Er Cha (Paste from Dried Conc. Decoction of Black or Brown Cutch, Catechu, Gambier)

Chinese Herb Actions

Chinese Herb Dosage

• What is the typical dosage of Er Cha?

  Er Cha is used mainly topically, with no fixed weight since it is dusted or worked into a paste directly on the affected area rather than measured for ingestion. When taken internally, standard materia medica references give roughly 1–3 g decocted — typically wrapped in cloth because the paste does not fully dissolve — or about 0.3–1 g when taken as pills or powder (some references give a slightly lower pill/powder range of ~0.1–0.9 g).

  Source: cross-referenced against multiple online sources. Reference only — not a prescription.

Chinese Herb Contraindications & Cautions

• Are there cautions for Er Cha?

  Er Cha is traditionally contraindicated, or used with caution, in patterns of Cold with Dampness — its cooling, drying, strongly astringent nature can aggravate cold-type presentations. As with other astringent hemostatics, it is best used under a qualified practitioner, and topical use on any wound that is still actively infected or draining should be professionally assessed rather than self-treated.

  Note on a commonly repeated claim: several herb references state that Er Cha is “banned or restricted in the UK” under the MHRA’s list of banned/restricted herbal ingredients. Checking the primary MHRA source directly, the entry that exists is for Areca catechu (betel nut, a palm-family stimulant restricted to pharmacy sale) — an unrelated plant that happens to share the species epithet “catechu.” No entry for Acacia catechu or Uncaria gambir (the actual sources of Er Cha) was found on the current MHRA list. We treat the “UK-banned” claim as a likely naming mix-up and have not repeated it as fact.

  Source: multiple online sources Cold-Damp contraindication (cross-referenced); UK Government banned/restricted herbal ingredients list (gov.uk), checked directly for the discrepancy note above.

Chinese Herb Toxicity & Overdose

• Traditional dosing has a long history of use with no significant acute toxicity reported, and a 28-day sub-acute animal toxicity study of an Acacia catechu seed extract found no deaths, no significant body-weight or organ-weight changes, and no hepatotoxic or nephrotoxic enzyme changes at doses up to 1000 mg/kg. That said, a 2022 pharmacognosy review of Acacia catechu explicitly flags a data gap: human clinical toxicity and safety-trial data remain limited.

  Separately, a published case report describes acute hepatitis in a patient taking a combination supplement containing Chinese skullcap (Scutellaria baicalensis) and black catechu for joint pain; the clinicians attributed the liver-enzyme abnormalities mainly to the skullcap component, with catechu’s contribution unclear. A related U.S. LiverTox entry (for the skullcap/catechu combination product flavocoxid) separately notes that Acacia catechu (catechin) has been implicated in rare, idiosyncratic acute liver injury by an unknown mechanism, without isolating its individual frequency or severity. These are reference safety signals from combination-product case data, not a demonstrated risk from Er Cha used alone at traditional doses.

  Source: PMID 32169672 (sub-acute toxicity, Wistar rat); PMID 36432824 / PMC 9697042 (bioactive-compound review noting the human safety-data gap); PMID 27144042 / PMC 4842037 (skullcap + black catechu case report); PMID 31643459 / NCBI Bookshelf NBK548129 (LiverTox, flavocoxid/Acacia catechu). Reference note, not a safety guarantee.

Herb-Drug Interactions

• Er Cha is very rich in tannins, and tannins are well established to bind dietary and supplemental iron in the gut, reducing its absorption — as a precaution, separating Er Cha from oral iron supplements or iron-fortified meals by roughly two hours is a reasonable, general tannin-iron precaution rather than a demonstrated Er Cha-specific clinical trial finding. Tannin-rich substances can also bind and reduce the absorption of some other oral medications in the gut; no specific drug has been clinically confirmed to interact with Er Cha, so this is flagged for practitioner awareness rather than a documented interaction. (Flagged for practitioner confirmation.)

  Source: general tannin–iron chelation pharmacology (PMC 5525358 review); no Er Cha–specific clinical interaction trial identified.

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 Er Cha (Acacia catechu / Uncaria gambir)?

  Yes — mostly preclinical (animal and cell-based) pharmacology on both botanical sources, with human clinical evidence still limited. Chemically, both sources are exceptionally tannin-rich: reviews report catechuic acid/tannin content around 25–33% in Acacia catechu heartwood, and combined catechin/tannin content upward of 60% in Uncaria gambir (gambier) extract.

  • Wound healing (Uncaria gambir, preclinical) — catechu extract from gambir stimulated angiogenic (blood-vessel-forming) activity in zebrafish-embryo and cell-based assays, upregulating genes involved in tissue repair, offering a mechanistic rationale for its traditional use on non-healing wounds; animal/cell-model evidence, not a clinical trial.
  • Wound healing (Acacia catechu, diabetic mice, preclinical) — a combined topical gel plus oral bark-extract treatment achieved substantially faster wound closure than controls in streptozotocin-induced diabetic mice, with molecular docking suggesting the marker compound (−)-epicatechin as a contributor; animal/computational evidence, not human data.
  • Antidiarrheal (Uncaria gambir fraction, preclinical) — a bioactive tannin-containing fraction of gambir dried-sap extract reduced progression to severe diarrhea and intestinal fluid accumulation in a castor-oil rat model, performing comparably to loperamide; a rat study supporting, but not proving, the traditional astringent/antidiarrheal use.
  • Bioactive-compound review (Acacia catechu) — a 2022 review confirms substantial antibacterial activity (including against Streptococcus mutans) and antioxidant activity across extracts, while explicitly noting that human toxicity and clinical-trial data remain limited.

  Overall: consistent, multi-study preclinical support for the traditional wound-healing, astringent, and antidiarrheal uses, but no controlled human clinical trials of Er Cha itself were identified.

  Sources: PMID 36678562, PMC 9863412, DOI 10.3390/ph16010066 (Uncaria gambir wound healing, zebrafish/in vitro); PMID 37693096, PMC 10492149, DOI 10.1016/j.jtcme.2023.05.001 (Acacia catechu wound healing, diabetic mice); PMID 34290534, PMC 8289365, DOI 10.2147/JEP.S299001 (Uncaria gambir antidiarrheal, Wistar rats); PMID 36432824, PMC 9697042, DOI 10.3390/plants11223091 (Acacia catechu bioactive-compound review). Research context, not a therapeutic claim.

Chinese Herb Notes

• What are Er Cha’s two botanical sources, and how does it combine with other herbs?

  Er Cha is prepared from two different plants reduced to a dried paste, which is why its Latin name reads “Pasta Acaciae Seu Uncariae” (paste of Acacia or Uncaria). The current Chinese Pharmacopoeia designates Acacia catechu (Fabaceae) heartwood — boiled down for roughly 12 hours into “black” or “brown” cutch — as the official source. Uncaria gambir (Rubiaceae) leaf and young-twig extract — boiled down over a shorter period (traditionally a few hours) into “gambier” or “pale catechu” — is a long-used alternate/regional source, especially from Southeast Asia. Both are extremely tannin-rich pastes used interchangeably in practice.

  Common combinations:

  • Xue Jie (Dragon’s Blood) — for traumatic injury with bleeding and bruising; Xue Jie adds blood-invigorating, pain-relieving action alongside Er Cha’s hemostatic, flesh-generating effect.
  • San Qi (Notoginseng) — for bleeding, especially upper digestive tract bleeding, combining two hemostatics with different mechanisms.
  • Bai Ji (Bletilla) — for traumatic hemorrhage; Bai Ji is more mucilaginous and better suited to internal ulceration, while Er Cha is the more classically topical of the two.
  • Bing Pian (Borneol) — for chronic, non-healing sores and ulcers.
  • Peng Sha (Borax) — for mouth sores and gum disease.

  In this site’s own record, Er Cha appears in Qi Li San (a classical trauma formula that invigorates blood and stops bleeding); other TCM references also place it in topical preparations such as Jin Chuang Gao (Golden Sore Ointment) and Zheng Gu Zi Jin Dan. (Traditional formula context, not treatment advice.)

  Source: this site’s own record (formula link); multiple online sources pharmacognosy reference (botanical sourcing/preparation).