Ci Shi
StarFe₃O₄ (ferriferrous oxide, magnetite mineral of the spinel group)
Traditionally used for
- Dizziness
- Eye health
- Ears & hearing
- Mood & calm
- Heart & circulation
☯ TCM Properties
Anchors and Calms the Spirit; Calms the Liver and Subdues Yang; Opens the Ear Orifices and Brightens the Eyes; Aids the Kidneys in Grasping Qi; Benefits the Kidneys
Traditional Chinese Uses
Ci Shi (magnetite) is a cold, salty mineral substance used to anchor and calm overactive Liver Yang while simultaneously tonifying Kidney Yin. It is most applicable to Kidney Yin deficiency with Liver Yang rising, presenting as dizziness, tinnitus, blurred vision, and palpitations. It also calms the Spirit and is used for seizures and fright-induced restlessness. Its weight and anchoring nature make it a representative "heavy settling" mineral in TCM practice.
Relationships
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Botanical Description
Ci Shi is the medicinal form of magnetite, the ferrimagnetic iron oxide mineral with composition Fe3O4 (more precisely FeIIFeIII2O4, an inverse spinel). It occurs as black to brownish-black, opaque, metallic to submetallic octahedral crystals or massive granular aggregates with a Mohs hardness of 5.5–6.5 and a characteristic strong attraction to a magnet — a property already noted in early Chinese pharmacopoeias, from which the name “lodestone” derives. Medicinal-grade material is broken up, calcined red-hot, quenched repeatedly in vinegar to render it more friable, and ground to a fine powder. In traditional Chinese medicine the prepared mineral is acrid, salty, and cold, sedating the heart and anchoring the floating Yang for palpitations, insomnia, restlessness, and tremor, grasping the Qi to relieve wheezing of kidney-deficiency type, and improving hearing and vision for tinnitus, deafness, and blurred sight.
Active Constituents
Magnetite, Fe3O4
Mixed-valence iron oxide, inverse spinel structureConcentration: The Chinese Pharmacopoeia does not set a limit on Fe3O4 itself but on total iron: not less than 50.0 percent Fe for the raw drug and not less than 45.0 percent for the calcined drug, determined by dissolving in hydrochloric acid with fluoride, reducing with stannous chloride and titrating with potassium dichromate, each 1 mL of 0.01667 mol/L dichromate corresponding to 5.585 mg of Fe. Stoichiometric Fe3O4 is 72.4 percent Fe, so a monograph floor of 50 percent permits nearly a third of the material to be something other than magnetite.
Magnetite carries both Fe(II) and Fe(III) on octahedral sites, which is what makes it far more readily acid-soluble than a purely ferric oxide and is the likely basis of whatever systemic iron effect the drug has. It is also why the drug is ferrimagnetic in the raw state, the property the classical materia medica used to grade it, and why the calcined drug is described in the pharmacopoeia as no longer magnetic.
Hematite, Fe2O3
Accessory ferric oxide phaseConcentration: Present as a distinct phase in raw Magnetitum and reported to disappear after calcination, while Fe3O4 remains the main phase and crystallite size increases from 24.5 to 35.7 nm (Li et al., Frontiers of Chemistry in China 2007).
The disappearance of the ferric phase and the coarsening of the crystallites are direct evidence that calcination is a mineralogical change and not merely a cleaning step, so raw and calcined Ci Shi should be treated as two drugs.
Ferrous iron liberated by calcination and vinegar quenching
Processing-derived soluble iron speciesConcentration: Not expressed as an absolute figure in the sources located, but ferrous iron dissolution has been formally adopted, alongside iron mass fraction and surface colour, as a critical quality attribute of the calcination process, with an optimised procedure of 750 degrees Celsius for 1 hour, a 4 cm bed depth, 0.4 to 0.8 cm particle size and a single vinegar quench (Zeng et al., China Journal of Chinese Materia Medica 2025). The pharmacopoeial ratio is 30 kg of vinegar per 100 kg of Magnetitum.
This is the clearest case in the batch of processing being measurably designed to change solubility. Acetic acid quenching of red-hot magnetite fractures the grains and leaves acid-soluble ferrous species on the fresh surfaces, which is what makes the calcined drug the form used when a systemic effect is wanted, and what makes iron chelation interactions more likely with the calcined form than the raw.
Lead and cadmium
Heavy metal contaminantsConcentration: Present in raw Magnetitum and reported to be clearly reduced by calcination (Li et al. 2007). No absolute concentrations for either the raw or the calcined drug were located, and the Chinese Pharmacopoeia monograph carries no lead or cadmium limit test.
Calcination lowering the lead and cadmium burden is one of the few places where a traditional processing step has a demonstrated toxicological benefit, but with no numbers and no monograph limit it cannot be relied on to bring a given batch within any particular ceiling.
Arsenic
Metalloid contaminantConcentration: Not quantified in an accessible source. Arsenic solubility in boiling-water extracts of raw versus calcined Magnetitum was the specific subject of a 1995 study (Tie and Xing, Zhongguo Zhong Yao Za Zhi 20(5):278-280, 318), which is the correct question to ask because what matters clinically is the arsenic that comes out into a decoction rather than the arsenic in the rock. Magnetite is also a known sorbent for arsenate from water (Mamindy-Pajany et al. 2011), so arsenic enrichment of natural magnetite ore is geochemically expected.
Recorded with its uncertainty intact. The pharmacopoeial arsenic ceiling of 2 mg/kg applies to plant-derived materials and decoction pieces, not to this monograph, and no arsenic limit test exists for Ci Shi.
Non-iron gangue
Silicate and oxide mineral matterConcentration: Whatever makes up the balance of the drug below the 50.0 percent iron floor, which the monograph neither identifies nor limits.
Worth stating plainly because the assay is for total iron only: a batch can meet the pharmacopoeial specification while up to about a third of its mass is unidentified rock.
⚠ Drug Interactions
Levothyroxine
Iron binds thyroxine directly. In 14 patients with primary hypothyroidism on stable replacement who took 300 mg ferrous sulfate with their thyroxine daily for 12 weeks, mean serum TSH rose from 1.6 to 5.4 mU/L and nine of the 14 became more symptomatic; mixing iron and thyroxine in vitro produced a poorly soluble purple complex (Campbell et al., Annals of Internal Medicine 1992). That trial used soluble ferrous sulfate. Magnetite is a mixed-valence oxide and is more acid-soluble than a purely ferric ore, and the calcined vinegar-quenched form is more soluble still, but the dissolved iron dose delivered by a decoction has not been measured, so the direction of the interaction is established while its magnitude here is not.
Clinical note: Separate the mineral from levothyroxine by at least four hours. If a euthyroid patient is started on the mineral for more than a few weeks, recheck TSH.
Fluoroquinolone antibiotics
Fluoroquinolones chelate divalent and trivalent metal cations at the 3-carboxyl and 4-oxo positions, forming poorly absorbed complexes. In three two-period crossover trials of eight healthy volunteers each, ferrous sulfate equivalent to 100 mg elemental iron reduced the AUC of norfloxacin by 73 percent, ciprofloxacin by 57 percent and ofloxacin by 25 percent (Lehto, Kivisto and Neuvonen, British Journal of Clinical Pharmacology 1994); an earlier study found the same for ciprofloxacin (Polk et al. 1989). Magnetite is a mixed-valence oxide and is more acid-soluble than a purely ferric ore, and the calcined vinegar-quenched form is more soluble still, but the dissolved iron dose delivered by a decoction has not been measured, so the direction of the interaction is established while its magnitude here is not.
Clinical note: Do not co-administer. Separate by at least two hours before or six hours after the quinolone, and preferably suspend the mineral for the duration of the antibiotic course.
Tetracycline antibiotics
Tetracyclines form stable chelates with iron. Neuvonen and Turakka showed in man that a range of iron salts inhibits tetracycline absorption (European Journal of Clinical Pharmacology 1974), and the affinity of tetracycline for aluminium and iron hydrous oxide surfaces is well characterised. Magnetite is a mixed-valence oxide and is more acid-soluble than a purely ferric ore, and the calcined vinegar-quenched form is more soluble still, but the dissolved iron dose delivered by a decoction has not been measured, so the direction of the interaction is established while its magnitude here is not.
Clinical note: Separate by at least two hours, or suspend the mineral while the tetracycline course runs.
Levodopa
Levodopa is a catechol and chelates ferric iron strongly. In a randomised crossover trial in eight normal subjects, 325 mg ferrous sulfate taken with 250 mg levodopa reduced peak levodopa concentration by 55 percent and AUC by 51 percent; ferrous iron is oxidised rapidly to the ferric state in the presence of levodopa at small-intestinal pH, and it is the ferric complex that binds (Campbell and Hasinoff, Clinical Pharmacology and Therapeutics 1989). Magnetite is a mixed-valence oxide and is more acid-soluble than a purely ferric ore, and the calcined vinegar-quenched form is more soluble still, but the dissolved iron dose delivered by a decoction has not been measured, so the direction of the interaction is established while its magnitude here is not.
Clinical note: Separate by at least two hours in any patient on levodopa, and ask about new off-periods if the mineral has recently been added.
Oral iron supplements and iron-overload states
Ci Shi is an iron ore, and the traditional processing of these drugs by calcination and vinegar quenching is aimed precisely at raising the dissolved ferrous fraction. No study has measured how much iron a patient actually absorbs from a decoction of the drug, so the added load cannot be quantified, but it is not zero and it is additive to any prescribed iron.
Clinical note: Avoid in haemochromatosis, transfusion-dependent anaemia and other iron-overload states. Count the mineral as an unquantified iron source when reviewing a patient already on iron replacement.
Cinnabar (Zhu Sha, mercuric sulfide) in Ci Zhu Wan
The principal classical vehicle for Ci Shi is Ci Zhu Wan, originally Shen Qu Wan in Sun Simiao's Bei Ji Qian Jin Yao Fang, which combines magnetite with cinnabar and shen qu. Cinnabar is mercuric sulfide, and although its bioaccessibility is low relative to soluble mercury salts, mercury is measurably released from cinnabar-containing traditional preparations under simulated digestion (Lu et al., Journal of Trace Elements in Medicine and Biology 2017). Anyone prescribing Ci Shi in its classical formula is prescribing mercury, and cinnabar is restricted or prohibited in several jurisdictions.
Clinical note: Check the jurisdiction before dispensing any cinnabar-containing preparation, and check the actual formula rather than assuming a modern Ci Zhu Wan product is cinnabar-free. Where the indication is the magnetite, consider prescribing it without the cinnabar.
Antacids, proton pump inhibitors and H2 antagonists
Dissolution of an iron oxide depends on gastric acid, so acid suppression should reduce the already small soluble fraction released from magnetite. This has not been studied for the drug, and is recorded as a mechanistic expectation rather than an observation.
Clinical note: No action required for safety. Consider it if a patient on long-term acid suppression appears not to respond to an iron mineral.
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) | 9–30 g | Daily | — | — | 中国药典 2020 【用法与用量】9～30g，先煎。 【性味与归经】咸，寒。归肝、心、肾经。 — 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.
Two heavy minerals that together anchor the spirit and draw Heart fire down to the Kidney, calming palpitations and improving vision and hearing.
Palpitations, insomnia and tinnitus from Heart-Kidney disharmony (with Shen Qu to protect the stomach). Zhu Sha contains mercury; never heat it; short-term use only.
Core pair of a classical formula — Ci Zhu Wan (Shen Qu Wan), Bei Ji Qian Jin Yao Fang (Sun Simiao)
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
2 verified · 1 unverified
Other clinical trial
2
2 verified · 0 unverified
Observational / case report
0
In vitro / animal
3
0 verified · 3 unverified
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
The effect of ferrous sulphate on the absorption of norfloxacin, ciprofloxacin and ofloxacin.
Three separate two-period crossover trials, eight healthy volunteers each, single doses after an overnight fast. Ferrous sulfate corresponding to 100 mg elemental iron reduced the 0 to 24 hour AUC of norfloxacin by 73 percent, ciprofloxacin by 57 percent and ofloxacin by 25 percent, with matching falls in peak concentration and urinary recovery. The iron source was soluble ferrous sulfate, not a mineral iron oxide.
Effect of ferrous sulfate and multivitamins with zinc on absorption of ciprofloxacin in normal volunteers
Volunteer crossover study confirming that ferrous sulfate, and multivitamin preparations containing zinc, substantially reduce ciprofloxacin absorption. Establishes the interaction as a metal-cation chelation effect rather than something specific to one iron salt.
Inhibitory effect of various iron salts on the absorption of tetracycline in man
Human study comparing several iron salts for their effect on tetracycline absorption, finding inhibition across the range tested. It is the primary human evidence that the tetracycline-iron interaction is a property of iron rather than of one particular salt, which is what makes extrapolation to a mineral iron drug reasonable in direction if not in magnitude.
Ferrous Sulfate Reduces Thyroxine Efficacy in Patients with Hypothyroidism
Uncontrolled clinical trial in 14 patients with primary hypothyroidism on stable thyroxine, who took 300 mg ferrous sulfate with their thyroxine daily for 12 weeks. Mean TSH rose from 1.6 to 5.4 mU/L and nine of 14 developed more hypothyroid symptoms and signs, while the free thyroxine index did not change significantly. Mixing the two in vitro produced a poorly soluble purple iron-thyroxine complex.
Ferrous sulfate reduces levodopa bioavailability: Chelation as a possible mechanism
Randomised crossover trial in eight normal subjects. A 325 mg ferrous sulfate tablet taken with 250 mg levodopa reduced peak levodopa concentration by 55 percent and AUC by 51 percent. Ferrous iron oxidises rapidly to ferric in the presence of levodopa at small-intestinal pH, and the ferric complex binds strongly; the authors noted the clinical significance remained to be established.
Analytical comparison between unprepared and calcined magnetitum (Cishi)
Analytical comparison of raw and calcined Magnetitum. Fe3O4 remained the main phase after calcination while the Fe2O3 phase disappeared, crystallite size increased from 24.5 to 35.7 nm, and the contents of cadmium and lead were clearly reduced. This is a materials characterisation study, not a pharmacological or clinical one, but it is the direct evidence that the traditional processing step changes both the mineralogy and the contaminant load.
[Processing technology of calcined Magnetitum based on concept of QbD and its XRD characteristic spectra].
Quality-by-design optimisation of the calcination and vinegar quenching of Magnetitum. The critical process parameters were calcination temperature, calcination time, particle size, bed depth and number of vinegar quenches; the critical quality attributes were iron mass fraction, ferrous iron dissolution and surface colour. The optimised process was 750 degrees Celsius for 1 hour with a 4 cm bed depth, 0.4 to 0.8 cm particles and one vinegar quench, and X-ray diffraction characteristic spectra were established for the processed drug. Ferrous dissolution being chosen as a critical quality attribute is the explicit statement that this processing step exists to change solubility.
Effect of unprepared and calcined magnetitum of arsenic solubility in boiling water extracts
Compares the arsenic that dissolves into boiling-water extracts of raw and calcined Magnetitum. It asks the clinically correct question, since what reaches a patient is the arsenic extracted into a decoction rather than the arsenic in the rock. The full text is in Chinese and was not available for verification of the numerical results, so no figure is quoted here.
Historical Texts
Shen Nong Ben Cao Jing
Eastern Han, c. 200 CEBei Ji Qian Jin Yao Fang (Sun Simiao)
Tang, 652 CEBen Cao Jing Ji Zhu (Tao Hongjing)
Southern and Northern Dynasties, c. 500 CEBen Cao Tu Jing (Su Song)
Northern Song, 1061References
- Li Gang; Jin Tongshun; You Juan; Wang Lu; Wu Qinan. Analytical comparison between unprepared and calcined magnetitum (Cishi) . Frontiers of Chemistry in China (2007) [DOI]
- Lu Yuting; Yang Danyi; Song Xiaoni; Wang Sheng; Song Min; Hang Taijun. Bioaccessibility and health risk assessment of mercury in cinnabar containing Traditional Chinese Medicines . Journal of Trace Elements in Medicine and Biology (2017) [DOI]
- Mamindy-Pajany Y; Hurel C; Marmier N; Romeo M. Arsenic (V) adsorption from aqueous solution onto goethite, hematite, magnetite and zero-valent iron: Effects of pH, concentration and reversibility . Desalination (2011) [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]
- Xu Shan; Xu Liu; Xiang Tangyong; Zhu Ling; Gu Yi; Cai Baochang; Chen Zhipeng. Research Progress on Metallic Mineral Chinese Medicines . Journal of Nanjing University of Traditional Chinese Medicine (2021)
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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