Traditionally used for
- Cough & breathing
- Bowel health
- Menstrual & women's health
- Skin
Cautions & contraindications
- Toxic — professional use only
☯ TCM Properties
Astringes the Intestines and Stops Diarrhea; Astringes and Stops Bleeding; Absorbs Dampness and Heals Sores; Tonifies Lung Qi; Dries Dampness in the Intestines
Traditional Chinese Uses
Bai Shi Zhi (kaolin or white halloysite clay) is a warm, astringent mineral substance used to stop chronic diarrhea, restrain excessive vaginal discharge, and stop bleeding from the lower body. Similar to Chi Shi Zhi (red halloysite), it works by consolidating and astringent the lower burner for deficiency-type leakage patterns. Its warm nature makes it especially appropriate when the underlying condition involves cold deficiency of the Spleen and Kidney.
Relationships
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Botanical Description
Bai Shi Zhi is kaolinite, a hydrated aluminium silicate clay mineral of idealised composition Al2Si2O5(OH)4, occurring as fine-grained, soft, earthy white to greyish-white masses formed by the weathering of feldspar-rich rocks such as granite. The medicinal grade is collected from kaolin clay deposits in southern and eastern China, then washed, levigated to remove sand and iron impurities, dried and reduced to a uniform powder. The finished mineral is dull white, sometimes faintly pink or yellow, very soft (Mohs about 2), opaque, with an earthy fracture and a smooth, slightly greasy feel; it adheres lightly to the tongue, has no odour and a mild, faintly clay-like taste. It is insoluble in water but disperses to form a smooth suspension, and is chemically inert to dilute acids and alkalis at room temperature.
Active Constituents
Kaolin-group hydrous aluminium silicate
Phyllosilicate clay mineral (1:1 dioctahedral layer silicate)Concentration: The composition quoted for this drug in the Chinese literature is SiO2 46.5 percent, Al2O3 39.5 percent, water 14.0 percent. Those are the stoichiometric proportions of ideal kaolinite Al2Si2O5(OH)4 to within a rounding error, so the published figure is a mineral-species ideal restated rather than an assay of medicinal material. Chinese pharmacognosy identifies the drug as polyhydrous kaolinite, that is halloysite (Halloysitum album), rather than kaolinite sensu stricto, so the binomial and the trade identity do not fully agree.
The 1:1 aluminosilicate layer presents a large hydrated surface with pH-dependent edge charge. That surface is the basis of both the traditional astringent and drying action and of the drug-binding problem: what takes up water, bile acids and bacterial toxins in the lumen also takes up co-administered drug molecules.
Aluminium
Major structural element (ICP-MS assay of medicinal material)Concentration: 11 012 to 123 220 mg/kg across 26 commercial batches from nine Chinese provinces, and the most abundant element measured (Zhu et al., China Pharmacy 2019).
Aluminium locked in an intact clay lattice is poorly bioavailable, but the eleven-fold spread between batches is a direct measure of how variable the mineral purity of market material is.
Iron
Accessory transition metal (ICP-MS assay)Concentration: 357 to 15 205 mg/kg across the same 26 batches.
Accessory iron oxide produces the pink, red and brown streaking recorded in most nominally white batches, and the forty-fold spread shows that Bai Shi Zhi and Chi Shi Zhi grade into one another in the marketplace rather than being cleanly separated colours.
Arsenic
Metalloid contaminantConcentration: 4.16 to 29.63 mg/kg. All 26 batches exceeded the 2 mg/kg ceiling that the Chinese Pharmacopoeia applies to plant-derived materials (Zhu et al. 2019).
This is the single most safety-relevant number published for the drug. No arsenic limit test exists for Bai Shi Zhi in any pharmacopoeia or provincial standard, so nothing in routine quality control would detect it.
Lead
Heavy metal contaminantConcentration: 3.97 to 64.24 mg/kg; 25 of 26 batches above the 5 mg/kg plant-material ceiling (Zhu et al. 2019).
Lead is inherited from the weathering-crust clay deposits the drug is dug from, and is not removed by the ordinary cleaning and grinding the drug receives.
Cadmium
Heavy metal contaminantConcentration: Mostly below 0.3 mg/kg, but three of 26 batches measured 1.24, 2.71 and 16.45 mg/kg (Zhu et al. 2019).
Usually low and occasionally extreme, which is the characteristic contaminant pattern of a dug mineral. A typical value protects nobody here; only batch testing does.
Chromium
Heavy metal contaminantConcentration: 1.85 to 34.92 mg/kg; 25 of 26 batches above the 2 mg/kg reference limit (Zhu et al. 2019).
Speciation was not determined, so the fraction present as chromium(VI) rather than the far less toxic chromium(III) is unknown for this drug.
Copper
Trace metalConcentration: Up to 98.29 mg/kg; 10 of 26 batches above the 20 mg/kg reference limit (Zhu et al. 2019).
Relevant mainly as a further index of ore impurity rather than as a toxicity concern at customary doses.
Mercury
Heavy metal contaminant (not assayed)Concentration: Not measured. Mercury was not among the 27 elements in the only published multi-element survey of this drug, so no mercury figure for Bai Shi Zhi exists in the accessible literature.
Recorded as an explicit gap. Absence of an assay is not evidence of absence, and no pharmacopoeial mercury limit applies to this drug.
⚠ Drug Interactions
Digoxin
Kaolin-group clay adsorbs digoxin in the gut lumen. In a Latin-square single-dose study in 10 volunteers, cumulative six-day urinary recovery of a 0.75 mg digoxin dose fell from 40.1 percent (control) to 23.4 percent with kaolin-pectin. A crossover study of dose separation found that co-administration cut the amount absorbed by 62 percent and more than doubled between-subject variability; kaolin-pectin given two hours before digoxin still reduced the extent of absorption by about 20 percent, while giving it two hours after had no measurable effect. Both studies used pharmaceutical kaolin-pectin suspension, not Bai Shi Zhi, so this is an extrapolation from the mineral class rather than a direct measurement of the Chinese drug.
Clinical note: Do not co-administer. Separate by at least two hours and give the clay after the digoxin, not before. Check digoxin levels when the mineral is started or stopped.
Phenytoin
In an everted rat intestine model, light kaolin reduced phenytoin absorption by 60.2 percent (McElnay, D'Arcy and Throne, International Journal of Pharmaceutics 1980); calcium citrate in the same model reduced it by 77.2 percent. The proposed mechanism is a physical coating barrier plus surface adsorption of a poorly soluble drug. This is a preclinical tissue model with pharmaceutical kaolin, not a human study and not Bai Shi Zhi.
Clinical note: Avoid concurrent dosing in any patient on phenytoin; separate by at least two hours and check plasma levels if the mineral is used for more than a few days.
Chloroquine
The chloroquine-kaolin absorption interaction was characterised using a buccal partitioning model (McElnay, Sidahmed and D'Arcy, Journal of Clinical Pharmacy and Therapeutics 1982). Chloroquine is a dibasic amine that is strongly cationic at gut pH and binds readily to the negatively charged clay surface. Pharmaceutical kaolin was the adsorbent studied.
Clinical note: Separate clay and chloroquine by at least two hours; this matters most where chloroquine is being used for treatment rather than intermittent prophylaxis.
Propranolol
Kaolin was among the agents shown to reduce propranolol absorption by McElnay, D'Arcy and Leonard (Experientia 1982). Propranolol is a lipophilic base that adsorbs to clay surfaces. Preclinical and pharmaceutical-kaolin evidence, not a study of Bai Shi Zhi.
Clinical note: Separate doses by at least two hours; watch for loss of rate control if a patient takes the mineral repeatedly through the day.
Tetracyclines and other adsorbable oral antibacterials
Light kaolin adsorbed a series of antibacterial substances in vitro (Fulayyeh and colleagues, Journal of Pharmacy and Pharmacology 1981). No human study pairs Bai Shi Zhi with any antibiotic, so the magnitude in a patient is unknown.
Clinical note: Separate from oral antibiotics by at least two hours, and prefer to suspend the mineral for the duration of a short antibiotic course.
Aspirin
In 10 fasting volunteers given 975 mg of aspirin, mean 48-hour urinary salicylate recovery was 98.6 percent with water and 90.6, 94.6 and 95.3 percent with 30, 60 and 90 mL of kaolin-pectin; the 30 and 60 mL treatments differed significantly from water, and absorption was not delayed. Activated charcoal in the same study gave 69.5 percent, showing that clay is a far weaker adsorbent than charcoal.
Clinical note: No action needed for occasional analgesic use. The same study concluded kaolin-pectin is not an adequate treatment for aspirin poisoning, so do not substitute the clay for activated charcoal in overdose.
Orally administered drugs in general
Adsorption onto the clay surface is a physical and largely non-selective process, and its extent varies with the ionisation of the drug and with the electrolyte content and dielectric constant of the luminal fluid (Armstrong and Clarke, Journal of Pharmaceutical Sciences 1973). That variability is why a single in vitro figure cannot be read as a clinical effect size, and why the interaction should be assumed for drugs that have never been studied with clay.
Clinical note: Separate the clay from every other oral medicine by at least two hours, and give the clay after the other drug where the schedule allows; in the digoxin work, dosing the clay two hours after the glycoside abolished the effect while dosing it two hours before did not.
Chelation therapy and heavy-metal exposure workup
Mineral drugs are dug ores, and the Chinese Pharmacopoeia limits for lead, cadmium, arsenic, mercury and copper are written for plant-derived materials and decoction pieces, not for the mineral monographs. A patient taking one of these minerals long term is therefore on an uncharacterised source of arsenic and lead, which will confuse the interpretation of a blood lead, a urine arsenic or a response to chelation.
Clinical note: If a patient on a mineral drug has an unexplained raised blood lead or urinary arsenic, treat the herb itself as a candidate source and have the actual batch assayed rather than assuming an occupational or dietary cause.
Dosage
| Form | Amount | Frequency | Duration | Population | Notes |
|---|---|---|---|---|---|
| topical | Appropriate amount — external use mainly | Daily | — | — | No ChP 一部 monograph (compare 赤石脂, which is in ChP). Kaolinite. Used chiefly externally as an absorbent and astringent powder for sores and weeping lesions. No pharmacopoeial internal dose is established here. |
Evidence Tier
Strong evidence · 8 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
3
0 verified · 3 unverified
Other clinical trial
0
Observational / case report
0
In vitro / animal
5
1 verified · 4 unverified
Show 5 studies
- Effect of antacid constituents, kaolin and calcium citrate on phenytoin absorption
- EXAMINATION OF THE CHLOROQUINE-KAOLIN DRUG ABSORPTION INTERACTION USING THE BUCCAL PARTITIONING MODEL
- The effect of activated dimethicone, other antacid constituents, and kaolin on the absorption of propranolol
- Adsorption of Antibacterial Substances on Attapulgite and Light Kaolin
- Influence of Solution Electrolyte Content and Dielectric Constant on Drug Adsorption by Kaolin
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
Decreased Bioavailability of Digoxin Due to Antacids and Kaolin-Pectin
Latin-square single-dose crossover in 10 normal volunteers. Cumulative six-day urinary recovery of a 0.75 mg digoxin dose was 40.1 percent under control and 23.4 percent with kaolin-pectin, with aluminium hydroxide, magnesium hydroxide and magnesium trisilicate intermediate; every treatment differed significantly from control. The investigators attributed the fall to reduced absorption rather than to altered gut transit. The material was pharmaceutical kaolin-pectin suspension, not a Chinese medicinal clay.
Influence of Kaolin–Pectin Suspension on Digoxin Bioavailability
Crossover study of dose separation in volunteers. Given together, kaolin-pectin delayed digoxin absorption, reduced the amount absorbed by 62 percent and more than doubled between-subject variability. Given two hours before digoxin it still reduced the extent of absorption by about 20 percent; given two hours after, neither rate nor extent was affected. This asymmetry is the evidential basis for dosing a clay after rather than before a critical drug.
Comparison of kaolin-pectin and activated charcoal for inhibition of aspirin absorption
Five-way crossover in 10 fasting volunteers taking three 325 mg aspirin tablets. Mean 48-hour urinary salicylate recovery was 98.6 percent with water, 90.6 to 95.3 percent across three kaolin-pectin volumes and 69.5 percent with 10 g activated charcoal. Kaolin-pectin reduced aspirin absorption significantly but modestly and did not delay it, and was judged inadequate for treating aspirin poisoning.
Effect of antacid constituents, kaolin and calcium citrate on phenytoin absorption
Everted rat intestine model. Light kaolin reduced phenytoin absorption by 60.2 percent and calcium citrate by 77.2 percent, both significant. The authors proposed that a kaolin coating of the mucosa acts as a physical barrier to absorption in addition to adsorbing drug in solution. Preclinical tissue model with pharmaceutical kaolin.
EXAMINATION OF THE CHLOROQUINE-KAOLIN DRUG ABSORPTION INTERACTION USING THE BUCCAL PARTITIONING MODEL
Uses the buccal partitioning model to characterise the interaction between chloroquine and kaolin, confirming that clay reduces the fraction of chloroquine available for absorption. A partitioning model rather than a systemic pharmacokinetic study, so it establishes the mechanism but not the clinical effect size.
The effect of activated dimethicone, other antacid constituents, and kaolin on the absorption of propranolol
Screens antacid constituents and kaolin for effects on propranolol absorption, placing kaolin among the agents that reduce it. Preclinical; the clay tested was pharmaceutical kaolin.
Adsorption of Antibacterial Substances on Attapulgite and Light Kaolin
In vitro adsorption of a range of antibacterial substances onto light kaolin and attapulgite, establishing that medicinal clays take up antibacterial drug molecules from solution. No clinical endpoint and no Chinese medicinal material was used.
Influence of Solution Electrolyte Content and Dielectric Constant on Drug Adsorption by Kaolin
Shows that how much drug kaolin adsorbs depends on the electrolyte content and dielectric constant of the surrounding solution. The practical consequence is that the size of a clay-drug interaction differs between gastric and intestinal conditions and between a fasted and a fed patient.
Historical Texts
Shen Nong Ben Cao Jing
Eastern Han, c. 200 CEBen Cao Jing Ji Zhu (Tao Hongjing)
Southern and Northern Dynasties, c. 500 CEGansu Provincial Standard for Chinese Medicinal Materials
2009 editionReferences
- Zhu Renyuan; Ji Liangliang; Zhang Xiaoping; Qiu Guoyu; Ma Xiao. Simultaneous Determination of 27 Kinds of Heavy Metals and Trace Elements in Halloysitum album by ICP-MS . China Pharmacy (2019)
- Wang Xiaofei; Wang Youshao; Chen Daihong; Sun Shuyuan; Cao Yan; Zheng Guohua; Li Juan. Herbal Textual Research, Quality Evaluation and Phase Analysis of Halloysitum Rubrum . Chinese Journal of Experimental Traditional Medical Formulae (2024)
- Carretero MI. Clay minerals and their beneficial effects upon human health. A review . Applied Clay Science (2002) [DOI]
- Young SL; Miller JD. Medicine Beneath Your Feet: A Biocultural Examination of the Risks and Benefits of Geophagy . Clays and Clay Minerals (2019) [DOI]
- Brindley GW; Goodyear J. X-ray studies of halloysite and metahalloysite . Mineralogical Magazine and Journal of the Mineralogical Society (1948) [DOI]
- Salgado-Campos VMJ; Bertolino LC; Silva FJ da; Mendes JC. Mineralogical characterization of clay mineral assemblages from Rio de Janeiro pegmatites to identify kaolinite and/or halloysite deposits . Ceramica (2020) [DOI]
- Han X; Luo JY; Liu QT; Li YJ; Xie YJ; Yang SH; Yang MH. Study on species and valence state of heavy metals and deleterious elements of mineral medicine . China Journal of Chinese Materia Medica (2015) [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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