Traditionally used for
- Teeth & mouth
- Cough & breathing
- Bowel health
- Skin
Cautions & contraindications
- Liver conditions
☯ TCM Properties
Stops bleeding and promotes tissue regeneration; Absorbs Dampness and Heals Sores; Invigorates Blood and Alleviates Pain; Clears Lung Heat and Transforms Phlegm
Traditional Chinese Uses
Er Cha (black catechu, cutch extract) is a cool, bitter-astringent substance derived from acacia heartwood extract. In Chinese medicine, it clears Lung Heat, resolves Phlegm, stops bleeding, and relieves pain. Applied topically, it treats aphthous ulcers, eczema, bleeding gums, and chronic non-healing wounds. Internally, it is used for cough with yellow phlegm and diarrhea from Damp-Heat. Its strong astringent and antimicrobial properties make it effective for damp, inflamed conditions of both skin and mucous membranes.
Western Herbalism Properties
Relationships
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Botanical Description
Acacia catechu (L.f.) Willd. (Fabaceae), known as khadira or cutch, is a small to medium deciduous tree 9-15 m tall native to South and Southeast Asia, with feathery bipinnate leaves, paired stipular thorns, and pale yellow cylindrical flower spikes followed by flat brown pods. The medicinal Er Cha (catechu, cutch) is a dark brown to black, brittle extract prepared by boiling chips of the dark red heartwood in water and evaporating the decoction to dryness. The extract is exceptionally rich in catechin and epicatechin tannins (50-60%), giving it strong astringent and antioxidant properties. In traditional Chinese medicine, Er Cha is bitter, astringent, and cool, entering the heart and lung channels; it clears heat, transforms phlegm, generates flesh, and stops bleeding, applied topically for non-healing wounds, mouth sores, and skin ulcers, and internally for chronic cough with phlegm. It is also a foundational Ayurvedic remedy for skin and oral diseases.
Active Constituents
(+)-Catechin
Flavan-3-ol (flavonoid)Concentration: highly variable with grade and assay; quantified at about 31.5 mg/g in one standardised heartwood extract, while figures as high as 66.9% of a dried bark/heartwood extract are reported for well-made katha
The principal antioxidant and astringent principle of the drug, and the constituent standardised in the Acacia catechu extracts used in commercial preparations. It scavenges reactive oxygen species and inhibits 5-lipoxygenase and cyclooxygenase pathways in vitro, which is the stated rationale for the anti-inflammatory use of catechu-based products.
(-)-Epicatechin
Flavan-3-ol (flavonoid)Concentration: about 12.5 mg/g in one quantified heartwood extract; up to roughly 23% reported for concentrated bark extracts
The catechin epimer, present at roughly a third to a half of the catechin level in most analyses. It contributes to the same antioxidant and astringent profile and is one of the two compounds by which black catechu is routinely identified analytically.
Catechutannic acid (condensed proanthocyanidin tannins)
Condensed tannin (proanthocyanidin)The polymeric tannin fraction formed by condensation of the flavan-3-ols during the traditional boiling-down of the heartwood decoction. It is responsible for the drug's marked astringency and for its topical haemostatic and tissue-drying action, and it is the fraction that binds dietary and supplemental iron and other cations in the gut.
Epicatechin gallate and epigallocatechin gallate
Galloylated flavan-3-olMinor galloylated catechins reported in heartwood extracts. They are the structural class most associated with concentration-dependent hepatocyte stress in the wider green-tea catechin literature, which is relevant background to the liver-injury signal seen with concentrated Acacia catechu products.
Quercetin
FlavonolA flavonol recovered from the heartwood alongside kaempferol-type compounds. It is a broad antioxidant and an inhibitor of several drug-metabolising enzymes in vitro, though its concentration in commercial catechu is not consistently quantified across published analyses.
Taxifolin (dihydroquercetin)
Flavanonol (dihydroflavonol)A characteristic dihydroflavonol of the heartwood and a biosynthetic precursor of the catechins. It is used together with catechin and epicatechin as a chemical fingerprint for authenticating Acacia-derived catechu.
Gallic acid and protocatechuic acid
Phenolic acidSimple phenolic acids present in the extract, contributing antioxidant capacity and adding to the total phenolic load measured in quality-control assays.
Lupeol and lupenone
Pentacyclic triterpenoid (lupane type)Non-phenolic triterpenoids of the heartwood, reported with anti-inflammatory activity in vitro. They are minor components and are not used for standardisation.
⚠ Drug Interactions
Uncaria gambir (gambier, pale or square catechu, Fang Er Cha)
Two unrelated plants are sold internationally as "catechu". Black catechu (cutch, Hei Er Cha) is the boiled-down aqueous extract of Acacia catechu heartwood and is the species specified by the Chinese Pharmacopoeia for Er Cha. Pale or brown catechu, gambier, is the extract of the leaves and twigs of Uncaria gambir and is traded in China as Fang Er Cha, distinguishable in the raw state as neat dull-brown cubes rather than the glossy dark irregular mass of the Acacia product. The two share catechin and epicatechin, so a simple catechin assay will not separate them, but gambier additionally carries Uncaria indole alkaloids such as gambirine and gambirtannine that are absent from Acacia. The US Pharmacopoeia historically dropped Acacia catechu in favour of gambier precisely because gambier was more uniform, which is why the substitution is entrenched in the Western supply chain.
Clinical note: Specify Acacia catechu heartwood extract when ordering and check the morphology of the raw drug: dark, glossy, brittle and irregular for the correct Acacia product, uniform brown cubes for gambier. Do not accept a certificate of analysis that reports only total catechins.
Acetaminophen, methotrexate, isoniazid and other hepatotoxic drugs or supplements
Concentrated Acacia catechu extract is one of the two components of flavocoxid (marketed as Limbrel), the other being Scutellaria baicalensis. The Drug-Induced Liver Injury Network identified four cases of acute liver injury attributed to flavocoxid among 877 prospectively enrolled patients, all developing within one to three months of starting the product. In November 2017 the US FDA advised consumers to stop using Limbrel after 194 adverse event reports, and requested a recall in December 2017; the events included drug-induced liver injury and hypersensitivity pneumonitis. The mechanism is idiosyncratic and not established, and the injury cannot be attributed to the Acacia component rather than the Scutellaria component on present evidence, but the catechu extract cannot be excluded as the culprit and must be treated as a potential hepatotoxin at concentrated doses.
Clinical note: Traditional topical and small-dose internal use of raw Er Cha has not been implicated. The signal attaches to concentrated standardised extracts taken daily for months. Do not stack a concentrated Acacia catechu product with other hepatically stressful agents, and check liver enzymes if such a product is continued beyond a few weeks.
Oral iron salts (ferrous sulfate, ferrous fumarate) and other divalent cation supplements
Catechu is a tannin-dominated drug; the condensed proanthocyanidin fraction chelates non-haem iron and other divalent cations in the gut lumen and forms insoluble complexes, the same mechanism by which strong tea impairs iron absorption. The interaction is compounded by a historical quality problem specific to this drug: commercial catechu has been documented as adulterated with 60 to 65 percent ferrous carbonate, so an iron-adulterated sample confounds any attempt to reason about iron status while the patient is taking it.
Clinical note: Separate oral iron and any tannin-rich catechu preparation by at least two hours. If a patient on catechu has unexplained iron findings, consider adulteration of the raw drug as well as the pharmacological interaction.
Dosage
| Form | Amount | Frequency | Duration | Population | Notes |
|---|---|---|---|---|---|
| decoction, or powder/pills | 1–3 g | Daily | — | — | 中国药典 2020 【用法与用量】1～3g，包煎；多入丸散服。外用适量。 【性味与归经】苦、涩，微寒。归肺、心经。 — Chinese Pharmacopoeia 2020, quoted verbatim; route and cautions preserved. Replaces a cleared category-filler value. |
Evidence Tier
Moderate evidence · 2 studiesRecorded studies by study design, strongest design at the top. This is a study-design tier only, not a GRADE rating: it does not weigh risk of bias, consistency or precision.
Systematic review / meta-analysis
0
Randomized controlled trial
1
1 verified · 0 unverified
Other clinical trial
0
Observational / case report
1
0 verified · 1 unverified
In vitro / animal
0
Other / unclassified
0
Verified: design read from PubMed for a DOI that resolves to the cited paper Unverified: taken from the study's recorded description
Clinical Studies
Efficacy and safety of flavocoxid, a novel therapeutic, compared with naproxen: a randomized multicenter controlled trial in subjects with osteoarthritis of the knee
220 adults with knee osteoarthritis were randomised to flavocoxid 500 mg twice daily or naproxen 500 mg twice daily for 12 weeks. Over 90% of subjects in both arms improved, with no statistically significant difference in efficacy in the intent-to-treat population; the flavocoxid arm had significantly fewer upper gastrointestinal and oedema-related adverse events. The tested agent is a fixed combination of an Acacia catechu extract standardised for catechins with a Scutellaria baicalensis extract standardised for baicalin, so this is not evidence for Acacia catechu alone, and the drug it tested was subsequently withdrawn from the US market over liver and lung toxicity.
Acute Liver Injury due to Flavocoxid (Limbrel), a Medical Food for Osteoarthritis: A Case Series
Among 877 patients enrolled prospectively by the US Drug-Induced Liver Injury Network, four cases of acute liver injury were attributed to flavocoxid, the Acacia catechu plus Scutellaria baicalensis product. All four were women aged 57 to 68 and all developed symptomatic liver injury one to three months after starting the product; all cases were self-limited after withdrawal, with no acute liver failure and no progression to chronic hepatitis. This is the primary safety evidence behind the FDA's 2017 warning and requested recall of the product.
Historical Texts
Ben Cao Gang Mu
Ming dynasty, 1596References
- Monika Kumari, Radha, Manoj Kumar, Baohong Zhang, Ryszard Amarowicz, Sunil Puri, Ashok Pundir, Sonia Rathour, Neeraj Kumari, Deepak Chandran, Abhijit Dey, Niharika Sharma, Sureshkumar Rajalingam, Pran Mohankumar, Surinder Sandhu, Nutan Pant, Raja Priya Ravichandran, Marimuthu Subramani, Kunjammal Pandi, Muthamilselvan Muthukumar, Gokhan Zengin, Mohamed Mekhemar, Jose M. Lorenzo. Acacia catechu (L.f.) Willd.: A Review on Bioactive Compounds and Their Health Promoting Functionalities . Plants (2022) [DOI]
- Rana N, Bala M, Kumar V, Yadav R, Jain N, Mathew D, Bisht K, Kumar R, Kumar S. A Systematic Review Exploring the Phytochemical Composition and Anticancer Activities of Acacia catechu . Medical Sciences (2025) [DOI]
This information is for educational purposes only and is not intended to replace professional medical advice. Always consult a qualified healthcare provider before using any herbal remedy, especially if you are pregnant, nursing, or taking medications.
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