Ge Qiao (Clam Shell)

Chinese Herb Actions

Chinese Herb Dosage

• What is the typical dosage of Ge Qiao, and why must a shell be cooked so long?

  10–15 g in decoction per Chen & Chen, and 6–15 g per Bensky — the two ranges our record holds. As with every shell medicinal, it is crushed and cooked first, ahead of the other herbs, because calcium carbonate is poorly soluble and a hard shell dropped into a short decoction gives up very little of itself.

  • Decoction — 10–15 g (Chen & Chen) or 6–15 g (Bensky), crushed and cooked first. The two sources overlap across most of their range; the difference is at the lower bound.
  • Powder — shell medicinals taken as a fine powder are swallowed whole rather than extracted, so powder doses across this group run far smaller than decoction doses and the two figures are never interchangeable. Our record carries a decoction figure only, so no powder dose is stated here.
  • Why extraction is the constraint — an analytical comparison of ark shell and clam shell confirmed that the amount of calcium carbonate actually dissolving into a decoction is limited, and that it rises after the shell is calcined (PMID 38492563). Long cooking and prior processing exist for the same reason: to get anything at all out of a rock.

  For comparison within the group: our Wa Leng Zi entry is recorded at 9–30 g in decoction or 1–3 g as powder, Zhen Zhu Mu at 10–25 g cooked first or roughly 1.5–3 g as levigated powder, and Hai Piao Xiao at roughly 6–12 g in decoction or 1.5–3 g as powder. Ge Qiao sits at the lower, more modest end of the shell doses.

  Source: Sacred Lotus sources & references (the recorded Chen & Chen and Bensky ranges for this herb, and the recorded ranges for Wa Leng Zi, Zhen Zhu Mu and Hai Piao Xiao, as held on file); dissolution behaviour per PMID 38492563, DOI 10.1093/jaoacint/qsae023. Reference only — not a prescription.

Chinese Herb Contraindications & Cautions

• Are there cautions for Ge Qiao (clam shell)?

  Our record states it plainly: do not use in cases of Yang deficiency, or Lung deficiency with cold. That is the pattern-level caution and it follows directly from what the herb is for — a cooling, phlegm-clearing shell has nothing to offer a cold, deficient Lung and will make it worse. The remaining cautions are contextual: what the material is made of, who should avoid it, and what else may be in a given batch.

  • Yang deficiency and Lung deficiency-cold — contraindicated, as recorded here.
  • Shellfish-derived (dietary, ethical and allergy reference note) — this is a mollusc shell. It is not suitable for strict vegans, and anyone with a shellfish allergy should know the origin before taking it.
  • It is a calcium load — at 6–15 g of a material that is largely calcium carbonate, this is a meaningful calcium intake. Anyone with hypercalcaemia, kidney stones, kidney impairment, or already taking calcium supplements or calcium-based antacids has an obvious reason to raise it with their prescriber. Precautionary, based on composition.
  • Cadmium in market material (quality reference note) — a survey of 10,245 samples across 279 types of Chinese herbal medicine, analysed by inductively coupled plasma mass spectrometry, placed Meretricis/Cyclinae concha among the materials showing a high-degree risk of cadmium contamination against the permissible limits used (PMID 33516113; DOI 10.1016/j.jhazmat.2021.125142). This names our material specifically, which is why it is reported here rather than as a generic claim about herbal medicines.
  • Microplastics in marine-derived material (quality reference note) — a survey of marine-derived Chinese medicines from two commercial suppliers detected microplastics in every product tested, clam shell included, at 0.07 to 9.53 items per gram, predominantly transparent fibres under 2 mm (PMID 37356768; DOI 10.1016/j.scitotenv.2023.165075).
  • Preparation matters — it must be crushed and cooked first for a decoction to contain much of anything, which makes it unsuitable for casual self-dosing.

  Source: Sacred Lotus sources & references (this herb's recorded caution against Yang deficiency and Lung deficiency-cold, and its recorded dose range, as held on file); category cautions per published materia medica consensus, cross-referenced against multiple online sources; contaminant findings per PMID 33516113 and PMID 37356768. Neutral reference disclosures, not usage instructions.

Chinese Herb Toxicity & Overdose

• Is Ge Qiao toxic?

  No. Our record carries no toxicity entry for Ge Qiao and does not class it among the toxic materia medica. Chemically it is close to inert: analytical work on clam shell confirms calcium carbonate as the dominant constituent, present as aragonite in the raw shell and converting to calcite after calcining, with calcium, sodium and strontium among the most abundant elements, and a small protein fraction that is largely destroyed by heating (PMID 38492563).

  • The realistic concerns are quality, not intrinsic toxicity — and unusually for a shell medicinal, they have been measured on this material by name. Cadmium contamination risk (PMID 33516113) and microplastic content (PMID 37356768) are both documented for market clam shell; see cautions.
  • Shellfish origin — an allergy consideration rather than a toxicity one, but worth knowing before use.
  • The usual caveat — no formal clinical safety evaluation of Ge Qiao could be found. Absence of reported toxicity is not the same as having been tested.

  Source: Sacred Lotus sources & references (the absence of a recorded toxicity entry for this herb, as held on file); composition per PMID 38492563, DOI 10.1093/jaoacint/qsae023; contaminant findings per PMID 33516113 and PMID 37356768. Neutral reference facts — not a safety guarantee.

Herb-Drug Interactions

• Does Ge Qiao interact with medications?

  No clinical herb–drug interaction study exists for Ge Qiao, but its composition gives a clear basis for practitioner awareness. The material is largely calcium carbonate — the same compound used as a conventional antacid — and one of the herb's own recorded actions is neutralising stomach acid. Two general consequences of taking a calcium carbonate antacid are therefore worth flagging as precautions rather than as findings: raising gastric pH can alter the absorption of medicines whose uptake depends on an acid stomach, and calcium can bind certain drugs in the gut so that less is absorbed — tetracycline and quinolone antibiotics, levothyroxine, bisphosphonates and iron salts being the usual examples.

  • This is inference from composition, not a measured interaction for this herb. No pharmacokinetic study of Ge Qiao with any drug could be found.
  • Practical position — anyone taking a medicine in those classes, or already on calcium supplements or calcium-based antacids, should mention any shell-derived herbal product to their prescriber.

  (Precautionary, based on constituent class; flagged for practitioner confirmation.)

Western / Biomedical Research

Chinese Herb Clinical Studies & Research

Provided as research context — a summary of published biomedical study, not a therapeutic or medical claim.

• Is there modern research on Ge Qiao (clam shell, Meretricis seu Cyclinae Concha)?

  Yes — and almost all of it is analytical chemistry, authentication and quality control rather than pharmacology. There are no clinical trials of the shell, and no laboratory study of its traditional phlegm-heat indications could be verified. That is unsurprising for a material that is essentially crushed calcium carbonate, and it is worth saying rather than dressing up.

  • Calcination changes the material measurably — infrared, X-ray and X-ray fluorescence spectroscopy plus thermogravimetric analysis of clam shell and ark shell from several production regions showed the calcium carbonate crystal form shifting from aragonite to calcite on calcining, protein content dropping significantly, and calcium carbonate dissolution in the decoction increasing afterwards, which the authors state aligns with the clinical use of calcined shell medicines. The same paper found no significant differences between production regions, and used principal component analysis of inorganic elements to separate the two shells (PMID 38492563; DOI 10.1093/jaoacint/qsae023). An earlier study quantified calcium carbonate decomposition at different calcining temperatures and compared commercially calcined shell drugs from six cities (PMID 7576136).
  • Telling the shells apart — a morphological and microscopic study of the five pharmacopoeial shell medicines, naming clam shell as Geqiao alongside abalone shell, ark shell, oyster shell and mother-of-pearl, established that both the whole drugs and their powders can be distinguished under normal and polarised light (PMID 26579467; PMC 4629281; DOI 10.1016/j.apsb.2015.03.014). Trace-element profiling by mass spectrometry across 51 batches found selenium the key discriminating element, with molybdenum, arsenic and zinc relatively stable in clam shell specifically (PMID 27071261), and near-infrared spectroscopy separated the same group by their organic content (PMID 25522614).
  • Quality risks in market material — a 10,245-sample heavy-metal survey placed clam shell among the materials at high-degree risk of cadmium contamination (PMID 33516113; DOI 10.1016/j.jhazmat.2021.125142), and microplastics were detected in every marine-derived Chinese medicine sampled from two suppliers, clam shell included (PMID 37356768; DOI 10.1016/j.scitotenv.2023.165075).

  Does research on the clam itself apply to Ge Qiao?

  No, and the distinction matters. There is an active biology and aquaculture literature on Meretrix meretrix and Cyclina sinensis — shell pigmentation genetics, disease resistance, pollutant accumulation — but it concerns the living animal and its soft tissue, not the dried shell used as a medicinal. Ge Qiao is the shell. Findings about the meat, the genome or the animal's ecology are not evidence for the herb, and we record the boundary rather than borrowing across it.

  Honest summary: the traditional indications for this shell — phlegm-heat cough, nodules, acid regurgitation — are untested by modern research. The acid-absorbing use has an obvious chemical rationale in calcium carbonate; the phlegm-transforming use has no modern mechanism, and we are not going to invent one.

  Sources: PMID 38492563, DOI 10.1093/jaoacint/qsae023 (composition and structural change before and after calcination); PMID 7576136 (calcium carbonate decomposition on calcining); PMID 26579467, PMC 4629281, DOI 10.1016/j.apsb.2015.03.014 (morphological and microscopic characterisation of five shell medicines, naming Geqiao); PMID 27071261 (trace elements across five shell medicines); PMID 25522614 (near-infrared identification); PMID 33516113, DOI 10.1016/j.jhazmat.2021.125142 (heavy metals in Chinese herbal medicine); PMID 37356768, DOI 10.1016/j.scitotenv.2023.165075 (microplastics in marine-derived Chinese medicines). Research context, not a therapeutic claim.

Chinese Herb Notes

• Is Ge Qiao the same as Hai Ge Ke or Hai Ge Qiao?

  Yes. Ge Qiao, Ge Ke, Hai Ge Ke and Hai Ge Qiao are names for the same material — clam shell — and our own record for this herb holds Ge Ke and Hai Ge Ke as its alternative names. Readers arriving under any of those spellings are in the right place; there is no separate herb hiding behind the longer name. The prefix simply marks it as the sea clam.

  • Confirmed in the analytical literature — a study of the five commonly used pharmacopoeial shell medicines names them by both their Latin and Chinese headings, giving Meretricis Concha as Geqiao alongside Haliotidis Concha (Shijueming), Arcae Concha (Walengzi), Ostreae Concha (Muli) and Margaritifera Concha (Zhenzhumu) (PMID 26579467; PMC 4629281). Our Ge Qiao is that entry.
  • The shell it is most often confused with is Wa Leng Zi — ark or cockle shell, Concha Arcae, a different mollusc and a separate entry on this site. The analytical literature repeatedly treats clam shell and ark shell as a matched pair of similar composition and efficacy (PMID 38492563), and the tradition assigns them different work: Ge Qiao is bitter, salty and neutral, enters Kidney, Lung and Stomach, and is filed under herbs that cool and transform phlegm-heat; Wa Leng Zi is sweet, salty and neutral, enters Liver and Spleen, and is filed under herbs that invigorate blood and remove stagnation. Both soften nodules and both absorb stomach acid, which is where they overlap in practice — for reflux or a nodule, phlegm-heat points to Ge Qiao and blood stasis or a fixed mass to Wa Leng Zi. See our Wa Leng Zi page for that entry in full.

  How does Ge Qiao compare with the other shell medicinals?

  All of them are calcium carbonate; what separates them is which job the tradition assigns to that calcium carbonate. Ge Qiao is the phlegm-heat shell — the only shell on this site filed under cooling and transforming phlegm-heat. Here is the group as we hold it.

  • Ge Qiao (this page, clam shell) — bitter, salty, neutral; Kidney, Lung, Stomach; clears heat and transforms phlegm, softens nodules, mildly promotes urination, absorbs acid. The chest-and-phlegm shell.
  • Wa Leng Zi (Concha Arcae, ark or cockle shell) — sweet, salty, neutral; Liver and Spleen; filed under blood-invigorating. Invigorates blood, softens hardness, disperses masses, absorbs acid. Its closest sibling chemically and its clearest contrast functionally: masses rather than phlegm.
  • Mu Li (Concha Ostreae, oyster shell) — salty, astringent, cool; Liver and Kidney; filed under substances that anchor, settle and calm the spirit. Also softens hardness and, calcined, controls acid.
  • Zhen Zhu Mu (Concha Margaratiferae, mother-of-pearl) — sweet, salty, cold; Heart and Liver; anchors Liver yang, settles the spirit, brightens the eyes.
  • Zhen Zhu (Margarita, pearl) — sweet, salty, cold; Heart and Liver. The same nacre in its most concentrated and most expensive form; spirit-settling and topical.
  • Shi Jue Ming (Concha Haliotidis, abalone shell) — salty, cold; Kidney and Liver; filed under substances that extinguish wind and stop tremors. The eye-and-Liver-yang shell; the fifth of the pharmacopoeial group named above, and held here under its own entry.
  • Hai Piao Xiao (Os Sepiae seu Sepiellae, cuttlefish bone) — salty, astringent, slightly warm; Kidney, Liver, Stomach; filed under herbs that astringe, stabilise and bind. The acid-and-bleeding shell, and the closest comparison for the acid-regurgitation indication specifically.

  Why is clam shell usually calcined, and what does that change?

  Calcining — heating the shell until it is brittle, then breaking it up — is the standard processed form for this material, and it exists because it makes the shell give up more of itself. This is recorded here as reference fact about a pharmacy process; it is not a preparation instruction and should not be attempted domestically.

  • What changes chemically — a comparative analysis of ark shell and clam shell before and after calcination found the calcium carbonate crystal form converting from aragonite in the raw shell to calcite in the calcined shell, protein content falling sharply, and calcium carbonate dissolution in the decoction rising afterwards — which the authors state aligns with the clinical use of calcined shell medicines (PMID 38492563; DOI 10.1093/jaoacint/qsae023). Earlier work measured how fast calcium carbonate decomposes at different calcining temperatures and used it as a simple quality check on commercially calcined shell drugs (PMID 7576136).
  • Why it matters to a reader — a label reading “calcined” is not a formality. Across the shell group it signals which of the material's traditional actions it was prepared for, and it measurably changes how much of the shell a decoction can actually extract.

  Identity note flagged, not corrected: our Latin field reads Concha Cyclinae Sinensis, naming a single species (Cyclina sinensis). The pharmacopoeial heading used throughout the analytical literature is the broader Meretricis seu Cyclinae Concha — that is, shells of either the hard clam Meretrix or Cyclina sinensis are dispensed under this one name (PMID 38492563; PMID 33516113; PMID 26579467). Our field is not wrong so much as narrower than the drug it names. We have left it exactly as held; whether to broaden it is an owner decision. Our record also carries no separate common-name variants beyond Ge Ke and Hai Ge Ke.

  Formula context: our own formula records do not currently link Ge Qiao to any formula, so no formula is named here.

  Source: Sacred Lotus sources & references (the herb records for Ge Qiao, Wa Leng Zi, Mu Li, Zhen Zhu Mu, Zhen Zhu, Shi Jue Ming and Hai Piao Xiao — identity, alternative names, nature, flavour, channels and category — as held on file, and the absence of any formula link for this herb); naming per PMID 26579467, PMC 4629281; calcination chemistry per PMID 38492563 and PMID 7576136; pharmacopoeial heading per PMID 38492563 and PMID 33516113. Reference facts, not preparation instructions.