Fu Hai Shi
StarCostazia aculeata Canu et Bassler / Pumice (volcanic rock)
Traditionally used for
- Cough & breathing
- Urinary & fluids
☯ TCM Properties
Clears Lung Heat and Transforms Phlegm; Dissipates Nodules and Softens Hardness; Promotes Urination and Relieves Stranguria
Traditional Chinese Uses
Fu Hai Shi (pumice stone) is a salty, cold mineral substance used primarily to dissolve stubborn, heat-type Phlegm — the thick, congealed kind lodged in the Lungs or forming hard nodules. It softens hardened masses from Phlegm accumulation, drains urinary stones from heat buildup in the Bladder, and relieves Lung Heat with difficult-to-expectorate phlegm. Its softening, dissolving properties make it applicable to diverse conditions involving hardened accumulations.
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Botanical Description
Fu Hai Shi (literally 'floating sea stone') refers to two distinct but interchangeably used substances in traditional Chinese medicine: the calcareous skeleton of marine bryozoan colonies (principally Costazia aculeata Canu et Bassler) collected from coastal waters of East Asia, or volcanic pumice — a porous, glassy igneous rock formed when frothy lava cools rapidly. Both materials share the defining characteristic of being light, porous, and capable of floating in water; the bryozoan form is composed largely of calcium carbonate, while pumice is a silicate volcanic glass. The substance is collected, washed clean of salt and impurities, dried, and crushed before use. In traditional Chinese medicine, Fu Hai Shi is salty, cold, and enters the lung and kidney channels; it clears heat, transforms phlegm, softens hardness, dissipates nodules, and promotes urination, used for stubborn cough with thick yellow phlegm, scrofula, and urinary stones. It is one of the classical mineral/animal phlegm-transforming substances.
Active Constituents
Calcium carbonate
Carbonate mineral (calcite)Concentration: 85 to 96 percent of the bryozoan-skeleton form, as reported in the Chinese materia medica literature for shi hua, the Costazia material; the pumice form contains essentially none
This is the whole of the calcareous drug's pharmacology. In gastric acid it dissolves to calcium ions and carbon dioxide, giving an antacid effect and a calcium load, and it is the reason every calcium-mediated drug interaction below applies. Which of the two accepted source materials was dispensed decides whether this constituent is present at all: this is not a trace difference between grades, it is the difference between a carbonate and a silicate.
Magnesium substituted into the calcite lattice
Carbonate mineral component (magnesian calcite)Concentration: Variable; bryozoan skeletal calcite spans low- to high-magnesium compositions and the proportion is set largely by biological control rather than by seawater temperature or salinity
Magnesium content governs how readily the skeleton dissolves, higher-magnesium calcite being the more soluble and the more vulnerable to acidification. For a drug that works by dissolving in gastric acid, the magnesium content of the particular colonies collected is therefore a real source of batch-to-batch variability, and it is not controlled for.
Aragonite
Carbonate mineral polymorphConcentration: Present in bimineralic and aragonitic bryozoan skeletons; calcitic forms predominate but bimineralic and aragonitic species occur alongside them
The second calcium carbonate polymorph. Which polymorph a bryozoan deposits is under strong biological control, so a collection of mixed colonies is mineralogically heterogeneous. Aragonite is the more soluble polymorph, which again bears on dissolution in the stomach.
Amorphous aluminosilicate volcanic glass
Silicate mineraloid (volcanic glass)Concentration: The bulk of the pumice-sourced form, which is described in the materia medica as silicates of aluminium, potassium and sodium with silicon dioxide as the principal component, similar in composition to glass
The pumice form is chemically inert and essentially insoluble in the gut. It provides no calcium, does not neutralise acid, and does not chelate. Its traditional action is attributed to its texture and its lightness rather than to anything it releases.
Chloride and magnesium salts of marine origin
Inorganic saltsConcentration: Present as adherent residues in material collected from the sea, in both the pumice and the skeletal form
Seawater residues carried on the drug. They are pharmacologically trivial but they are the reason marine-collected material is washed before use, and they mark the material as sea-collected rather than quarried.
Cadmium, lead, arsenic and mercury as contaminants
Heavy metal and metalloid contaminantsConcentration: Not established for this drug: it is not among the 11 marine drugs carried in the 2020 Chinese Pharmacopoeia, so it has no pharmacopoeial heavy metal limit of its own
This is the contaminant question that matters for a marine skeletal drug. Animal-derived Chinese medicines show the highest exceedance rates for lead, arsenic, cadmium and mercury of any category, and marine animal medicines are the worst within that group — oyster shell has been recorded at 18.18 mg/kg lead against a 5.0 mg/kg limit, and the cadmium limit applied to clam, oyster and pearl is only 0.3 mg/kg. Arsenic speciation matters as much as total arsenic, since arsenite is roughly 60 times more toxic than arsenate and arsenate about 70 times more toxic than the methylated forms, while marine organisms carry much of their arsenic as non-toxic arsenobetaine. No published survey covers this drug specifically, and absence of an assay is not evidence of absence.
⚠ Drug Interactions
Fu Shi (pumice) dispensed as Fu Hai Shi, or Costazia skeleton dispensed as Fu Shi
Fu Hai Shi has two officially recognised origins that are treated as interchangeable in practice: the calcareous skeleton of colonial bryozoans of the family Bao Kong Ke, chiefly the material called shi hua from Costazia aculeata and Costazia costazii, and the igneous rock pumice. The first is 85 to 96 percent calcium carbonate; the second is silicon-dioxide-dominated aluminosilicate glass. They share a name, a floating habit and an indication, and nothing else. Every calcium-mediated interaction listed below applies to the skeletal material and to none of the pumice material, and the antacid effect likewise. A prescription filled with the wrong one is not a potency variation, it is a different substance.
The taxonomy of the animal source is not settled and should not be presented as though it were. The World Register of Marine Species treats the genus Costazia Neviani, 1895 as not accepted and as a synonym of Celleporina Gray, 1848, and the specific combination Costazia aculeata Canu et Bassler as printed in the Chinese pharmacopoeial literature does not resolve to an accepted record there. This corpus's own genus-to-family table already carries Costazia as unmapped on the grounds that family placement differs between sources. The practical consequence is that the animal source cannot be authenticated to an accepted binomial, only to the trade description of the skeletal material.
Clinical note: Ask the dispensary which material was supplied before relying on any of the calcium interactions below, and record it. The two are distinguishable on inspection: the skeletal form is greyish-white to yellowish, coral-like, with forked branches and a networked structure; pumice is a grey vesicular volcanic rock. If the source cannot be established, manage the patient as though calcium carbonate were present, which is the more interaction-prone assumption.
Hai Fu Shi listed separately in the same prescription
Fu Hai Shi and Hai Fu Shi are the same drug, not two drugs that happen to share a source. The materia medica records fu hai shi as an alternative name for hai fu shi, entering the literature under that name in Yu Qiu Yao Jie in 1754, and both names cover the same two accepted source materials — the bryozoan skeleton and pumice — with the same indication, the same salty and cold nature, and the same Lung and Kidney channel entry. A catalogue or formula that carries both as separate entries will let a practitioner prescribe the same mineral twice.
Clinical note: Treat Fu Hai Shi, Hai Fu Shi and the plain Fu Shi entries as one drug when totalling a prescription. Where a reference database holds them as separate records, cross-reference them rather than dosing them independently.
Levothyroxine
Applies to the calcareous (Costazia) form. Thyroxine adsorbs onto calcium carbonate, and in a prospective study of 20 hypothyroid patients taking 1200 mg/day of elemental calcium as calcium carbonate together with their levothyroxine, mean free and total T4 fell significantly and mean thyrotropin rose from 1.6 to 2.7 mIU/L, reversing when the calcium was stopped. A carbonate-based herbal mineral taken in the same dosing window does the same thing.
Clinical note: Separate the herb from levothyroxine by at least four hours. If the herb is taken long term, recheck thyrotropin six to eight weeks after starting and again after stopping, because the dose may have been retitrated against the interaction.
Fluoroquinolone and tetracycline antibiotics (ciprofloxacin, levofloxacin, doxycycline)
Applies to the calcareous (Costazia) form. Divalent calcium chelates the 4-oxo and 3-carboxyl groups of fluoroquinolones and the equivalent sites on tetracyclines, forming poorly absorbed complexes. Calcium carbonate antacid has been shown in a crossover bioavailability study to reduce ciprofloxacin absorption. Because the effect is on absorption, the antibiotic simply never reaches therapeutic concentrations, which is a treatment failure rather than a toxicity.
Clinical note: Do not give in the same dosing window. Take the antibiotic at least two hours before or six hours after the herb, or suspend the herb for the antibiotic course, which is simpler and safer.
Oral bisphosphonates (alendronate, risedronate) and oral iron salts
Applies to the calcareous (Costazia) form. Oral bisphosphonates already have very low bioavailability and any divalent cation in the gut lumen abolishes what remains; their labelling requires dosing on an empty stomach away from all calcium. Calcium carbonate also depresses iron bioavailability by competing for divalent metal uptake in the duodenum.
Clinical note: Bisphosphonates must be taken on waking with water alone and nothing else for at least 30 minutes; do not put the herb in that window. Give oral iron at least two hours apart from the herb, and recheck ferritin if a patient on iron replacement plateaus after starting it.
Historical Texts
Ben Cao Shi Yi (Supplement to the Materia Medica), Chen Cangqi
Tang dynasty, 739Ri Hua Zi Ben Cao (Ri Hua-zi's Materia Medica)
Five Dynasties to early Song, c. 10th centuryBen Cao Yan Yi (Augmented Materia Medica), Kou Zongshi
Northern Song, 1116Ben Cao Gang Mu (Compendium of Materia Medica), Li Shizhen
Ming dynasty, 1596Yu Qiu Yao Jie (Yu Qiu's Explanation of Medicinals), Huang Yuanyu
Qing dynasty, 1754Received cautions of the materia medica tradition, transmitted through the standard Chinese drug compendia
Song through Qing, c. 10th-19th centuryReferences
- Guo, Yuan-sheng; Zuo, Tian-tian; Chen, An-zhen; Wang, Zhao; Jin, Hong-yu; Wei, Feng; Li, Ping; Ma, Shuang-cheng. Progress in quality control, detection techniques, speciation and risk assessment of heavy metals in marine traditional Chinese medicine . Chinese Medicine (2023) [DOI]
- Krzemińska, Małgorzata; Piwoni-Piórewicz, Anna; Boonzaaier-Davids, Melissa K.; Florence, Wayne; Waeschenbach, Andrea; Najorka, Jens; Jenkins, Helen L.; Kukliński, Piotr. Carbonate mineralogy and geochemistry of bryozoans along the South African coast . Marine Biology (2024) [DOI]
- Saulsbury, James G.; Piwoni-Piórewicz, Anna; Kukliński, Piotr; Di Martino, Emanuela; Liow, Lee Hsiang. Evolution of skeletal mineralogy in cheilostome bryozoans from calcite to aragonite seas . Geology (2025) [DOI]
- Taylor, Paul D.; Tan Shau-Hwai, Aileen; Kudryavstev, Anatoliy B.; Schopf, J. William. Carbonate mineralogy of a tropical bryozoan biota and its vulnerability to ocean acidification . Marine Biology Research (2016) [DOI]
- Singh, Nalini; Singh, Pramil N.; Hershman, Jerome M.. Effect of Calcium Carbonate on the Absorption of Levothyroxine . JAMA (2000) [DOI]
- Frost, R W; Lasseter, K C; Noe, A J; Shamblen, E C; Lettieri, J T. Effects of aluminum hydroxide and calcium carbonate antacids on the bioavailability of ciprofloxacin . Antimicrobial Agents and Chemotherapy (1992) [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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