Natural Herb Library

Alum

Chinese
白矾
Pinyin
Bai Fan
Latin
Alumen
Scientific specimen plate of Alum, Alumen, showing raw crystals, crystal habit, translucent fragments, powder form, calcined form, and diagnostic material details.
Botanical plate by Kodi . View print →

Known in TCM as Bai Fan (白矾), this sour and astringent, cold herb enters the Lung, Spleen, Large Intestine, and Liver. Traditionally, it dries Dampness and stops discharge, most often applied for dysentery, eczema, and uterine bleeding. Modern research has identified Potassium aluminum sulfate dodecahydrate among its active constituents.

Part used: Alum

TCM Properties

Taste
sour, astringent
Temperature
cold
Channels
Lung, Spleen, Large Intestine, Liver

Traditional Use

Primary Actions

  • 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

Conditions

Frequently Asked Questions

What is Alum used for?

Alum is traditionally used to 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. Research has investigated its effects on: 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.

Is Alum safe during pregnancy?

The safety of Alum during pregnancy has not been established. Consult a qualified healthcare provider before use.

What are the contraindications for Alum?

Alum should not be used in: 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. Consult a qualified practitioner before use.