Gan Sui (Kansui Root)

Chinese Herb Actions

Chinese Herb Dosage

• What is the dosage of Gan Sui?

  We do not publish a dose for Gan Sui. It is a toxic, drastic purgative whose margin between an effect and an injury is narrow, it is never used as raw material, and any legitimate use is a prescribing decision made by a licensed practitioner for an individual patient. Printing a number here would invite exactly the self-administration that the toxicology literature documents the harm of.

  What can be stated as neutral reference fact:

  • The raw root is not used as-is. Pharmacopoeial practice requires the root to be processed before any internal use; unprocessed kansui is irritant to skin, mouth and gastrointestinal tract. We describe the existence of processing, not how it is done.
  • It is not decocted in the ordinary way. The classical formulas containing it, such as Shi Zao Tang, do not boil it with the other ingredients — a structural fact about the formulas rather than a preparation instruction.
  • Use is short and exceptional. Harsh expellants were used for brief, decisive intervention in strong patients, never as maintenance therapy.

  Sources: materia medica consensus on the harsh-expellant category; PMID 27080940, DOI 10.1142/S0192415X16500154 (documented skin, oral and gastrointestinal irritation); PMID 31931159, DOI 10.1016/j.jep.2020.112557 (review establishing that processing changes kansui’s chemistry and activity). Reference facts only, not a prescription or a preparation guide.

Chinese Herb Contraindications & Cautions

• Is Gan Sui safe, and who should not use it?

  Gan Sui is not a safe herb by any ordinary reading of the word: it is classified toxic in its own identity record on this site, it is a drastic purgative, and it is contraindicated in pregnancy, in weak or deficient patients, and in anyone without an excess fluid-accumulation pattern. It is included here for completeness of the materia medica record and for exam study, not because it is a herb a reader should be seeking out.

  • Contraindicated in pregnancy — consistent with the harsh-expellant category as a whole, which is contraindicated in pregnancy without exception.
  • Contraindicated in deficiency — the classical requirement is a genuinely strong constitution with a true excess accumulation. In a weak patient the purgation itself is the injury.
  • Do not combine with Gan Cao — see the notes section above; this is both a classical prohibition and a pairing with measured experimental support.
  • Direct irritant — the 2016 pharmacology review documents skin, oral and gastrointestinal irritation from kansui constituents, which is why the raw material is not used as-is.
  • Professional-only — any use belongs to a licensed practitioner working with correctly processed, pharmacopoeial material, in an appropriate clinical setting.

  Sources: this site’s own identity record (toxic classification) and incompatibility records; materia medica consensus on the harsh-expellant category, cross-referenced against multiple online sources; PMID 27080940, DOI 10.1142/S0192415X16500154. Neutral safety reference, not usage instructions.

Chinese Herb Toxicity & Overdose

• High. Gan Sui is a documented irritant and hepatotoxin, and its toxicity comes from the same diterpene constituents that produce its purgative effect — the effect and the harm are not separable. A 2016 review of the herb records nearly 100 isolated compounds and identifies diterpenes and triterpenes as both the characteristic bioactive constituents and the source of its skin, oral and gastrointestinal irritancy.

  What the toxicology literature documents:

  • Irritant / corrosive action on mucosa — skin, oral and gastrointestinal irritation are the consistently reported acute effects, which is why unprocessed material is excluded from internal use.
  • Liver injury — a 2019 in-vivo study exposed zebrafish larvae to Euphorbia kansui at sub-lethal concentration and observed liver injury: altered liver microstructure, impaired hepatic function, changes in apoptosis-associated gene and protein expression, and significant metabolomic disturbance. The authors describe hepatotoxicity as the principal obstacle to the herb’s wider clinical use.
  • Toxicity is ratio- and combination-dependent — the kansui-licorice work described in the notes section showed toxicity indicators rising with the co-administered licorice dose, meaning the herb’s risk profile is not fixed but changes with what it is combined with.
  • Processing changes the chemistry — a 2020 review of the vinegar process documents that processing alters both the chemical composition and the biological activity of kansui. We note that this is established, and deliberately give no method.

  Sources: PMID 27080940, DOI 10.1142/S0192415X16500154; PMID 31132752, DOI 10.1016/j.phymed.2019.152959 (hepatotoxicity in zebrafish larvae in vivo); PMID 27084456, DOI 10.1016/j.jep.2016.04.012; PMID 31931159, DOI 10.1016/j.jep.2020.112557. Reference safety information, not a description of use.

• This herb is considered toxic.
  (while some Chinese herbs are toxic, it must be noted that many come prepared, or are combined, to mitigate their toxicity)

Herb-Drug Interactions

• No controlled clinical herb–drug interaction studies exist for Gan Sui. The best-characterised interaction is herb–herb rather than herb–drug: co-administration with licorice measurably reduced licorice-constituent bioavailability in rats and shifted the toxicity-efficacy balance unfavourably (see notes and toxicity sections). Because glycyrrhizin from licorice is itself present in very many herbal formulas and in some confectionery and supplements, that finding is a practical caution as well as a classical one.

  Given documented hepatotoxicity and a violent purgative action, concurrent use with hepatotoxic medication, with diuretics, or with any drug whose absorption or electrolyte balance would be disturbed by profound fluid loss is a reasonable theoretical concern. (Precautionary reference context flagged for practitioner confirmation, not a demonstrated clinical interaction list.)

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 Gan Sui (Euphorbia kansui)?

  Yes — an active phytochemical and pharmacological literature, concentrated on the diterpene constituents, on the toxicity-efficacy relationship, and on malignant effusion. There are no controlled human efficacy trials to report, and the research is context rather than evidence of benefit. A 2016 review counts nearly 100 identified compounds, with diterpenes and triterpenes as the characteristic bioactive class.

  • Chemistry — new constituents continue to be isolated, including a 2017 report of chemical constituents from Euphorbia kansui and a 2022 report of new jatrophane-type diterpenoids investigated as multidrug-resistance reversal agents in laboratory models.
  • Malignant effusion (animal) — the 2016 rat study of malignant pleural effusion found kansui had measurable effect on pleural fluid and urine volume, and mapped how that effect degraded as licorice was added. A 2023 study reported that vinegar-processed kansui combined with bile acids affected malignant ascites in an animal model, with gut-microbiota modulation proposed as the mechanism.
  • Virology (laboratory) — a 2016 PLoS One paper reported that Euphorbia kansui extract reactivates latent HIV in cell models, work relevant to the “shock and kill” research strategy. This is a laboratory finding about the plant’s diterpenes, and carries no implication for herbal use.
  • Toxicology — the zebrafish hepatotoxicity study described in the toxicity section is the clearest in-vivo characterisation, and the 2020 vinegar-process review is the main source on how processing changes the material.
  • Plant biology — a 2019 study profiled the microRNAome of Euphorbia kansui under methyl jasmonate treatment, part of work on the biosynthesis of its diterpenes.

  Overall: substantial preclinical chemistry and toxicology, a focused animal literature on effusion, and no human clinical evidence base. Research context, not a therapeutic claim.

  Sources: PMID 27080940, DOI 10.1142/S0192415X16500154; PMID 29292735, PMC 6150036, DOI 10.3390/molecules22122176 (chemical constituents); PMID 36156394, DOI 10.1002/cbdv.202200660 (jatrophane diterpenoids as MDR reversal agents); PMID 27084456, DOI 10.1016/j.jep.2016.04.012; PMID 38026948, PMC 10665909, DOI 10.3389/fphar.2023.1249910 (vinegar-processed kansui and bile acids in malignant ascites); PMID 27977742, PMC 5158021, DOI 10.1371/journal.pone.0168027 (latent HIV reactivation, in vitro); PMID 31132752, DOI 10.1016/j.phymed.2019.152959; PMID 31931159, DOI 10.1016/j.jep.2020.112557; PMID 30871196, PMC 6471261, DOI 10.3390/ijms20061267 (microRNAome). Research context, not a therapeutic claim.

Chinese Herb Notes

• Why can Gan Sui not be combined with Gan Cao (licorice)?

  Gan Sui and Gan Cao are one of the classic “Eighteen Incompatibilities” (shi ba fan) pairs — the oldest and best-known list of herb combinations Chinese medicine treats as forbidden. Our own incompatibility records hold this pair, and hold Gan Cao as incompatible with four others in the same tradition: Jing Da Ji, Da Ji, Hai Zao and Yuan Hua. Three of those five — Gan Sui, Jing Da Ji and Yuan Hua — are the harsh expellants.

  Modern work has tested the pairing rather than simply repeating it, and the results support the classical warning:

  • Licorice made kansui more toxic and less effective. A 2016 study in rats with malignant pleural effusion measured toxicity and efficacy indicators across kansui-to-licorice ratios from 4:1 down to 0.1:1. Toxicity rose as the licorice dose rose, while efficacy fell; the crossover point sat between the 2:1 and 1:1 ratios. The authors concluded the co-use weakens the effect and can produce serious toxicity at the wrong ratio.
  • There is a measurable pharmacokinetic mechanism. A 2018 study tracking five licorice constituents in rat plasma found that Gan Sui decreased the bioavailability of Gan Cao, while Bai Shao increased it — offered as an explanation both for the incompatibility and for why the historical Gan Sui Ban Xia Tang, which contains both, was nonetheless composed the way it was.

  The one classical exception is instructive, not permissive. Gan Sui Ban Xia Tang is the well-known formula in which the forbidden pair appears together deliberately, at a specific ratio, with Ban Xia and Bai Shao. It is cited in the literature as the exception that proves how ratio-dependent the interaction is — not as licence to combine the two herbs freely.

  Formulas on this site containing Gan Sui: Shi Zao Tang (Ten Jujube Decoction), Zhou Che Wan (Vessel and Vehicle Pill) and Da Xian Xiong Tang (Major Sinking Into the Chest Decoction) — all severe, excess-pattern formulas presented on this site as historical and reference entries.

  Sources: incompatibility pairs recorded on this site; PMID 27084456, DOI 10.1016/j.jep.2016.04.012 (dosage-toxicity-efficacy of kansui and licorice); PMID 30015102, DOI 10.1016/j.jpba.2018.07.014 (pharmacokinetics of the Gansui-Gancao pair and Gansuibanxia decoction); formula composition records held on this site.

This herb is incompatible with:

• Gan Cao (Radix Glycyrrhizae)

This herb is considered toxic