the herb as a substitute for monitoring.
Digoxin and other Na+/K+-ATPase-dependent drugs
Na+/K+-ATPase inhibitory activity is listed among the reported pharmacological actions of C. atratum. Its C21 steroidal glycosides are pregnane glycosides, structurally distinct from the cardenolides of Digitalis, and no cardiotoxicity or digoxin interaction has been reported clinically, so this is a mechanism-level caution only and should not be presented to patients as a cardiac-glycoside risk.
Clinical note: No monitoring change is warranted on current evidence. Note it only if a patient on digoxin develops unexplained symptoms while taking the herb.
Dosage
| Form | Amount | Frequency | Duration | Population | Notes |
|---|---|---|---|---|---|
| decoction | 5–10 g | Daily | — | — | 中国药典 2020 【用法与用量】5～10g。 【性味与归经】苦、咸，寒。归胃、肝、肾经。 — Chinese Pharmacopoeia 2020, quoted verbatim; route and cautions preserved. Replaces a cleared category-filler value. |
Evidence Tier
Moderate evidence · 3 studiesRecorded studies by study design, strongest design at the top. This is a study-design tier only, not a GRADE rating: it does not weigh risk of bias, consistency or precision.
Systematic review / meta-analysis
0
Randomized controlled trial
0
Other clinical trial
0
Observational / case report
0
In vitro / animal
3
1 verified · 2 unverified
Show 3 studies
- A C21-Steroidal Glycoside from Cynanchum atratum Attenuates Concanavalin A-Induced Liver Injury in Mice
- Immunosuppressive C21 steroidal glycosides from the root of Cynanchum atratum
- Cynanchi atrati and Its Phenolic Constituent Sinapic Acid Target Regulator of Calcineurin 1 (RCAN1) to Control Skin Inflammation
Other / unclassified
0
Verified: design read from PubMed for a DOI that resolves to the cited paper Unverified: taken from the study's recorded description
Clinical Studies
A C21-Steroidal Glycoside from Cynanchum atratum Attenuates Concanavalin A-Induced Liver Injury in Mice
Cynatratoside A given orally at 10 and 40 mg/kg reduced concanavalin A-induced immune-mediated hepatitis in mice, lowering transaminases and hepatic inflammatory signalling. Evidence that a defined C21 glycoside of this species, not just the crude extract, carries immunomodulatory activity.
Immunosuppressive C21 steroidal glycosides from the root of Cynanchum atratum
Six new C21 steroidal glycosides (atratcynosides A-F) and a dideoxysaccharide were isolated from C. atratum root. Several showed dose-dependent immunosuppressive activity with IC50 values of 3.3 to 7.0 micromolar, identifying the glycoside fraction as the immunoactive part of the drug.
Cynanchi atrati and Its Phenolic Constituent Sinapic Acid Target Regulator of Calcineurin 1 (RCAN1) to Control Skin Inflammation
Cynanchi Atrati Radix extract and its constituent sinapic acid suppressed skin inflammation through the regulator of calcineurin 1 (RCAN1) pathway. Provides a defined molecular target for the herb's traditional application to heat sores and rashes.
Historical Texts
Shen Nong Ben Cao Jing
Han dynastyBen Cao Gang Mu
Ming dynastyReferences
- Yaqian Zhang, Yuqiao Yang, Chaozhuo Yan, Jin Li, Peng Zhang, Rui Liu, Jun He, Yan-xu Chang. A review of the ethnopharmacology, phytochemistry and pharmacology of Cynanchum atratum . Journal of Ethnopharmacology (2022) [DOI]
- Wei Xie, Xin-yang Liu, Xia Li, Yong-sheng Jin. Cynanchum atratum Bunge and Cynanchum versicolor Bunge for Baiwei: An updated review of their botany, phytochemistry, traditional uses and pharmacological activities . Journal of Integrative Medicine (2025) [DOI]
- Hong Bai, Wei Li, Yoshihisa Asada, Tadaaki Satou, Yuanshu Wang, Kazuo Koike. Twelve pregnane glycosides from Cynanchum atratum . Steroids (2009) [DOI]
This information is for educational purposes only and is not intended to replace professional medical advice. Always consult a qualified healthcare provider before using any herbal remedy, especially if you are pregnant, nursing, or taking medications.
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