Shan Dou Gen
StarSophora tonkinensis Gagnep.
Traditionally used for
- Nose & throat
- Cough & breathing
- Digestion
Cautions & contraindications
- Pregnancy
- Liver conditions
- Seizure disorders
- Toxic — professional use only
☯ TCM Properties
Clears Heat and Resolves Toxicity; Benefits the Throat and Reduces Swelling; Clears Lung Heat; Clears Stomach Heat
Traditional Chinese Uses
Shan Dou Gen (sophora root) is a bitter, cold, toxic herb with powerful Heat-toxin-clearing properties in the throat and upper respiratory tract. It is among the most effective herbs for severe sore throat, tonsillar swelling, and pharyngitis from Heat toxin accumulation. Its cold, bitter nature must be used in controlled doses and for short durations, as overdose can cause vomiting and neurological side effects. It is often used topically as a gargle or in small doses internally for acute throat conditions.
Pharmacological Effects
- Antiinfectious: Strongly active against tubercle bacilli; inhibited Staphylococcus aureus, Epidermophyton floccosum and Candida albicans; stimulated the reticuloendothelial system and raised macrophage numbers.
- Antineoplastic: i.p. aqueous extract (500 mg/kg) cured over 60% of rats bearing Yoshida sarcoma or hepatomas; matrine (2.5 mg/kg) inhibited Ehrlich ascites carcinoma and S180 in vitro and in vivo; oxymatrine active against S180 at 1.25 mg/kg with chemotherapeutic index 7.8x mitomycin C.
- Leukocytotic: Total alkaloids and oxymatrine raised WBC in normal rabbits; matrine or oxymatrine i.m. for 10 days sped WBC recovery in X-ray-induced leukopenia in rabbits.
- Antiarrhythmic: Total alkaloids, matrine and oxymatrine antagonized arrhythmias induced by aconitine, digitoxin, chloroform-epinephrine or KCl ('broad-spectrum'); in cats, reversal of cedilanid arrhythmia required an intact spinal cord, implicating the CNS.
- Antiasthmatic: Oral total alkaloids or oxymatrine protected guinea pigs from histamine asthma; oxymatrine i.m. inhibited PCA and ACA and suppressed serum IgE formation in rabbits/rats.
- Antiulcerative: Sophoradochromene i.m. prevented experimental gastric ulcer in rats; precipitates from the ethanolic extract healed pylorus-ligation, stress and acetic-acid ulcers.
Source: Zhu YP. Chinese Materia Medica: Chemistry, Pharmacology and Applications. Harwood Academic, 1998, p. 202.
Relationships
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Botanical Description
Sophora tonkinensis is a small evergreen shrub of the family Fabaceae, native to limestone hills and rocky slopes in southwestern China and northern Vietnam. The plant grows to roughly 1 to 2 meters tall, with finely pubescent young branches and pinnately compound leaves bearing 11 to 19 small elliptic to ovate leaflets that are gray-green and softly hairy beneath. Loose terminal racemes of pale yellow pea-like flowers appear in summer, followed by constricted, beaded legumes containing several seeds. The medicinal portion is the long, cylindrical, branched taproot and rhizome, harvested in autumn, woody and bitter, with a yellow-brown bark and pale yellow interior rich in quinolizidine alkaloids including matrine and oxymatrine. These alkaloids are responsible for both its therapeutic activity and its narrow safety margin.
Active Constituents
Matrine
Quinolizidine (matrine-type) alkaloidConcentration: the Chinese Pharmacopoeia sets matrine plus oxymatrine combined at not less than 0.6% of the dried root and rhizome
A principal marker and a principal toxin. Matrine has anti-inflammatory, antiviral and antitumour activity in preclinical models, but it is also the constituent that carries the herb's narrow margin of safety: it first excites and then paralyses the central nervous system, producing dizziness, blurred vision, weakness and somnolence at low toxic exposure and seizure-like convulsions and respiratory paralysis at higher exposure.
Oxymatrine
Quinolizidine (matrine-type) alkaloid N-oxideConcentration: counted with matrine toward the pharmacopoeial minimum of 0.6% combined
The N-oxide of matrine and usually the more abundant of the pair. It is reduced to matrine in vivo, and animal work attributes the herb's hepatotoxicity to oxymatrine together with its metabolite matrine rather than to either alone.
Sophoridine
Quinolizidine alkaloidA matrine stereoisomer reported to cause hepatotoxicity, neurotoxicity and cytotoxicity in in vitro and animal studies, adding to the total alkaloid toxic burden of the drug.
Sophocarpine
Quinolizidine alkaloidAn unsaturated matrine-type alkaloid of the rhizome with antiviral and anti-inflammatory activity in preclinical assays.
Cytisine
Cytisine-type quinolizidine alkaloidA partial agonist at nicotinic acetylcholine receptors. Cytisine is toxic in its own right, and its presence in the root is a distinct pharmacological hazard from the matrine-type alkaloids, contributing to nausea, vomiting and autonomic symptoms in poisoning.
Trifolirhizin
Pterocarpan glycosideOne of the five major active flavonoids of the root, with anti-inflammatory and antitumour activity reported in vitro. Its aglycone maackiain is also present.
Maackiain
PterocarpanA pterocarpan phytoalexin of the root, antifungal and antimicrobial, and part of the flavonoid fraction that carries much of the herb's antimicrobial activity against throat pathogens.
Sophoranone
Prenylated flavanoneA prenylated flavanone characteristic of S. tonkinensis, cytotoxic in tumour cell lines and one of the major active flavonoids quantified in the root.
⚠ Drug Interactions
Hepatotoxic drugs (paracetamol/acetaminophen, methotrexate, isoniazid, valproate)
Animal and metabolomic work identifies the liver as the primary target organ of S. tonkinensis, with a clear dose-time-toxicity relationship, and attributes the injury to oxymatrine and its metabolite matrine. Integrated omics studies in mice and rats implicate disturbed bile acid, lipid and amino acid metabolism and oxidative stress. Because the herb's therapeutic and toxic doses are close together, any second hepatotoxin materially shortens the margin.
Clinical note: Do not combine with hepatotoxic drugs. Keep to the pharmacopoeial dose of 3-6 g, never extend courses beyond a few days, and check liver enzymes if use exceeds one week or if the patient is on any drug with hepatic risk.
Antiepileptic drugs (e.g. valproate, levetiracetam, carbamazepine)
Matrine-type alkaloids first excite and then depress the central nervous system, and excessive central excitation can produce epileptiform convulsions. Toxic encephalopathy following radix Sophorae tonkinensis has been reported in the neurological literature, and a Hong Kong poison-centre series documents acute Sophora alkaloid poisoning. Adding a herb that lowers the seizure threshold to an epilepsy regimen is a direct clinical hazard rather than a pharmacokinetic subtlety.
Clinical note: Avoid in patients with epilepsy or any history of seizures. Any patient developing dizziness, tremor, blurred vision or twitching on this herb should stop it immediately and be assessed.
Central nervous system depressants (opioids, benzodiazepines, sedating antihistamines)
Matrine's central action is biphasic: initial excitation followed by paralysis. Clinical poisoning reports describe drowsiness, weakness and, at severe exposure, respiratory paralysis that can be fatal. Adding a respiratory depressant to a herb whose fatal mechanism is respiratory paralysis is an obvious compounding risk, although no formal interaction study exists.
Clinical note: Avoid in patients on opioids or sedatives, particularly the elderly and those with respiratory disease.
Nicotinic agents (varenicline, cytisinicline, nicotine replacement)
The root contains cytisine, a nicotinic acetylcholine receptor partial agonist and the parent compound of licensed smoking-cessation drugs. The quantity delivered by a therapeutic decoction has not been measured against therapeutic cytisine doses, so this is an extrapolation from constituent identity.
Clinical note: Note in patients using smoking-cessation pharmacotherapy; not a reason to withhold treatment on its own.
CYP2D6 and CYP3A4 substrates
Rodent cocktail-probe work has suggested oxymatrine may induce CYP2D6 and CYP3A4, but the available report is a preprint and there is no human pharmacokinetic study of Shan Dou Gen against CYP probes. This is recorded only so it is not mistaken for a known safe combination.
Clinical note: Insufficient evidence to act on. Given the herb's short courses and narrow safety margin, toxicity monitoring matters more than CYP considerations.
Dosage
| Form | Amount | Frequency | Duration | Population | Notes |
|---|---|---|---|---|---|
| decoction | 3–6 g | Daily | — | — | 中国药典 2020 【用法与用量】3～6g。 【性味与归经】苦，寒；有毒。归肺、胃经。 — Chinese Pharmacopoeia 2020, quoted verbatim; route and cautions preserved. Replaces a cleared category-filler value. |
Evidence Tier
Moderate evidence · 4 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
3
0 verified · 3 unverified
Show 3 studies
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
Acute Sophora alkaloid poisoning in Hong Kong
Retrospective review of human poisoning cases involving Sophora alkaloids reported to the Hong Kong poison information service, documenting the clinical syndrome of acute matrine-type alkaloid toxicity. Direct human evidence that this herb causes acute poisoning in ordinary clinical use.
Metabolomics- and systems toxicology-based hepatotoxicity mechanism of Sophorae Tonkinensis Radix et Rhizoma in rats
Combined metabolomics and systems toxicology in rats to map the hepatotoxic mechanism of the whole drug, identifying disturbed metabolic pathways underlying the liver injury seen with S. tonkinensis.
Toxicity comparison of different active fractions extracted from radix Sophorae tonkinensis in zebrafish
Compared the toxicity of separated fractions of the root in zebrafish, attributing the bulk of the observed toxicity to the alkaloid fraction rather than the flavonoid or polysaccharide fractions.
Antiviral Matrine-Type Alkaloids from the Rhizomes of Sophora tonkinensis
Isolated matrine-type alkaloids from the rhizome and characterised their antiviral activity in cell-based assays, providing chemical support for the traditional use in throat and lung heat-toxin patterns.
⚠ Safety & Contraindications
- Pregnancy
- Liver conditions
- Seizure disorders
- Toxic — professional use only
Contraindications
Contraindicated in pregnancy and in the weak or depleted with cold in the middle burner.
Side Effects
- Nausea, vomiting, dizziness and headache are common
- Severe cases: sweating, palpitation, dyspnea and convulsion
Source: Zhu YP. Chinese Materia Medica: Chemistry, Pharmacology and Applications. Harwood Academic, 1998, p. 202.
Safety Warnings
- The therapeutic margin is narrow; poisonings follow modest overdose.
- Not for prolonged use.
⚠ Toxicity Information
Nausea, vomiting, dizziness and — in overdose — ataxia, muscle tremor, respiratory depression and convulsion. Poisonings from exceeding the dose are well reported.
Historical Texts
Kai Bao Ben Cao
Song dynasty, 973-974Chinese Pharmacopoeia (Zhonghua Renmin Gongheguo Yaodian)
Modern, 2020 editionReferences
- Zeng FF, Chen ZH, Luo FH, Liu CJ, Yang X, Zhang FX, Shi W. Sophorae tonkinensis radix et rhizoma: A comprehensive review of the ethnopharmacology, phytochemistry, pharmacology, pharmacokinetics, toxicology and detoxification strategy . Journal of Ethnopharmacology (2025) [DOI]
- You L, Yang C, Du Y, Wang W, Sun M, Liu J, Ma B, Pang L, Zeng Y, Zhang Z, Dong X, Yin X, Ni J. A Systematic Review of the Pharmacology, Toxicology and Pharmacokinetics of Matrine . Frontiers in Pharmacology (2020) [DOI]
- Li XL, Zhao HT, Han J, Yan ZR, Wang HY. Toxic encephalopathy induced by radix Sophorae tonkinensis . Acta Neurologica Belgica (2021) [DOI]
- Zhang SN, Li HM, Li XZ, Yang WD, Zhou Y. Integrated omics and bioinformatics analyses for the toxic mechanism and material basis of Sophorae Tonkinensis radix et rhizome-induced hepatotoxicity . Journal of Pharmaceutical and Biomedical Analysis (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.
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