Dan Fan
StarCuSO₄·5H₂O (Chalcanthite)
Traditionally used for
- Eye health
- Nose & throat
- Teeth & mouth
- Cough & breathing
- Digestion
- Skin
Cautions & contraindications
- Liver conditions
- Kidney conditions
- Toxic — professional use only
☯ TCM Properties
Induces Vomiting to Expel Phlegm; Resolves Toxicity; Dries dampness and draws out moisture; Removes Putridity and Promotes Tissue Regeneration
Traditional Chinese Uses
Dan Fan (copper sulfate crystals) is a toxic mineral substance used in Chinese medicine primarily as an emergency emetic to induce vomiting when thick Phlegm blocks the throat or when toxic substances have been ingested. It is also used externally as a wash for mouth sores, gum disease, eye inflammation, and skin ulcers. Because of its significant toxicity, it must only be administered by a qualified practitioner in carefully controlled, very small doses and for strictly indicated acute conditions.
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Botanical Description
Dan Fan is the traditional Chinese pharmacopoeial name for chalcanthite, a naturally occurring hydrated copper(II) sulfate mineral with the chemical formula CuSO4 5H2O. The crystals are typically a vivid azure to deep sky-blue, forming triclinic prismatic or tabular crystals, often occurring as crusts, stalactitic masses, or efflorescences in the oxidized zones of copper sulfide ore deposits. The mineral is brittle, water-soluble, and has a vitreous luster with a hardness of about 2.5 on the Mohs scale. On exposure to dry air it gradually loses water of crystallization and turns into a pale powdery anhydrous form. In medicinal use the crystals are powdered finely. Copper sulfate is acutely toxic if ingested in any significant quantity and modern internal use is strongly discouraged.
Active Constituents
Copper(II) sulfate pentahydrate
Sulfate mineral (chalcanthite)Concentration: Dominant phase; about 25.5% copper by mass
The whole of the drug's action and the whole of its danger. Cupric ion precipitates mucosal protein on contact, which produces both the reflex emesis the drug is prescribed for and the corrosive gastro-oesophageal injury that follows an overdose. Absorbed copper then drives oxidative injury to erythrocyte membranes and haemoglobin, giving intravascular haemolysis and methaemoglobinaemia, with hepatic and renal injury behind it.
Water of crystallisation
Structural (lattice) waterConcentration: 5 mol per mol CuSO4, about 36.1% by mass
Gives chalcanthite its blue colour. On efflorescence the crystals turn white or pale grey anhydrous CuSO4, which is roughly 1.6 times as strong per gram. Because the therapeutic emetic dose is a few hundred milligrams, this is not a trivial difference: a whitened, dried-out sample dosed by the same weight is a substantial overdose.
Iron, zinc and manganese sulfates
Isostructural accessory sulfate phasesConcentration: Variable; higher in unrefined mined material
Chalcanthite forms in the oxidised upper zones of copper sulfide ore bodies alongside melanterite (FeSO4·7H2O) and goslarite (ZnSO4·7H2O), which co-crystallise readily with it. Their presence dilutes the copper content unpredictably, so mined Dan Fan is not a defined strength.
Arsenic, antimony, lead, cadmium and selenium
Heavy metal and metalloid contaminantsConcentration: Ore-body dependent; potentially substantial in natural chalcanthite
The copper minerals chalcanthite weathers from routinely carry arsenic and antimony (from tennantite and tetrahedrite) and lead, cadmium and selenium from associated sulfides. Natural Dan Fan is therefore not simply impure copper sulfate; it can carry a second toxic metal load with no relationship to the copper assay.
Residual acidity
Free mineral acid and acid hydrolysis productsConcentration: Aqueous solutions are distinctly acidic
Copper sulfate solutions hydrolyse to give an acidic pH, and secondary sulfate minerals often carry adsorbed free sulfuric acid. This adds a straightforward chemical burn to the protein-precipitating action of the cupric ion and is part of why ingestion produces oesophagitis and gastritis rather than simple nausea.
⚠ Drug Interactions
Agricultural and technical grade copper sulfate (Bordeaux mixture, fungicide, algaecide, root killer)
Medicinal Dan Fan and the blue crystals sold as a fungicide are the same compound and look identical, but the agricultural product is unassayed, is packaged in kilogram quantities and often carries higher contaminant loads. Copper sulfate poisoning accounts for a large share of heavy metal poisoning admissions in South Asia, with reported mortality in the range of 14% to 36%, and the source is nearly always the agricultural or industrial grade. A fatal case is documented after ingestion of 30 g, with acute kidney injury, severe intravascular haemolysis and methaemoglobinaemia by the second day and death at 48 hours despite chelation and dialysis.
Clinical note: Never dispense Dan Fan from a bulk agricultural source, and never leave it in a domestic setting where the quantity available exceeds a therapeutic dose. Ingestion of more than about 1 g causes features of toxicity and amounts around 10 g have proved lethal; there is no safe margin to work with at kitchen-cupboard quantities.
Alumen (Bai Fan) and Melanteritum (Lu Fan, Zao Fan)
Dan Fan, Bai Fan (potash alum) and Lu Fan (melanterite, ferrous sulfate) are all called fan, are all hydrated sulfate crystals and are all used as astringent externals. Their toxicities are not comparable. Dan Fan is dosed internally in fractions of a gram as a deliberate emetic and poison, while alum is given at several times that weight. Dispensing Dan Fan where Bai Fan was intended converts an astringent prescription into a copper poisoning; the reverse leaves an intended emetic inert.
Clinical note: Check the colour before dispensing: Dan Fan is deep blue, Lu Fan pale green, Bai Fan colourless or white. Store Dan Fan separately from the other vitriols and label it as a toxic drug. Treat any bottle labelled only fan as unidentified.
Penicillamine, trientine and zinc salts (copper-lowering therapy in Wilson disease)
Wilson disease is a disorder of copper excretion; the entire treatment is directed at removing copper and blocking its absorption. Giving a copper salt to such a patient loads the exact metal the therapy is removing, into a liver and brain already at the limit of their capacity. The same chelators (penicillamine, EDTA, dimercaprol, sodium dimercaptopropane sulfonate) are what is used to treat acute copper sulfate poisoning, which underlines the point.
Clinical note: Dan Fan is absolutely contraindicated in Wilson disease and in any other state of copper overload or impaired biliary excretion, including cholestasis. Ask about liver disease before prescribing, and do not prescribe it at all where the history is uncertain.
Corrosive-ingestion protocols and other emetics or gastric lavage
Dan Fan is prescribed as an emetic, but the same cupric ion that triggers vomiting is corrosive to the mucosa it passes. Endoscopy after copper salt ingestion has documented diffuse oesophagitis and gastritis in a patient who had none of the classic haemolytic or metabolic laboratory abnormalities, so the absence of systemic signs does not exclude a chemical burn. Repeated induced vomiting brings the corrosive back across the injured oesophagus.
Clinical note: Do not use Dan Fan to induce vomiting after any corrosive or hydrocarbon ingestion, and do not repeat the emetic dose if the first fails. If more than a therapeutic dose has been taken, this is a toxicological emergency: refer for endoscopy and chelation rather than trying to empty the stomach with more of the drug.
Dapsone, primaquine, topical anaesthetics and other methaemoglobin-forming drugs
Copper oxidises haemoglobin iron to the ferric state, and methaemoglobinaemia is a recognised feature of copper sulfate poisoning alongside intravascular haemolysis. Any concurrent oxidant drug adds to that load, and the combination is worse than either alone because the haemolysis simultaneously removes the red cells available to carry oxygen.
Clinical note: Avoid Dan Fan entirely in patients on oxidant drugs, and in G6PD deficiency, where oxidative haemolysis is the expected response. Cyanosis with a normal arterial oxygen tension and chocolate-coloured blood after a Dan Fan dose is methaemoglobinaemia until proved otherwise.
Nephrotoxic drugs (aminoglycosides, NSAIDs, iodinated contrast, calcineurin inhibitors)
Acute kidney injury after copper sulfate ingestion arises both from direct tubular toxicity and from the pigment load of massive intravascular haemolysis, and rhabdomyolysis has been reported as an additional contributor. A kidney handling free haemoglobin and copper simultaneously has no reserve for a second insult.
Clinical note: Do not prescribe Dan Fan to anyone with existing renal impairment or on nephrotoxic therapy. If a poisoning occurs, expect renal failure and involve nephrology early; haemodialysis was required in the fatal case series reported.
Copper sulfate applied to broken skin, mucosa or wounds
Dan Fan's external indications are all applications to damaged surfaces: eroded cervix, aphthous ulcer, exuberant granulation tissue. Acute copper sulfate poisoning has been documented from dermal absorption in an occupational exposure, which establishes that the skin route is not safe by default; damaged epithelium removes the barrier that limits it further.
Clinical note: Limit external use to a small, defined area for a single short application, never to a large or extensively ulcerated surface, and never under an occlusive dressing. Reassess rather than repeat if the first application does not achieve the intended debridement.
Dosage
| Form | Amount | Frequency | Duration | Population | Notes |
|---|---|---|---|---|---|
| topical | Appropriate amount | — | — | — | No Chinese Pharmacopoeia 2025 monograph for this drug, so no pharmacopoeial dose is given here. Copper sulfate (CuSO₄·5H₂O), used externally to sores, and historically internally as a prompt emetic. **The internal emetic use is obsolete and hazardous** — copper sulfate causes haemolysis, hepatic and renal injury, and death has followed a few grams; no internal dose is given here. The stored value of 6-15 g as a decoction was filler and would have been fatal. The previous value was generic filler generated from tcm_category and has been removed rather than replaced with an estimate. |
⚠ Safety & Contraindications
- Liver conditions
- Kidney conditions
- Toxic — professional use only
Contraindications
Its use is prohibited in patients with weak constitution.
Source: Xi S, Gong Y. Essentials of Chinese Materia Medica and Medical Formulas. Academic Press/Elsevier, 2017, p. 399.
Historical Texts
Shen Nong Ben Cao Jing
Han dynasty, compiled c. 200 BCE to 200 CEBen Cao Gang Mu (Li Shizhen)
Ming dynasty, completed 1578, first printed 1596References
- Chuttani H.K.; Gupta P.S.; Gulati S.; Gupta D.N.. Acute copper sulfate poisoning . The American Journal of Medicine (1965) [DOI]
- Chandra Atanu; Ansar Mariam; Chatterjee Arkaketan; Chatterjee Rupak; Dasgupta Sugata. Fatal intravascular haemolysis due to copper sulfate poisoning: insights and literature review . BMJ Case Reports (2024) [DOI]
- Zhao Yingxin; Li Ruifang; Wang Chenguang; Li Chen; Wang Lijun. Successful treatment of acute oral copper sulfate poisoning: a case report . Frontiers in Pharmacology (2026) [DOI]
- Galust Henrik; Seltzer Justin A.; Hardin Jeremy R.; Friedman Nathan A.; Clark Richard F.. “Campfire corrosive: Isolated gastrointestinal injury following ingestion of copper salts” . The American Journal of Emergency Medicine (2023) [DOI]
- Park Kyung Sun; Kwon Jee Hyun; Park Sang Hyuk; Ha Won; Lee Jiho; An Hyun Chan; Kim Yangho. Acute copper sulfate poisoning resulting from dermal absorption . American Journal of Industrial Medicine (2018) [DOI]
- Oldenquist G. Parenteral copper sulfate poisoning causing acute renal failure . Nephrology Dialysis Transplantation (1999) [DOI]
- Li Ting; Lu Yuan-qiang. Residual hyperglycemia after successful treatment of a patient with severe copper sulfate poisoning . Journal of Zhejiang University-SCIENCE B (2024) [DOI]
- Dai Min; Wang Ding. Mineral medicines of the East: an analysis of records in historical Chinese and Japanese medical texts . Frontiers in Pharmacology (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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