☯ TCM Properties
Clears Lung Heat, transforms Phlegm and descends Lung Qi; Softens hardness and dissipates nodules; Promotes urination and expels Dampness; Controls acidity and stops pain (calcined and powdered)
Traditional Chinese Uses
Hai Ge Ke is the shell of marine clams (Meretrix meretrix and Cyclina sinensis, family Veneridae), a bitter, salty, cold substance entering the Lung, Stomach, and Kidney channels and grouped with the Phlegm-transforming medicinals. It clears Lung Heat, transforms Phlegm, and descends Lung Qi for Lung-Heat cough with thick, hard-to-expectorate sputum and chest or rib pain. Its salty quality softens hardness and dissipates nodules, so it is used for Phlegm-Fire goiter and scrofula.
It additionally promotes urination and drains Dampness for turbid, painful urination and vaginal discharge. Calcined and powdered (Hai Ge Fen), it restrains stomach acid and eases pain for acid regurgitation and epigastric pain. It is decocted or, when calcined, taken as powder and often wrapped in decoctions; used within formulas under professional guidance.
Botanical Description
Hai Ge Ke is the shell of marine clams, principally Cyclina sinensis and Meretrix meretrix (family Veneridae), and is therefore an animal-derived rather than botanical substance. The shells are roughly triangular to subcircular, 3 to 8 centimetres across, with concentrically ridged exteriors of varying coloration and smooth, porcellaneous, often violet-tinged interiors. Once collected from coastal mudflats and processed, the shells are calcined and ground to a fine pale powder for medicinal use. The source bivalves inhabit shallow brackish and marine sediments along the eastern and southern coasts of China and adjoining seas.
Active Constituents
Calcium carbonate (CaCO3)
Inorganic carbonate saltConcentration: ≥ 95% of dried shell
The dominant constituent of the clam shell, present chiefly as aragonite/calcite. It underlies the mineral's antacid and acid-neutralizing action (the basis of the calcined, powdered form used to control acidity and pain) and its traditional astringent, phlegm-transforming and nodule-softening effects.
Calcium oxide (CaO)
Inorganic oxideConcentration: Formed on calcination (Ge Ke duan)
Generated when the shell is calcined, as carbonate loses CO2. The more reactive oxide increases alkalinity and drying capacity, which classical practice associates with the calcined form's stronger acid-controlling and astringent activity.
Conchiolin (organic shell matrix)
Structural protein / glycoproteinConcentration: Minor (organic fraction)
The insoluble proteinaceous matrix that binds the mineral layers of the shell. It constitutes the small organic fraction of the drug and is largely lost on calcination.
Magnesium (as carbonate/oxide)
Alkaline-earth mineralConcentration: Trace
A minor alkaline-earth component that contributes, with calcium, to the overall acid-neutralizing capacity of the mineral drug.
Trace elements (Na, Sr, Cl, S)
Inorganic trace elementsConcentration: Trace
Sodium, strontium, chloride and sulfur are documented as minor elemental constituents. Variation in trace-element profile among shell-derived drugs is cited as a source of differing therapeutic emphasis.
⚠ Drug Interactions
Tetracycline and fluoroquinolone antibiotics
The high calcium carbonate content provides divalent calcium that chelates tetracyclines and fluoroquinolones in the gut, forming insoluble complexes that markedly lower oral bioavailability — a well-characterized effect of calcium-carbonate antacids.
Clinical note: Separate ingestion of the calcined shell powder from these antibiotics by at least 2–4 hours.
Levothyroxine
Calcium carbonate binds levothyroxine and raises gastric pH, decreasing its dissolution and absorption, as documented for calcium-carbonate supplements and antacids.
Clinical note: Administer at least 4 hours apart and monitor thyroid function if used concurrently.
Oral iron salts
Calcium competes with iron for intestinal absorption and the carbonate raises gastric pH, both of which reduce absorption of ferrous salts.
Clinical note: Space dosing of the shell powder and iron supplements.
Dosage
| Form | Amount | Frequency | Duration | Population | Notes |
|---|---|---|---|---|---|
| decoction | 6-15g | Daily | — | — | — |
Preparation Methods
Decoction (crushed, decocted first)
Parts: Shell
Crush the cleaned shell and decoct 6–15 g, adding it before the other herbs (cook first) because the mineral dissolves slowly. Used to clear Lung heat, transform phlegm and soften nodules.
Calcined powder (Ge Ke duan / Hai Ge Fen)
Parts: Shell
Calcine the shell until brittle, then grind to a fine powder. Taken 1.5–3 g wrapped in decoction or swallowed directly to control gastric acidity and relieve pain; also applied to nodules and phlegm accumulation.
Historical Texts
Shen Nong Ben Cao Jing (Divine Farmer's Materia Medica)
Eastern Han dynasty (c. 200 CE)Ben Cao Gang Mu (Compendium of Materia Medica), Li Shizhen
Ming dynasty (1578)References
- Zhang Y, et al.. Structural and Compositional Changes in Two Marine Shell Traditional Chinese Medicines: A Comparative Analysis Pre- and Post-Calcination . Journal of AOAC International (2024) [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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