Chi Shi Zhi
StarHalloysite (hydrated aluminum silicate mineral, Al₄(Si₄O₁₀)(OH)₈·4H₂O)
Traditionally used for
- 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; Promotes Tissue Regeneration and Heals Sores; Astringes to Stop Vaginal Discharge
Traditional Chinese Uses
Chi Shi Zhi (halloysite clay, red halloysite) is a warm, astringent mineral substance used to bind the intestines and stop chronic diarrhea, secure Jing and control abnormal vaginal discharge, and stop certain types of bleeding. It is especially indicated for chronic diarrhea or dysentery with blood that has not responded to other treatments. Its strong astringent properties make it effective for binding and consolidating the lower burner when deficiency-type leakage is the primary concern.
Relationships
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Botanical Description
Chi Shi Zhi is a naturally occurring hydrated aluminum silicate clay mineral, principally halloysite (Al2Si2O5(OH)4·2H2O) and related kaolin-group phyllosilicates, often colored red, pink, or yellowish by iron-oxide impurities. The material is mined from weathered volcanic or sedimentary deposits in China and elsewhere; the medicinal grade is selected for its bright reddish color, smooth waxy fracture, and tongue-sticking property typical of the kaolin clays. It is ground to a fine powder, washed (levigated) to remove gritty impurities, and calcined before use. In traditional Chinese medicine the prepared mineral is sweet, sour, astringent, and warm, binding the intestines to stop chronic diarrhea and dysentery, securing the lower jiao to stop uterine bleeding and excessive vaginal discharge, and applied externally to absorb damp exudates and promote healing of non-healing sores.
Active Constituents
Halloysite, 10 angstrom polyhydrous kaolinite
Phyllosilicate clay mineral (1:1 kaolin-group, hydrated interlayer)Concentration: The Chinese Pharmacopoeia 2020 defines the drug as this species with the formula Al4(Si4O10)(OH)8 4H2O but sets no content limit for it, so the formula is a species definition and not an assay specification. X-ray diffraction of 15 market batches found 10 angstrom halloysite as the dominant phase in the genuine material (Wang et al. 2024).
The hydrated interlayer distinguishes 10 angstrom halloysite from kaolinite and gives the mineral its rolled tubular habit and high water uptake; strong hygroscopicity is the property the classical materia medica was describing when it called good Chi Shi Zhi sticky to the tongue, and the 2024 study proposes hygroscopicity as the practical test that separates genuine material from substitutes.
Metahalloysite, 7 angstrom polyhydrous kaolinite
Phyllosilicate clay mineral (dehydrated halloysite, Al4(Si4O10)(OH)8)Concentration: Commonly present alongside the 10 angstrom phase in market batches (Wang et al. 2024). It is the dehydration product of 10 angstrom halloysite and is structurally close to kaolinite.
Because it is what halloysite becomes on losing interlayer water, its proportion rises with drying, ageing and heating, so calcined Chi Shi Zhi is a different mineral assemblage from the raw drug and can be expected to have lower water uptake.
Hematite and other iron oxide
Accessory iron oxide mineralConcentration: Trace, and the source of the red colour on which the drug identity depends. Bulk composition quoted for the drug in the 1975 Quan Guo Zhong Cao Yao Hui Bian is Al2O3 34.7 percent, SiO2 40.8 percent, water 24.5 percent, with trace oxides of iron, chromium and magnesium; that is a textbook bulk figure, not a modern assay of a defined batch.
Iron oxide is a colouring accessory rather than a therapeutic constituent at these levels; its practical importance is that the amount of it is what decides whether a given clay is sold as Chi Shi Zhi or as Bai Shi Zhi.
Dickite, nacrite, gibbsite and mica
Accessory kaolin-group and aluminous mineralsConcentration: Reported as the usual associated minerals of medicinal Chi Shi Zhi (Wang et al. 2024). In that study nacrite occurred with the halloysite in genuine batches, while dickite and mica appeared as the entire substance of several substituted batches.
These are the minerals that make the drug variable. The same associated phases that occur as minor accessories in genuine material also occur as whole-rock substitutes, so identification by appearance alone is unreliable and X-ray diffraction is the discriminating method.
Arsenic, lead, cadmium and chromium
Heavy metal and metalloid contaminants (not assayed in this drug)Concentration: No published multi-element assay of Chi Shi Zhi was located. For orientation only, the sister drug Bai Shi Zhi from the same kaolin-group deposits measured arsenic 4.16 to 29.63 mg/kg, lead 3.97 to 64.24 mg/kg, cadmium up to 16.45 mg/kg and chromium 1.85 to 34.92 mg/kg across 26 batches (Zhu et al. 2019). Those are figures for a different drug and must not be read as a Chi Shi Zhi assay.
Recorded as an explicit gap. The Chinese Pharmacopoeia monograph for Chi Shi Zhi carries no heavy-metal or arsenic limit test, and the pharmacopoeial ceilings for lead, cadmium, arsenic, mercury and copper are written for plant-derived materials, so nothing in routine quality control would detect a contaminated batch.
⚠ 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 Chi 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 Chi 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 Chi 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 Chi 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.
Dickite, muscovite and phengite sold as Chi Shi Zhi
X-ray diffraction of 15 batches bought in Shaanxi, Hebei, Henan, Anhui, Jiangxi, Shandong, Fujian and Shanxi identified only 10 as genuine halloysite. Two were phengite, two were dickite and one was muscovite, so a third of the commercial sample was a different mineral (Wang et al., Chinese Journal of Experimental Traditional Medical Formulae 2024). Micas and dickite do not share halloysite hygroscopicity or its tubular high-surface-area habit, so a substituted batch will neither bind fluid in the gut nor adsorb drugs the way the genuine material does.
Clinical note: Treat market-bought Chi Shi Zhi as unverified unless the supplier provides X-ray diffraction identification. Hygroscopicity is the practical bench discriminator proposed in that study: genuine material takes up markedly more water than the substitutes.
Rou Gui and Guan Gui (Cinnamomum cassia bark)
The classical shi jiu wei list of nineteen antagonisms pairs guan gui with shi zhi, making cassia bark and Chi Shi Zhi a named traditional incompatibility. No pharmacological or clinical study of the pair was located, and no mechanism has been demonstrated. It is recorded here because prescribers work from that list, not because there is evidence of harm.
Clinical note: Recognise the pairing as a traditional prohibition rather than a documented pharmacological interaction; some classical formulas deliberately break it. Do not present it to a patient as an established drug interaction.
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 |
|---|---|---|---|---|---|
| decoction (pre-decocted) | 9–12 g | Daily | — | — | 中国药典 2020 【用法与用量】9～12g，先煎。外用适量，研末敷患处。 【注意】不宜与肉桂同用。 【性味与归经】甘、酸、涩，温。归大肠、胃经。 — Chinese Pharmacopoeia 2020, quoted verbatim; route and cautions preserved. Replaces a cleared category-filler value. |
Dui Yao — Herb Pairs
The classical two-herb combinations this herb appears in, each with an action neither herb has alone.
Astringing the intestines combined with warming the middle, the pair treats chronic cold-type dysentery with pus and blood.
Traditionally with Jing Mi (non-glutinous rice). Not for damp-heat dysentery.
Core pair of a classical formula — Tao Hua Tang, Shang Han Lun (Zhang Zhongjing)
Two heavy, astringent minerals bind the lower burner together, stopping chronic, incontinent diarrhea that has not responded to regulating the middle.
Not for diarrhea with an unresolved pathogen or accumulation.
Core pair of a classical formula — Chi Shi Zhi Yu Yu Liang Tang, Shang Han Lun (Zhang Zhongjing)
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.
⚠ Rule-Based Cautions
These entries come from the deterministic rule tables that gate Verscienta's formula tools — classical pair prohibitions, pregnancy and lactation contraindications, and dose ceilings.
Incompatibilities (十八反 / 十九畏)
- 十九畏: Rou Gui × Chi Shi Zhi — avoid combining with Rou Gui / Guan Gui / Cinnamomi Cortex / Cinnamon bark
Historical Texts
Shen Nong Ben Cao Jing
Eastern Han, c. 200 CEShang Han Lun (Zhang Zhongjing)
Eastern Han, c. 200 CEJin Gui Yao Lue (Zhang Zhongjing)
Eastern Han, c. 200 CEBen Cao Jing Ji Zhu (Tao Hongjing)
Southern and Northern Dynasties, c. 500 CERi Hua Zi Ben Cao
Five Dynasties to early Song, 10th centuryBen Cao Tu Jing (Su Song)
Northern Song, 1061Ben Cao Gang Mu (Li Shizhen)
Ming, 1596References
- 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)
- 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)
- 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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