Shan Dou Gen (Sophora Root or Subprostrate)

Chinese Herb Actions

Chinese Herb Dosage

• What is the dosage of Shan Dou Gen?

  Our record gives 3–9 g of the root and rhizome. The Chinese Pharmacopoeia specifies a narrower 3–6 g. Both figures are recorded here for reference only. This is one of the few herbs on this site where the difference between two published ranges is worth stating plainly, because the margin between the therapeutic dose and the toxic dose is genuinely narrow — the safety literature on this herb is largely a literature about dose.

  • Our record — 3–9 g; part used, root and rhizome.
  • Chinese Pharmacopoeia — a dose of 3–6 g per 60 kg body weight is the figure cited in the pharmacological literature when researchers convert human dosing to animal models.

  Discrepancy note: our recorded upper limit (9 g) exceeds the Chinese Pharmacopoeia upper limit (6 g). Both ranges are published; we report both rather than silently reconciling them, and our own record is left unchanged pending review. Given the documented dose-dependent toxicity of this herb, the difference is not academic.

  This is not dosing guidance. The figures above are catalogued as reference data. Shan Dou Gen is a herb whose published safety reviews explicitly conclude that it should be used only under a physician’s direction and strictly within pharmacopoeial limits, and warn against its casual use in folk or self-devised preparations for colds and sore throats.

  Source: our own herb record dosage and part used; Chinese Pharmacopoeia range as cited in PMID 36557783, PMC 9780913; supervision statement per PMID 29271144. Reference only — not a prescription and not dosing advice.

Chinese Herb Contraindications & Cautions

• Is Shan Dou Gen safe? What are the cautions?

  Shan Dou Gen is one of the Chinese herbs with a genuine, well-documented acute-poisoning record, and published safety reviews conclude it should be used only under a physician’s direction and strictly within pharmacopoeial dose limits. Our own record carries the traditional caution — not to be used in diarrhoea from Spleen deficiency — but the modern safety literature adds a great deal more, and it belongs on any honest page about this herb.

  • Our record’s traditional caution — contraindicated in diarrhoea arising from Spleen deficiency. Consistent with its bitter, cold nature.
  • Narrow margin between effect and harm — a 2017 systematic safety review of this herb concluded that its toxicity affects the nervous, digestive and respiratory systems, and specifically cautioned against casual use in folk remedies and self-devised recipes for colds and sore throat.
  • Children and adolescents — the same review states that high-dose and long-term use may cause serious brain damage, and singles out adolescents and children as being at particular risk.
  • Not a self-treatment herb — its most popular indication (a sore throat) is exactly the complaint people are most likely to self-treat. That mismatch is the practical reason this herb accounts for a share of herb-related poisoning reports in China.
  • Overlap with other matrine-containing herbs — Ku Shen and concentrated matrine or oxymatrine preparations draw on the same alkaloid class. Taking more than one without a practitioner’s knowledge stacks the same compounds.

  Framing: nothing above is usage guidance, and no monitoring or preparation advice is given or implied. These are the documented circumstances in which harm has been recorded. Shan Dou Gen is a prescription-level herb for a qualified practitioner, and anyone with a severe or persistent sore throat needs a diagnosis rather than a herb.

  Source: our own herb record caution entry; modern safety findings per PMID 29271144 (systematic safety evaluation and risk control), PMID 33622209 and PMID 39244176 (toxicology reviews). Reference information, not medical advice.

Chinese Herb Toxicity & Overdose

• Is Shan Dou Gen toxic?

  Yes — and unusually among the herbs on this site, the toxicity is acute, dose-dependent, documented in the clinical literature, and has been fatal. A 2017 systematic review of the Chinese toxicity record found that harm from this herb involves the nervous, digestive and respiratory systems, and that respiratory failure may be the direct cause of death in severe cases. This is documented as neutral reference fact: what has been recorded, and in what circumstances.

  • Reported symptom picture — the review lists headache, dizziness, vomiting, nausea, abdominal pain, weakness of the limbs, palpitations and chest oppression; and in severe cases pallor, trembling limbs, convulsions, chills, rapid heart rate, falling blood pressure, shock and respiratory failure leading to death.
  • Neurotoxicity — a case of toxic encephalopathy induced by radix Sophorae tonkinensis is published in the neurology literature. The same 2017 review reports that high-dose and long-term use may cause serious brain damage, particularly in adolescents and children.
  • The circumstance that recurs — excess dose. The reviews consistently frame the problem as overdose and unsupervised use rather than as an unpredictable idiosyncratic reaction. The therapeutic-to-toxic margin is genuinely narrow.
  • Which organs, in laboratory work — separate mechanistic studies describe hepatotoxicity (metabolomics and systems toxicology in rats) and pulmonary toxicity (integrated omics) from this herb. A 2025 comprehensive review summarises toxic effects on liver, nerves, heart and gastrointestinal tract, and states that the herb requires attenuation — by processing or by combination — before use.
  • The responsible compounds — the quinolizidine alkaloids, principally matrine and oxymatrine, which are also the pharmacopoeial quality markers for the herb. The compounds that make it work are the compounds that make it dangerous; they cannot be separated by intention.
  • Relationship to Ku Shen — Sophora flavescens contains the same alkaloid pair, and matrine hepatotoxicity is documented for that herb too. But Ku Shen does not carry a comparable acute-poisoning record, and the two should not be treated as interchangeable in either direction.

  What this section deliberately does not do: it gives no dose ceilings framed as instructions, no preparation or processing method, and no monitoring protocol. Those are clinical decisions. This is a reference record of documented harm.

  Sources: PMID 29271144 (safety evaluation and risk control; organ systems, symptom picture, respiratory failure as direct cause of death, risk in children and adolescents); PMID 33417151, DOI 10.1007/s13760-020-01587-w (toxic encephalopathy case, Acta Neurologica Belgica); PMID 39244176, DOI 10.1016/j.jep.2024.118784 (comprehensive review: toxicology and attenuation); PMID 33622209 (pharmacological and toxicological review); PMID 36467100, PMC 9717682 (hepatotoxicity mechanism); PMID 34333216 (pulmonary toxicity mechanism); PMID 33041782, PMC 7526649 (systematic review of matrine pharmacology, toxicology and pharmacokinetics); PMID 32717422 (matrine liver-cell toxicity). Neutral reference facts, not a safety guarantee and not usage guidance.

Herb-Drug Interactions

• Does Shan Dou Gen interact with medications?

  No well-established clinical herb–drug interactions are documented for Shan Dou Gen, but the absence of documented interactions is not evidence of safety here — it reflects how little formal interaction research has been done on a herb whose main literature is about poisoning. The reasonable precautionary points follow from its pharmacology rather than from interaction trials.

  • Liver-metabolised medication — matrine and oxymatrine are hepatically handled and this herb has documented hepatotoxicity in animal models. Concurrent use with hepatotoxic or narrow-margin hepatically cleared drugs is a matter for a practitioner. Precautionary, not a demonstrated interaction.
  • Central nervous system and respiratory depressants — given that the documented toxicity picture is neurological and respiratory, additive risk with agents acting on those systems is a sensible practitioner concern. Again precautionary.
  • Other matrine-bearing products — Ku Shen, and concentrated matrine or oxymatrine preparations, deliver the same alkaloids. This is the most realistic real-world overlap and the easiest one to miss.

  Anyone taking prescription medication should raise any herbal product with their doctor or pharmacist. (Flagged for practitioner confirmation.)

  Sources: PMID 33041782, PMC 7526649 (matrine pharmacokinetics and toxicology); PMID 39244176 (toxicology and attenuation review); PMID 36467100, PMC 9717682 (hepatotoxicity). Reference information, not medical advice.

Western / Biomedical Research

Chinese Herb Clinical Studies & Research

Provided as research context — a summary of published biomedical study, not a therapeutic or medical claim.

• Is there modern research on Shan Dou Gen (Sophora tonkinensis)?

  Yes, and it splits almost evenly into two halves — pharmacology and toxicology — because they concern the same molecules. A 2025 comprehensive review identified 333 chemical constituents in the root and rhizome, including 85 alkaloids and 124 flavonoids, and catalogued reported anti-inflammatory, antipyretic, analgesic, antibacterial, antifungal, antiviral, cardiovascular-protective, hepatoprotective and antitumour activities — while in the same breath documenting toxic effects on the liver, nerves, heart and gastrointestinal tract.

  • Quality markers — matrine and oxymatrine are the constituents by which this herb is assayed in the Chinese Pharmacopoeia. Following oral administration, matrine is the main species absorbed into circulation and is described as playing the major role in both the effects and the toxic effects of the herb.
  • Isolated-compound chemistry — new quinolizidine alkaloids continue to be isolated from this species and reported with anti-inflammatory activity in laboratory assays. Preclinical only.
  • Laboratory pharmacology — animal work reports protective effects of the water extract in chemically induced liver injury models, and separate studies report antitumour activity in cell models. These are cell and animal findings and do not establish clinical benefit.
  • Toxicology as an active research field — mechanistic studies of hepatotoxicity and pulmonary toxicity have been published using metabolomic, transcriptomic and systems-toxicology approaches. A dedicated safety review has been published on risk control for this herb specifically. Very few Chinese herbs have that literature.
  • The review authors’ own conclusion — the 2025 review concludes that the toxicity concerns must be addressed before clinical application is considered, and calls for further work on hepatotoxicity and neurotoxicity in particular.

  Honest summary: the pharmacology is real and actively studied; so is the harm. Nothing here is a recommendation to use this herb, and the research is presented as context for a medicine whose safety record is the most important thing about it.

  Sources: PMID 39244176, DOI 10.1016/j.jep.2024.118784 (comprehensive ethnopharmacology, phytochemistry, pharmacology, pharmacokinetics, toxicology and detoxification review); PMID 33622209, DOI 10.1142/S0192415X21500178 (pharmacological and toxicological review); PMID 31682871 (quinolizidine alkaloids and anti-inflammatory activity); PMID 36557783, PMC 9780913 (water extract in carbon-tetrachloride liver injury; Chinese Pharmacopoeia dose figure); PMID 36467100, PMC 9717682 (hepatotoxicity mechanism; matrine as the principal absorbed species); PMID 34333216 (pulmonary toxicity); PMID 33041782, PMC 7526649 (matrine systematic review); PMID 29271144 (safety evaluation and risk control). Research context, not a therapeutic claim.

Chinese Herb Notes

• What is the difference between Shan Dou Gen, Ku Shen and Bei Dou Gen?

  Shan Dou Gen and Ku Shen are different species of the same genus, Sophora, and both contain the alkaloids matrine and oxymatrine — but they are used for entirely different things. Bei Dou Gen is a third herb again, a “northern” counterpart named by contrast with Shan Dou Gen, and it is not a Sophora at all. The three names are muddled constantly, and because Shan Dou Gen is the toxic one of the group, the confusion matters.

  • Shan Dou Gen (this herb) — Sophora tonkinensis, root and rhizome. Bitter, cold; Large Intestine and Lung. A heat-clearing, toxin-eliminating herb for the swollen, painful throat. Carries documented acute toxicity.
  • Ku Shen — Sophora flavescens, root. Our own record gives it as bitter and cold with five channels (Bladder, Heart, Liver, Large Intestine, Small Intestine), used to clear damp-heat, kill parasites and stop itching, very often as an external wash. Same genus, same alkaloid family, different herb and different clinical territory.
  • Huai Hua Mi — also a Sophora in our records (Sophora japonica flower bud), but a blood-cooling, bleeding-stopping herb. A useful reminder that “Sophora” on a label tells you almost nothing on its own.
  • Bei Dou Gen — the “northern bean root,” named in opposition to Shan Dou Gen (“mountain bean root”). It is a distinct medicine from a different plant family and is not currently held in our own materia medica records, so we make no claims about it here beyond noting that it is a separate article and not a synonym.

  Where does the name Shan Dou Gen come from?

  Our record translates the name literally as “Mountain Bean Root.” Sophora tonkinensis is a legume — family Fabaceae, the bean family — and grows in south-central and southeastern China and northern Vietnam, which is also where the botanical epithet tonkinensis comes from. The name is descriptive of the plant, not of the action.

  Where it appears: in modern Chinese practice it is the core herb in several manufactured throat and liver preparations. Our own formula records do not currently link Shan Dou Gen to a classical formula, which is consistent with its use as a targeted single herb rather than a chief ingredient of the classical repertoire.

  Source: our own herb records (Shan Dou Gen name translation and identity; Ku Shen and Huai Hua Mi identity and channels), cross-referenced against multiple online sources and published materia medica consensus; distribution and modern preparations per PMID 39244176 and PMID 33622209.