Bei Xie (Fish Poison Yam Rhizome, Tokoro)

Chinese Herb Actions

Chinese Herb Dosage

• What is the typical dosage of Bei Xie?

  Our record gives 10–15 g in decoction from one reference and 9–15 g from another — effectively the same standard range, with the small difference reflecting different source texts rather than a genuine disagreement. The rhizome is sliced and decocted with the other herbs in the usual way; no special preparation is required.

  • Decoction — 9–15 g (one of our cited references gives 10–15 g).
  • Part used — the rhizome, sliced and dried.
  • Course length — see notes: this herb is traditionally described as slow-acting, which affects how long it is given rather than how much.

  Source: our own herb record dosage entries and their cited references, cross-referenced against multiple online sources. Reference only — not a prescription.

Chinese Herb Contraindications & Cautions

• Are there cautions for Bei Xie?

  Our record advises caution in Kidney yin deficiency, in yin deficiency with blazing fire, and in terminal dripping of urine where dampness is present. The reasoning is that this is a draining, dispersing herb: it moves dampness out through the urine, and in a patient whose fluids are already depleted that drainage can deepen the deficiency rather than help it.

  • Kidney yin deficiency — use with caution; the drying, draining action can further consume yin.
  • Yin deficiency with blazing fire — use with caution, for the same reason.
  • Terminal dripping of urine with dampness present — use with caution per our record.
  • Slow onset — not a caution as such, but relevant to safe use: because its effects are described as gradual, there is a temptation to escalate the dose. Dose escalation beyond the standard range is not supported.
  • Correct species — because several Dioscorea species supply this herb (see notes), material identity varies; properly identified product matters.

  Source: our own herb record caution entry, cross-referenced against multiple online sources. Reference information, not medical advice.

Chinese Herb Toxicity & Overdose

• None Noted

Herb-Drug Interactions

• None Noted

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 Bei Xie (Rhizoma Dioscoreae Hypoglaucae)?

  Yes — and the modern research clusters tightly around uric acid and gout, which maps onto the traditional “turbid dampness in the lower burner” picture with unusual neatness. The work is preclinical: enzyme assays, cell models and rodent models of hyperuricemia. No human clinical evidence is presented here, and none of this constitutes a treatment recommendation.

  • Xanthine oxidase inhibition — comparing Dioscoreae Hypoglaucae Rhizoma and Dioscoreae Spongiosae Rhizoma by chemical fingerprint and spectrum–effect analysis, researchers identified four steroidal saponins (protodioscin, protogracillin, methyl protodioscin and pseudoprogracillin) as the constituents most correlated with xanthine oxidase inhibition, validated by enzyme assay and molecular docking. Xanthine oxidase is the enzyme targeted by conventional urate-lowering drugs.
  • Hyperuricemia in animals — a purified polysaccharide from Dioscorea septemloba lowered serum uric acid in a hyperuricemic mouse model by inhibiting xanthine oxidase and modulating urate transporter expression (GLUT9, OAT1, OAT3, URAT1, ABCG2), while reducing kidney and liver damage. Mouse model only.
  • Crystal-induced inflammation — total saponins of Dioscorea collettii attenuated monosodium urate crystal-induced inflammation in a laboratory model by inhibiting TLR4/NF-κB signalling — the pathway underlying an acute gout attack.
  • Anti-inflammatory saponins — steroidal saponins purified from Dioscoreae Hypoglaucae Rhizoma by macroporous resin have been evaluated for anti-inflammatory effect, consistent with the herb's traditional use for painful obstruction and damp-heat skin lesions.
  • Tokoro material — steroidal saponins isolated from the rhizome of Dioscorea tokoro have been shown to inhibit cell growth and autophagy in hepatocellular carcinoma cell lines. A cell-line finding about the Japanese species, not a claim about this herb in patients.

  Taken together, the chemistry gives a coherent story — steroidal saponins, xanthine oxidase inhibition, urate handling — but the studies are laboratory and animal work. The traditional indications above stand on traditional grounds, not on this research.

  Sources: PMID 38138603, PMC 10745721, DOI 10.3390/molecules28248116 (xanthine oxidase inhibitors of the two Bi Xie drugs); PMID 39489240, DOI 10.1016/j.ijbiomac.2024.137112 (D. septemloba polysaccharide in hyperuricemic mice); PMID 34721647, PMC 8550844 (total saponins of D. collettii, urate-crystal inflammation); PMID 40829486, DOI 10.1016/j.jchromb.2025.124769 (steroidal saponins, anti-inflammatory evaluation); PMID 34440493, PMC 8400091 (D. tokoro steroidal saponins, hepatocellular carcinoma cell lines). Research context, not a therapeutic claim.

Chinese Herb Notes

• Should it be spelled “Bei Xie” or “Bi Xie”?

  Both spellings refer to the same herb, and “Bi Xie” is the more standard romanisation. The Chinese name is 萆薢, romanised in pinyin as bì xiè. Our record carries “Bei Xie” as the primary spelling with “Bi Xie” recorded as an alternate name — and our own tone-marked field already reads bì xiè, so the record is internally inconsistent. Separately, our record writes the characters as 荜解, while the herb is standardly written 萆薢. We are flagging both rather than silently changing them: readers who search either spelling are looking at the same medicinal, and the identity fields are left unchanged pending owner confirmation.

  What plant does Bei Xie actually come from?

  More than one — this is a genuinely multi-sourced herb. Our record gives the Latin as Rhizoma Dioscoreae Hypoglaucae and the common names as fish poison yam rhizome and tokoro. In practice several Dioscorea species supply the market, and modern Chinese standards recognise two distinct drugs under the one traditional name:

  • Fen Bi Xie — Dioscoreae Hypoglaucae Rhizoma, from Dioscorea hypoglauca (also treated as D. collettii var. hypoglauca). This is the source our record names.
  • Mian Bi Xie — Dioscoreae Spongiosae Rhizoma, from Dioscorea spongiosa and Dioscorea septemloba. Chemical fingerprinting shows the two drugs are distinguishable by their steroidal saponin profiles (protodioscin, protogracillin, dioscin and gracillin as discriminating markers), while sharing overlapping activity.
  • Tokoro — the common name in our record is the Japanese name for Dioscorea tokoro, a related species used in Japan. It is studied separately in the modern literature and should not be assumed identical to the Chinese material.
  • Not to be confused with — Shan Yao (Dioscorea opposita), the sweet, tonifying Chinese yam, which is the same genus but an entirely different medicinal with the opposite therapeutic role.

  How is Bei Xie used in formula?

  Its signature formula is Bei Xie Fen Qing Yin — “Dioscorea Hypoglauca Decoction to Separate the Clear” — where it is combined with Yi Zhi Ren, Wu Yao and Shi Chang Pu to warm the Kidney yang, dispel cold from the lower burner and restore the separation of clear fluid from turbid. For the damp-heat version of the same complaint it is instead paired with cooling, damp-draining herbs such as Huang Bai and Che Qian Zi.

  Our record also carries a practical observation worth keeping: some practitioners find this herb's effects gradual, becoming noticeable only after several weeks, which makes it better suited to chronic painful obstruction than to an acute flare. (Traditional formula context, not treatment advice.)

  Source: our own herb and formula records (Latin, common names, alternate name, tone-marked pinyin, formula composition), cross-referenced against multiple online sources; two-drug distinction and saponin markers per PMID 38138603, PMC 10745721.