Guan Zhong (Dryopteris Root)

Chinese Herb Actions

Chinese Herb Dosage

• What is the typical dosage of Guan Zhong?

  Commonly 4.5–9 g in decoction, with some materia medica allowing up to 15–16 g for stronger antiparasitic use. The charred form (Guan Zhong Tan) is used specifically for its blood-stopping action rather than for parasites. Because the herb is slightly toxic, doses at the upper end of the range are a professional-supervision decision, not a self-dosing guideline.

  Source: multiple online sources. Reference only — not a prescription.

Chinese Herb Contraindications & Cautions

• Are there cautions for Guan Zhong?

  Yes — Guan Zhong is classified as slightly toxic and is a professional-supervision herb. Traditional and modern sources agree it is contraindicated in pregnancy and should be used with caution in weak/deficient patients, children, and cases of pre-existing GI ulceration, cold-deficiency, or yin-deficiency patterns.

  • Do not combine with fatty/oily food — dietary fat markedly increases intestinal absorption of the herb’s toxic phloroglucinol compounds, raising toxicity risk (see Toxicity below).
  • Pregnancy — traditionally contraindicated; the herb has also been associated with stimulating uterine activity.
  • Dose ceiling & duration — stay within professionally supervised dosing; sources note prolonged use can dull taste/appetite and affect the gums.

  Source: materia medica cross-referenced against multiple online sources. Reference facts, not usage instructions.

Chinese Herb Toxicity & Overdose

• Slightly toxic (xiáo dú). The toxic principles are phloroglucinol derivatives — filicin (filmarone), filicic acids, flavaspidic acid, and dryocrassin. Under normal conditions these are poorly absorbed from the gut, but dietary fat substantially increases absorption, which is why fatty food must be avoided when the herb is taken (see Cautions).

  Reported overdose effects, from lower to higher exposure: headache, dizziness, nausea, vomiting, diarrhea, and abdominal pain; visual disturbance including yellow vision (xanthopsia) and, rarely, transient or even permanent blindness attributed to retinal/optic-nerve effects; and, in severe toxicity, muscle paralysis (including cardiac muscle), tremor, seizure, and respiratory failure.

  Note: This site’s toxic/endangered flag is currently unset for this herb, while materia medica consensus and the toxicology literature (PMID 38570147) classify Guan Zhong as slightly toxic. Flagged for owner review; not corrected here since this task only writes content fields.

  Source: cross-checked materia medica toxicity descriptions; PMID 38570147 (toxicology/pharmacokinetics review). Reference note, not a safety guarantee.

Herb-Drug Interactions

• No well-established clinical herb–drug interaction studies were found. Because the herb’s toxic phloroglucinol compounds are markedly more absorbed in the presence of dietary fat, practitioner caution is reasonable around anything that increases GI fat absorption or adds hepatic load; this is a precautionary inference from its known toxicology, not a demonstrated clinical interaction. (Flagged for practitioner confirmation.)

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 Guan Zhong (Dryopteris crassirhizoma)?

  Yes — mainly preclinical chemistry/pharmacology research supporting its traditional antiviral and antiparasitic reputation, plus one 2024 review of the whole evidence base. Dryopteris crassirhizoma’s phloroglucinol compounds (filicin-type constituents, dryocrassin ABBA, filixic acid ABA) are the most-studied active fraction.

  • Anti-influenza (H5N1), preclinical — a screen of twenty-three phloroglucinols from the rhizome identified dryocrassin ABBA and filixic acid ABA as neuraminidase inhibitors (IC50 ~18.6 and ~29.6 µM respectively), with dryocrassin ABBA also showing anti-H5N1 activity and low cytotoxicity in cell culture. Laboratory research, not clinical evidence.
  • Anticoronaviral, preclinical — the same two phloroglucinols inhibited the SARS-CoV-2 main protease and showed broad-spectrum activity against several coronaviruses in laboratory testing, with favorable preclinical safety/pharmacokinetic signals reported by the authors. Preclinical only.
  • Antioxidant / immunomodulatory polysaccharide, preclinical — an acidic polysaccharide fraction (DCP-3) isolated from the rhizome showed strong free-radical-scavenging activity and enhanced nitric-oxide production in macrophage cells, i.e. laboratory immune-cell evidence, not clinical proof.
  • Modern formula context — Mian Ma Guan Zhong (Rhizoma Dryopteridis Crassirhizomatis) is one of eleven herbal components of Lianhua Qingwen, a widely used contemporary multi-herb formula for influenza/respiratory infection, linking the herb’s classical epidemic-prevention use to current clinical practice. Formula-composition fact, not a treatment claim.
  • 2024 review — a comprehensive review of the plant’s botany, traditional use, phytochemistry, pharmacology, toxicology, and pharmacokinetics catalogued around 130 chemical constituents (phloroglucinols predominant) and confirmed documented antimicrobial, antiviral, anticancer, and anti-inflammatory activity, while noting the herb’s distinct toxicology profile warrants further characterization.

  All cited pharmacology is preclinical (cell/enzyme/animal-level); no human clinical trials of Guan Zhong itself were located.

  Sources: PMID 28282885, PMC 6155227 (anti-H5N1 phloroglucinol screening); PMID 35214108, PMC 8879496 (anticoronaviral activity against SARS-CoV-2 main protease); PMID 30797809 (polysaccharide antioxidant/immunomodulatory activity); PMID 34385103, PMC 8352581 (Lianhua Qingwen formula composition and mechanisms); PMID 38570147 (2024 botany/phytochemistry/pharmacology/toxicology review). Research context, not a therapeutic claim.

Chinese Herb Notes

• Is every herb sold as “Guan Zhong” the same plant?

  No — the recognized pharmacopeial source is Dryopteris crassirhizoma (Rhizoma Dryopteridis Crassirhizomatis, “Mian Ma Guan Zhong”), but rhizomes from several other fern genera — including Woodwardia, Osmunda, Matteuccia, and Cyrtomium — are also sold commercially under the “Guan Zhong” name. These botanical substitutes can differ in chemistry and toxicity from the official source, so confirming the actual species matters for both safety and expected effect.

  Modern formula context: Mian Ma Guan Zhong (Rhizoma Dryopteridis Crassirhizomatis) is one of the eleven herbal components of Lianhua Qingwen, a widely used modern multi-herb formula for influenza and respiratory infection — a contemporary echo of Guan Zhong’s classical role in epidemic-disease prevention. (Formula-composition fact, not a treatment claim.)

  Note: This site’s own record lists Guan Zhong’s Latin as “Rhizoma Guanchong” and its channels as Liver, Spleen. The research literature and most traditional materia medica sources instead use the pharmacopeial Latin “Rhizoma Dryopteridis Crassirhizomatis,” and channel entry is cited inconsistently across sources as Liver+Spleen or Liver+Stomach. We believe these all refer to the same herb; identity fields are left unchanged pending owner confirmation.

  Source: multiple online sources (botanical-source variability); PMID 34385103 / PMC 8352581 (Lianhua Qingwen formula composition).