Traditionally used for
- Digestion
- Bowel health
- Menstrual & women's health
- Skin
Cautions & contraindications
- Heart conditions
- Toxic — professional use only
☯ TCM Properties
Clears Heat, eliminates Dampness, relieves pain, kills parasites
Traditional Chinese Uses
Ku Dou Zi is the seed (and sometimes herb) of Sophora alopecuroides, a legume of arid northwestern China. Intensely bitter and cold, it clears Heat, dries Dampness, relieves pain and kills parasites. It is used for Damp-Heat dysentery and diarrhea, damp sores, eczema and stubborn tinea, vaginal discharge (leucorrhea) and genital itch, and epigastric pain with acid regurgitation; it also has folk use in chronic prostatitis and cervical erosion.
The seeds are rich in quinolizidine alkaloids (matrine, oxymatrine, aloperine, sophocarpine, cytisine) which carry recognized toxicity affecting the nervous, respiratory and circulatory systems in overdose. It is therefore used in restrained doses and avoided in Spleen-Stomach cold-deficiency.
Western Herbalism Properties
Relationships
Full-screen graph →Click a node for details · double-click to expand it · Ctrl/⌘ + scroll or two fingers to zoom and pan.
Botanical Description
Ku Dou Zi is the seed of Sophora alopecuroides L. (Fabaceae), a perennial herb or subshrub 30–100 cm tall of arid steppe, gravelly slopes, and saline-alkaline soils across northwestern China (Xinjiang, Gansu, Ningxia, Inner Mongolia) and Central Asia. Stems are erect, branched, and finely silvery-pubescent. Leaves are odd-pinnate with 15–25 elliptic-oblong leaflets each 1.5–3 cm long. Terminal racemes bear dense, pale yellow to cream pea-like flowers in early summer. The legume is moniliform (constricted between seeds), 5–9 cm long, indehiscent, containing 3–7 oval, smooth, yellow-brown to dark brown seeds 5–7 mm long. Seeds contain quinolizidine alkaloids (matrine, oxymatrine, sophoridine, aloperine) and are TOXIC; small medicinal doses are used in TCM to clear heat-toxin, dry damp, and treat dysentery and parasitic infections. Overdose causes neuromuscular and cardiac toxicity; use only under qualified supervision.
Active Constituents
Aloperine
Lupin-type quinolizidine alkaloidA quinolizidine alkaloid first isolated from the seeds and leaves of Sophora alopecuroides, and the alkaloid most characteristic of this species rather than of Sophora flavescens. Preclinical work reports anti-inflammatory, antiviral and antitumour activity, but all of it is in vitro or in rodents; there is no human efficacy evidence.
Matrine
Quinolizidine (matrine-type) alkaloidShared with Sophora flavescens, so the two drugs overlap pharmacologically and toxicologically even though they are different species. Matrine is a CNS depressant at higher exposures and is the alkaloid most closely tied to the cardiac and neurological effects seen in Sophora alkaloid overdose.
Oxymatrine
Quinolizidine alkaloid N-oxideThe N-oxide of matrine and largely a prodrug for it, being reduced to matrine after oral dosing. Present in both Sophora alopecuroides and Sophora flavescens; almost all clinical work on oxymatrine used isolated oxymatrine of Sophora flavescens origin, not a Sophora alopecuroides preparation.
Sophocarpine
Quinolizidine (matrine-type) alkaloidAn unsaturated matrine analogue abundant in the seeds. It is one of the alkaloids quantified as a toxicity marker in Sophora alopecuroides seed extracts, and in zebrafish embryos it produced neurobehavioural changes at concentrations below those causing death or malformation.
Oxysophocarpine
Quinolizidine alkaloid N-oxideOne of the most abundant alkaloids reported in the aerial parts and seeds of this species, and one of the five markers used to compare the toxicity of differently processed seed material.
Sophoridine
Quinolizidine (matrine-type) alkaloidA matrine stereoisomer. Its reported intraperitoneal LD50 in mice is far lower than the intragastric LD50 of the total alkaloid fraction, which is why injectable sophoridine preparations carry very different risk from an oral decoction.
Cytisine
Bicyclic quinolizidine (cytisine-type) alkaloidReported among the quinolizidine alkaloids of Sophora alopecuroides seed. Cytisine is a potent partial agonist at nicotinic acetylcholine receptors and is the alkaloid responsible for the nausea, vomiting, tachycardia and, in severe poisoning, seizures seen with other cytisine-bearing legumes. Its presence is a specific reason not to treat this seed drug as interchangeable with Ku Shen root.
⚠ Drug Interactions
Nicotinic agents and smoking-cessation drugs (cytisinicline, varenicline)
Cytisine is reported among the seed alkaloids of Sophora alopecuroides, and cytisine is a high-affinity partial agonist at alpha4beta2 nicotinic acetylcholine receptors, the same target as varenicline and as cytisinicline itself. No human interaction study exists; the concern is pharmacological overlap plus the documented clinical picture of Sophora alkaloid overdose, which includes palpitation, pallor, vomiting and spasm.
Clinical note: Do not combine Ku Dou Zi with nicotinic smoking-cessation drugs or heavy nicotine use, and treat unexplained nausea, vomiting and tachycardia in a patient taking this herb as possible alkaloid toxicity.
Antiarrhythmics and other negative chronotropic or hypotensive drugs (beta-blockers, verapamil, diltiazem)
The total alkaloid fraction of Sophora alopecuroides depresses the circulatory, respiratory and nervous systems of mice and rabbits, and human Sophora alkaloid poisoning presents with palpitation, pallor, falling blood pressure and dyspnoea. The published human poisoning series is dominated by Sophora flavescens overdose rather than Sophora alopecuroides, so the cardiovascular signal is extrapolated across the shared matrine-type alkaloids rather than measured for this species.
Clinical note: Avoid in patients on rate-limiting cardiac drugs or with conduction disease; if used at all, keep to conventional doses of a properly processed drug and monitor pulse and blood pressure.
CNS depressants (benzodiazepines, opioids, sedating antihistamines)
Matrine-type alkaloids are sedative and the total alkaloids of this species depress respiration in animals; excessive use in humans is reported to cause dizziness, headache, chest tightness and dyspnoea. The evidence is animal toxicology plus clinical poisoning description, not a controlled interaction study.
Clinical note: Counsel against combining with sedatives or alcohol, and warn about driving.
CYP2B6 and CYP3A4 substrates (e.g. efavirenz, bupropion, midazolam, ciclosporin)
Matrine and oxymatrine dose-dependently induced CYP2B1 activity and expression in rats, and whole Sophora flavescens extract induced CYP3A and P-glycoprotein. Those experiments used isolated matrine and oxymatrine or Sophora flavescens root, not Sophora alopecuroides; because this species contains the same alkaloids the induction risk is plausible but unmeasured for the seed drug.
Clinical note: Treat as an unquantified induction risk with narrow-therapeutic-index drugs; prefer to avoid concurrent use rather than attempt dose adjustment.
Sophora flavescens (Ku Shen) and Sophora tonkinensis (Shan Dou Gen)
Ku Dou Zi seed, Ku Shen root and Shan Dou Gen root all carry matrine, oxymatrine, sophocarpine and sophoridine. Prescribing more than one in the same formula stacks the same toxic alkaloid load while appearing on the prescription as separate herbs. Acute Sophora alkaloid poisoning in Chinese medicine practice is usually attributed to excessive dose, and it presents with dizziness, vomiting and palpitation.
Clinical note: Count the total matrine-type alkaloid burden across the whole formula rather than checking each herb's dose in isolation, and do not combine Sophora species without a clear reason.
Evidence Tier
Limited evidence · 2 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
1
0 verified · 1 unverified
Show the study
In vitro / animal
1
0 verified · 1 unverified
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
Different processing methods change the oral toxicity induced by Sophora alopecuroides seeds and the contents of five main toxic alkaloids from the ethanol extracts determined by a validated UHPLC-MS/MS assay
Rodent oral toxicity of Sophora alopecuroides seed ethanol extracts was compared across processing methods alongside quantification of five principal toxic alkaloids by a validated UHPLC-MS/MS assay. The work supports the traditional insistence that this seed be processed before use: processing altered both the measured alkaloid content and the observed oral toxicity. It is an animal and analytical study in this species specifically, not a human trial.
Acute Sophora alkaloid poisoning in Hong Kong
A review of clinically confirmed acute Sophora alkaloid poisonings, in which the cases were most often attributed to excessive doses of Sophora flavescens rather than of Sophora alopecuroides, and the presentation was dominated by dizziness, vomiting and palpitation. Included here because it is the best human evidence for what matrine-type alkaloid overdose looks like; readers should note it does not establish a poisoning frequency for Sophora alopecuroides itself.
⚠ Safety & Contraindications
- Heart conditions
- Toxic — professional use only
Contraindications
The dosage for oral use should be not large since it is poisonous. And its use is cautious in patients with deficiency-cold of the spleen and stomach.
Source: Xi S, Gong Y. Essentials of Chinese Materia Medica and Medical Formulas. Academic Press/Elsevier, 2017, pp. 46–50.
Historical Texts
Xinjiang Zhong Cao Yao Shou Ce (Handbook of Xinjiang Chinese Herbal Medicine)
Modern, 1970References
- Ruizhou Wang, Xinxin Deng, Qixia Gao, Xiuli Wu, Lu Han, Xiaojuan Gao, Shipeng Zhao, Weibin Chen, Rongrong Zhou, Zhiyong Li, Changcai Bai. Sophora alopecuroides L.: An ethnopharmacological, phytochemical, and pharmacological review . Journal of Ethnopharmacology (2020) [DOI]
- Longtai You, Chunjing Yang, Yuanyuan Du, Wenping Wang, Mingyi Sun, Jing Liu, Baorui Ma, Linnuo Pang, Yawen Zeng, Zhiqin Zhang, Xiaoxv Dong, Xingbin Yin, Jian Ni. A Systematic Review of the Pharmacology, Toxicology and Pharmacokinetics of Matrine . Frontiers in Pharmacology (2020) [DOI]
- Xia Li, Ziwei Tang, Li Wen, Cen Jiang, Quansheng Feng. Matrine: A review of its pharmacology, pharmacokinetics, toxicity, clinical application and preparation researches . Journal of Ethnopharmacology (2021) [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.
📝 Notes
Public notes from the community and your own private notes on Ku Dou Zi.
No notes yet.