Dries Dampness and stops discharge — diarrhea, dysentery, leucorrhea, and excessive sweating from Damp accumulation; astringent sulfate ions contract mucous membranes and reduce pathological secretions
Resolves toxicity and kills parasites — scabies, tinea, eczema, and dermatophyte infections; topical application creates strongly antiseptic, desiccating environment hostile to fungi and bacteria
Stops bleeding — hematemesis, hemoptysis, hematuria, and uterine bleeding from Heat forcing Blood out of vessels; astringent hemostatic action on bleeding mucous membranes
Transforms Phlegm and opens orifices — epilepsy, convulsions, and phlegm obstruction of the Heart orifices; classical pairing with Zhu Dan (pig bile) for phlegm-type epilepsy
Secondary Actions
Clears Damp-Heat from skin and mucous membranes — infected sores, mouth ulcers, sore throat (gargle solution), and trichomonas vaginitis; topical antifungal and antibacterial
External astringent for haemorrhoids — topical Bai Fan solution or Ku Fan (calcined alum) powder for haemorrhoid bleeding and prolapse
Classical emetic for poisoning — large oral dose induces vomiting; traditional antidote for food poisoning; now replaced by modern emetics
Classic Formulas
Bai Fan San (白矾散) — classical formula for Phlegm-type epilepsy; Bai Fan combined with Zhu Dan (pig bile) as pill; pungent dispersing of Phlegm obstruction in the Heart orifice; one of the earliest documented therapeutic uses of alum in TCM
Er Miao San variant (二妙散加白矾) — topical powder for Damp-Heat skin conditions: Bai Fan added to Huang Bai and Cang Zhu for weeping eczema and tinea with Damp-Heat; desiccates the lesion and clears Damp-Heat
Classical References
Shen Nong Ben Cao Jing: lists Fan Shi (矾石, alum stone) in the middle grade — 'sour, cold — clears Heat, dries Dampness, kills insects (parasites), stops the discharge of white matter; used externally for sores and internally for abdominal Heat-Damp patterns'
Ben Cao Gang Mu (Li Shizhen): 'Bai Fan (white alum) — sour, cold, astringent; purges Heat-Fire, dries Dampness, kills worms, stops bleeding; distinguishes four types of alum (white, yellow, black, green); Bai Fan is the principal medicinal form; Ku Fan (枯矾, calcined/roasted alum) has greater astringency after loss of crystalline water — the calcined form is preferred for external use in sores and hemorrhoids'
MINERAL NOTE: Bai Fan (白矾) is potassium aluminum sulfate dodecahydrate (KAl(SO₄)₂·12H₂O) — an inorganic mineral drug, not a plant herb. Ming Fan (明矾, herb #97) is the common market synonym for the same substance (Ming = 'clear/bright', referring to the transparent crystal); the XLSX source filed both names as separate entries. Ku Fan (枯矾) is the calcined form produced by heating to 100–200°C, removing crystalline water and increasing astringency; it is the preferred form for external use.
Modern Research
Active Compounds
Potassium aluminum sulfate dodecahydrate — KAl(SO₄)₂·12H₂O; Al³⁺ ions responsible for astringent, antiseptic, and protein-precipitating effects
Sulfate ion — desiccant and antibacterial activity; creates osmotically hostile environment for microorganisms
Aluminum ion (Al³⁺) — forms cross-links with protein carboxyl and hydroxyl groups → mucous membrane contraction, vasoconstriction, reduced secretion
Studied Effects
Antimicrobial and antifungal: alum solutions (1–5%) inhibit growth of dermatophytes (Trichophyton, Microsporum), Candida albicans, Staphylococcus aureus, and Escherichia coli through protein precipitation and pH reduction; validates traditional topical application for tinea, scabies, and infected wounds; minimum inhibitory concentrations for common dermatophytes fall within topical therapeutic range
Astringent and haemostatic: aluminum ions form insoluble protein-Al³⁺ complexes on mucosal surfaces, causing immediate vasoconstriction, reduced capillary permeability, and decreased glandular secretion; mechanism explains haemostatic, antidiarrheal, and anti-leucorrhea traditional indications; widely used in modern styptic pencils and alum block preparations
Antiperspirant mechanism: Al³⁺ ions plug eccrine sweat gland ducts (mechanical occlusion + protein precipitation of sweat duct cells); confirms the classical 'stops excessive sweating' TCM indication through a validated physical mechanism; alum was the original antiperspirant before modern aluminium chlorohydrate formulations
Safety & Interactions
Contraindications
Spleen-Stomach Deficiency Cold — cold, sour, astringent nature harms digestive Yang in deficiency patterns; loose stools, fatigue, and cold limbs contraindicate internal use
Yin Deficiency without Damp — astringent action traps pathogenic Qi if there is no Dampness to dry; use only when Damp or Phlegm is present
Cautions
Standard internal dose: 0.6–1.5 g in pill or powder form; NOT decocted (dissolves but bitter-astringent taste and aluminum bioavailability concerns); short-term use only
Long-term internal use caution: chronic aluminum ingestion is associated with neurological accumulation and bone mineralisation interference; do not use internally beyond 1–2 weeks at therapeutic doses
External use: 2–5% alum solution for topical applications is well-tolerated; Ku Fan (calcined alum) powder used neat for haemorrhoids, weeping eczema, and fungal infections — safe at standard external concentrations
Aluminium toxicity: relevant concern only with prolonged internal use at supratherapeutic doses; standard short-course TCM dosing does not present significant aluminium accumulation risk in patients with normal renal function; caution in chronic kidney disease