Tong Cao (Rice Paper Pith, Tetrapanax)

Chinese Herb Actions

Chinese Herb Dosage

• What is the typical dosage of Tong Cao?

  Roughly 2–5 g in decoction — our reference record carries 2–5 g, and a second published range of 2–4.5 g, with a much larger 15–18 g recorded specifically for promoting lactation. The gap between the two figures is real and deliberate: the everyday draining dose is small, while the traditional lactation use calls for a far larger amount of what is an extremely light, low-density material.

  • Why the doses look small — Tong Cao is pith, not root or bark. It is spongy and almost weightless, so a few grams is a substantial volume of herb.
  • The large lactation dose is a traditional record, not a recommendation — it is listed here for reference completeness. Postpartum and lactation dosing is a matter for a qualified practitioner.

  Source: Sacred Lotus dosage record (2–5 g in decoction, or 15–18 g to promote lactation; 2–4.5 g in decoction from the second cited reference). Reference only — not a prescription.

Chinese Herb Contraindications & Cautions

• Is Tong Cao safe, and are there cautions?

  Tong Cao is contraindicated in pregnancy in our reference record, and is used with caution where there is cold in the middle burner. It is otherwise regarded as a mild herb with no notable intrinsic toxicity. The one safety point that genuinely needs stating is a naming point rather than a property of the herb itself.

  • Pregnancy — contraindicated.
  • Middle-burner cold — use caution; it is cold and draining, however mildly.
  • Draining herbs and fluids — as with the category generally, prolonged or heavy use of urination-promoting herbs is inappropriate where fluids or yin are already depleted.
  • Identification (the real safety issue) — Tong Cao is Tetrapanax papyrifer pith and contains no aristolochic acid. The aristolochic-acid risk belongs to Aristolochia species — notably Aristolochia manshuriensis, traded as Guan Mu Tong, and Aristolochia fangchi, which was substituted for a Fang Ji herb in the Belgian cases that first brought “Chinese herbs nephropathy” to international attention. Aristolochic acid is an IARC Group 1 human carcinogen; population studies in Taiwan have linked consumption of herbal products suspected of containing it to urothelial cancer, and a characteristic mutational signature has been traced in affected tumours. Species-level identification of purchased material is therefore a legitimate question to put to any supplier — DNA-based tests for Aristolochia contamination of herbal products have been developed for exactly this purpose.

  Stated plainly, in both directions: Tong Cao itself is not implicated in aristolochic acid nephropathy, and it should not be avoided on that basis. Equally, the aristolochic-acid problem in Aristolochia-sourced material is serious, well documented, and not something to soften.

  Source: Sacred Lotus cautions record (pregnancy; caution with Middle Jiao cold); IARC Group 1 classification and aristolochic acid sources per PMID 31244661, PMC 6580798, DOI 10.3389/fphar.2019.00648; Belgian “Chinese herbs nephropathy” evidence review per PMID 12495362, DOI 10.2165/00002018-200326010-00004; Taiwan urothelial cancer epidemiology per PMID 22493262, PMC 3361449, DOI 10.1073/pnas.1119920109 and PMID 25170766, PMC 4149424, DOI 10.1371/journal.pone.0105218; mutational signature per PMID 23422071; DNA detection of Aristolochia contamination per PMID 30619401, PMC 6297175, DOI 10.3389/fpls.2018.01828. Neutral reference facts, not usage instructions.

Chinese Herb Toxicity & Overdose

• Is Tong Cao toxic?

  Tong Cao is not classified as a toxic herb, and our reference record does not flag it as toxic or endangered. It is a light plant pith with a long record of use at small doses and no reported intrinsic toxicity in the standard materia medica. It contains no aristolochic acid — that compound class belongs to Aristolochia, an unrelated plant genus, as set out in the cautions section above.

  Source: Sacred Lotus record (not flagged toxic/endangered); materia medica consensus (Bensky 3rd ed.; Chen & Chen), cross-referenced against multiple online sources. Reference note, not a safety guarantee.

Herb-Drug Interactions

• Does Tong Cao interact with medications?

  No well-established clinical herb–drug interactions are documented for Tong Cao. Research on the herb is sparse, so this reflects absence of study rather than proven absence of interaction. A general precaution applies to any urination-promoting herb used alongside diuretic medication, and readers who are pregnant, breastfeeding, or taking prescription medicines should have herbal use reviewed by a qualified practitioner. (Precautionary; no demonstrated clinical interaction.)

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 Tong Cao (Tetrapanax papyrifer)?

  Very little — Tetrapanax papyrifer is one of the least-studied herbs in its category, with only a handful of indexed papers and no clinical trials. What exists is chemistry, botany, and one ethnobotanical survey that supports its continuing role as a lactation herb.

  • Contemporary use as a galactagogue — a survey of 90 lactation-promoting prescriptions collected from 87 traditional pharmacies in Taiwan identified Tetrapanax papyrifer as a core medicinal material, second only to Angelica sinensis. This documents prescribing practice, not efficacy.
  • Essential oil chemistry — 61 compounds were identified by GC-MS/GC-FID, with sesquiterpenoids making up about 96% of the oil (chiefly β-cubebene, caryophyllene and α-cubebene). The oil showed dose-dependent antioxidant activity in DPPH, ABTS and FRAP assays and weak α-glucosidase inhibition (about 18% at 500 µg/mL). In vitro only.
  • Botanical identity — the chloroplast genome of Tetrapanax papyrifer has been sequenced and placed phylogenetically within Araliaceae, the ginseng and ivy family — taxonomically remote from Aristolochia (Aristolochiaceae), Clematis (Ranunculaceae) and Akebia (Lardizabalaceae). This is the sequencing-level confirmation behind the identity distinctions above.

  No human clinical evidence exists for this herb. The material above is chemistry, botany and prescribing-practice data, offered as scientific context rather than as a therapeutic claim.

  Sources: PMID 33679390, DOI 10.3389/fphar.2020.625869 (galactagogue prescribing survey, Taiwan); PMID 39714382, DOI 10.1002/cbdv.202402533 (essential oil composition and in vitro activity); PMID 41646198, PMC 12872081, DOI 10.1080/23802359.2026.2621456 (chloroplast genome and Araliaceae placement). Research context, not a therapeutic claim.

Chinese Herb Notes

• What is the difference between Tong Cao and Mu Tong — and is Tong Cao the one with aristolochic acid?

  No. Tong Cao is not the aristolochic-acid herb, and it is not the same plant as Mu Tong. Tong Cao is the pith of Tetrapanax papyrifer (family Araliaceae). Mu Tong is a woody stem from an entirely different plant — in our own reference, Clematis armandii (Chuan Mu Tong), with Akebia species also accepted. The aristolochic-acid problem attaches to Aristolochia species that were historically traded under Mu Tong names, above all Guan Mu Tong (Aristolochia manshuriensis). That is a third plant again, and neither Tong Cao nor Clematis-source Mu Tong is it.

  Tong Cao vs Mu Tong, as a differentiation:

  • Both unblock and promote urination, and both are traditionally used to promote lactation.
  • Tong Cao — sweet, bland, slightly cold; Lung and Stomach. Mild. Our record puts it plainly: it is not as bitter as Mu Tong, so its effect is less powerful, and it suits milder damp-heat or is combined with stronger herbs for more severe cases.
  • Mu Tong (Chuan Mu Tong) — bitter, cold, bland; Bladder, Heart and Small Intestine. Stronger and more draining, and distinguished by clearing Heart fire downward through the small intestine — mouth and tongue sores with irritability and scanty urine. Tong Cao does not have that Heart-fire action.
  • Practical upshot — they are not interchangeable, and a substitution in either direction changes both the strength and the target of a formula.

  Why the confusion matters: the similar names have real consequences. Aristolochic acid, found in Aristolochia species, is classified by the International Agency for Research on Cancer as a Group 1 human carcinogen and is the established cause of aristolochic acid nephropathy — a progressive kidney interstitial fibrosis — and of urothelial carcinoma. Six aristolochic acids have been isolated and characterised from Aristolochia manshuriensis stems, the material sold as Guan Mu Tong. Both Tong Cao and Clematis-source Mu Tong are botanically unrelated to Aristolochia and are not sources of aristolochic acid. Because the historical problem arose from name-based substitution rather than from any one herb, the honest guidance is to check the botanical source on the label, not the pinyin name. See the cautions section for the detail.

  Source: Sacred Lotus identity and comparison records for Tong Cao and for Mu Tong / Chuan Mu Tong (including its note that Mu Tong may be sourced from Akebia or Clematis); IARC Group 1 classification and material sources per PMID 31244661, PMC 6580798, DOI 10.3389/fphar.2019.00648; aristolochic acids isolated from Aristolochia manshuriensis per PMID 31685246; family placement of Tetrapanax papyrifer in Araliaceae per PMID 41646198, DOI 10.1080/23802359.2026.2621456.