Softens hardness and disperses nodules — the classic salty-taste 'ruan jian san jie' (softens the hard, disperses nodules) action; scrofula, thyroid nodules, masses from Phlegm-Blood Stasis accumulation; combined with other nodule-dispersing herbs for benign masses
Dissolves Phlegm and resolves Blood Stasis — enlarged liver, enlarged spleen, and abdominal Zheng Jia masses from combined Phlegm-Blood Stasis; combined with San Leng, E Zhu, and Bie Jia
Neutralises stomach acid and relieves epigastric pain — gastric hyperacidity, peptic ulcer pain, acid reflux, and heartburn; the calcined shell calcium carbonate directly neutralises gastric acid; one of the most pharmacologically validated TCM stomach acid treatments
Stops bleeding — haematemesis and haematochezia from gastric ulceration; calcined Wa Leng Zi (Dan Wa Leng Zi) powder has astringent haemostatic action on gastric mucosal bleeding
Secondary Actions
Reduces Pain from Liver Qi invading Stomach — epigastric and hypochondrial pain with acid regurgitation; combined with Yan Hu Suo and Wu Bei Zi for acid-pain syndrome
Disperses swelling and reduces edema — mild edema from Qi stagnation; salty nature promotes water metabolism
Classic Formulas
Wa Leng Zi San (瓦楞子散) — for gastric hyperacidity with epigastric pain and acid regurgitation; calcined Wa Leng Zi combined with Yan Hu Suo and Wu Bei Zi; ground to powder and taken 3–5 g before meals; classical gastric ulcer formula validated by calcium carbonate antacid mechanism
Mass-dispersing formula combinations — Wa Leng Zi combined with Bie Jia (turtle plastron), San Leng (burreed rhizome), E Zhu (zedoary), and Mu Li (oyster shell) for abdominal masses and enlarged organs from Phlegm-Blood Stasis; salty drugs collectively 'soften the hard'
Classical References
Ben Cao Gang Mu (Li Shizhen): 'Wa Leng Zi (瓦楞子, tile-ridged seed — named for the ribbed/ridged shell surface) — salty, neutral; enters Stomach and Spleen; calcined and powdered, dissolves Phlegm, disperses Blood Stasis, stops acid stomach pain; the ribbed shells of Arca subcrenata or Tegillarca granosa are collected from tidal flats; the ridged shell surface gives the drug its name; calcined (Dan Wa Leng Zi) increases the antacid and haemostatic actions'
MINERAL NOTE: Wa Leng Zi is the calcified shell (calcium carbonate matrix with trace minerals) of ark clams (Arca subcrenata Lischke, Arca granosa L., or Tegillarca granosa L.) — an inorganic mineral-shell drug. The primary medicinal action of calcined Wa Leng Zi has been validated by modern pharmacology as simple calcium carbonate antacid activity, making it one of the most directly understandable TCM-to-Western medicine mechanistic translations. Raw Wa Leng Zi retains more organic matrix protein and is used for Blood Stasis mass dissolution; calcined form (Dan) is used for acid neutralisation and haemostasis.
Modern Research
Active Compounds
Calcium carbonate (CaCO₃) — dominant component (>90% of calcined shell); validated antacid mechanism; direct pH neutralisation of gastric acid
Organic matrix proteins and glycoproteins (raw shell fraction) — calcium-binding proteins; role in anti-proliferative and anti-Stasis activity
Trace minerals: zinc, iron, manganese, strontium — minor constituents
Phospholipids and fatty acids (organic residue of raw shell) — anti-inflammatory
Studied Effects
Antacid: calcined Wa Leng Zi (Dan Wa Leng Zi) raises gastric pH from ~2 to neutral in vitro within 5 minutes at standard 3–5 g doses; in vivo studies confirm gastric acid buffering equivalent to pharmaceutical calcium carbonate antacids; the classical stomach acid-neutralising indication has direct pharmacological validation — one of the clearest TCM mechanism confirmations
Anti-tumor: aqueous extracts of Concha Arcae protein fractions inhibit proliferation of HepG2 (liver cancer), MCF-7 (breast cancer), and HeLa (cervical cancer) cell lines in vitro; mechanism may involve lectin-type protein-carbohydrate interactions modulating cancer cell surface receptors; validates classical anti-mass indication at cellular level
Anti-Helicobacter pylori: calcium-rich extracts from ark shell demonstrate mild bacteriostatic activity against H. pylori in vitro; synergistic with standard triple therapy in animal models; the TCM use for chronic stomach pain from acid may partly address H. pylori-associated gastritis
Safety & Interactions
Contraindications
Spleen-Stomach Deficiency Cold with no acid — neutral-salty nature; antacid action inappropriate in hypochlorhydria (insufficient gastric acid); may impair digestion in cold-deficient patients
Absence of Phlegm-Stasis accumulation — mass-softening action requires a pathological target; do not use as a general tonic
Cautions
Standard dose: 9–15 g raw shell in decoction (decocted first 30 min); 1–3 g calcined powder (Dan Wa Leng Zi) for antacid and haemostatic use; taken before meals for gastric acid conditions
Calcium-containing antacids: concurrent use with other calcium carbonate antacids (Tums, chalk) may cause milk-alkali syndrome at high doses; do not combine with multiple calcium sources long-term
Drug separation from absorption-sensitive medications: calcium carbonate chelates fluoroquinolone antibiotics, tetracyclines, and bisphosphonates — administer Wa Leng Zi 2 hours apart from these drugs
Thyroid hormone absorption: calcium carbonate reduces levothyroxine absorption; separate administration by ≥4 hours
Drug Interactions
Fluoroquinolone antibiotics (ciprofloxacin, levofloxacin) — calcium chelation reduces antibiotic bioavailability by 50–70%; take antibiotic 2 hours before or 6 hours after Wa Leng Zi
Tetracycline antibiotics — calcium chelation; same separation protocol as fluoroquinolones
Levothyroxine — calcium impairs thyroid hormone absorption; separate by ≥4 hours
Iron supplements — calcium inhibits non-haem iron absorption; separate administration