Herb

Wa Leng Zi (Duan)

Cockle shells (processed) | 煅瓦楞子

Also known as:

Cockle Shell

Wa Leng Zi (Duan)

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Properties

Blood-invigorating and stasis-dispelling herbs (活血化瘀药) · Neutral

Traditionally supports*

Digestive Health Acid Reflux Relief Thyroid and Lymph Node Support Women's Health

Parts Used

Shell (壳 ké / 甲 jiǎ)

*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

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About This Herb

Traditional Chinese Medicine background and properties

Herb Description

Wa Leng Zi is the shell of ark clams, used in Chinese medicine to break down stubborn Phlegm, soften hard lumps, and relieve stomach acid and pain. It is most commonly used for acid reflux, stomach ulcers, thyroid nodules, and abdominal masses. Its calcined form is especially valued for neutralizing excess stomach acid.

Herb Category

Blood-invigorating and stasis-dispelling herbs (活血化瘀药) Phlegm-transforming herbs (化痰药)

Main Actions

  • Resolves Phlegm and transforms stasis
  • Dissipates Nodules and Softens Hardness
  • Controls Acidity and Stops Pain
  • Invigorates Blood and disperses accumulations

How These Actions Work

'Resolves Phlegm and transforms stasis' (消痰化瘀) means this herb can break down old, stubborn Phlegm that has congealed in the body, as well as move stagnant Blood. Its salty taste has a natural ability to penetrate and dissolve thick accumulations. This is why it is used for thick, sticky sputum that is difficult to cough up, or for masses in the abdomen caused by a combination of Phlegm and Blood stasis.

'Softens hardness and dissipates nodules' (软坚散结) means it can reduce firm lumps and swellings. In TCM, the salty taste is understood to soften hard masses. This action is particularly relevant for conditions like goiter (yǐng liú 瘿瘤), lymphatic nodules known as scrofula (luǒ lì 瘰疬), thyroid nodules, and breast lumps where Phlegm or Blood stasis has solidified into palpable masses.

'Controls acid and alleviates pain' (制酸止痛) refers to the herb's well-known ability to neutralize excess stomach acid and relieve stomach pain. This action is strongest in the calcined (煅 duàn) form, where the shell's calcium carbonate converts to calcium oxide, which more effectively neutralizes acid. It is used for heartburn, acid reflux, and ulcer-related stomach pain.

'Invigorates Blood and disperses accumulations' (活血消积) means it helps move Blood that has become stuck, particularly in the abdomen. Because the salty taste enters the Blood level, this herb can address fixed abdominal masses caused by Blood stasis, Qi stagnation, or Phlegm accumulation.

Patterns Addressed

In TCM, symptoms cluster into recognizable patterns of disharmony that reveal what's out of balance in the body. Wa Leng Zi is traditionally associated with these specific patterns.

The following describes this herb's classification within Traditional Chinese Medicine theory and is provided for educational purposes only.

Why Wa Leng Zi addresses this pattern

Wǎ Léng Zǐ's salty taste gives it a natural ability to soften hard masses and dissolve congealed Phlegm. When Phlegm accumulates and solidifies over time, it forms palpable nodules such as thyroid swellings (goiter), lymphatic lumps (scrofula), or breast nodules. The herb enters the Lung and Liver channels, allowing it to address Phlegm stagnation in the throat and neck (Lung channel area) as well as masses along the Liver channel. Its neutral temperature means it can be used regardless of whether the underlying condition is hot or cold in nature.

A practitioner would look for one or more of these signs

Goiter

Neck swelling due to Phlegm congealing

Scrofula

Lymphatic nodules, especially in the neck

Nodules

Firm, palpable masses in the thyroid area

TCM Properties

Temperature

Neutral

Taste

Salty (咸 xián), Sweet (甘 gān)

Channels Entered
Lungs Stomach Liver
Parts Used

Shell (壳 ké / 甲 jiǎ)

This is partial information on the herb's TCM properties. More detailed information is available on the herb's dedicated page

Product Details

Manufacturing, supplier, and product specifications

Product Type

Granules

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Botanical & Sourcing

Quality Indicators

Good quality Wa Leng Zi shells are thick, sturdy, and intact with clearly visible radiating ribs (the "tile ridges") on the outer surface. The shell should be white or greyish-white on the inside, smooth, and without foul odor. The taste should be bland. For the raw (unprocessed) form, shells with prominent and well-defined ribbing are considered superior. For calcined Wa Leng Zi (Duan Wa Leng Zi), the pieces should be grey-white, with the lustrous sheen of the raw shell gone, and the texture should be brittle and easily crumbled rather than still hard and glassy. The powder of properly calcined material should be a deep grey color with no remaining hard granules. The current market primarily uses the larger Inflated Ark (Kui Han) and Hairy Ark (Mao Han) shells; the smaller Mud Ark shells are less commonly traded.

Primary Growing Regions

Wa Leng Zi is sourced from the coastal waters of China. The primary producing regions are Shandong province (especially the Shandong Peninsula area around Yangjiaogou), Zhejiang, Fujian, and Guangdong, where ark shells are both wild-harvested and commercially farmed in shallow tidal flats. Mud Ark (Arca granosa) is widely cultivated along the southeastern coast. The Hairy Ark Shell (Arca subcrenata) is also found around Tianjin (Tanggu) and Liaoning (Liaohe estuary). The Inflated Ark (Arca inflata) is distributed across the Yellow Sea, Bohai Sea, East China Sea, and South China Sea.

Harvesting Season

Autumn and winter through the following spring. Shells are collected from shallow coastal mud flats, boiled briefly to remove the meat, then dried.

Supplier Information

Treasure of the East

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Miscellaneous Info

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Usage & Safety

How to use this herb and important safety information

Important Medical Disclaimer

The information provided here is for educational purposes only and is not intended as medical advice or to replace consultation with a qualified healthcare professional. This herb is a dietary supplement and has not been evaluated by the FDA. It is not intended to diagnose, treat, cure, or prevent any disease.

Always consult with a qualified healthcare provider, particularly if you are pregnant, nursing, have a medical condition, or are taking other medications. Discontinue use and consult your healthcare provider if you experience any adverse reactions.

Recommended Dosage

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Instructions for safe storage and consumption

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Traditional Dosage Reference

Standard

9-15g

Maximum

Up to 30g in decoction, crushed and decocted first, under practitioner supervision. As a non-toxic mineral substance, higher doses are sometimes used clinically for stubborn phlegm or masses.

Notes

The raw (unprocessed, crushed) form is preferred for dissolving phlegm, dispersing blood stasis, and softening hardness in conditions such as abdominal masses, goiter, and scrofula. The calcined form (Duan Wa Leng Zi) is preferred for neutralizing stomach acid and relieving stomach pain, as calcination converts the calcium carbonate to calcium oxide, which has stronger acid-neutralizing properties. For powder use (taken directly rather than decocted), the dose is typically 1-3g per serving, two to three times daily. When used in decoction, the shell must be crushed and decocted first (Xian Jian) for at least 20-30 minutes before adding other herbs, due to its hard mineral nature.

Processing Methods

Processing method

Clean shells are placed in a suitable container and calcined over smokeless fire until red-hot and brittle, then removed, cooled, and crushed into pieces or powder.

How it changes properties

Calcination converts the main component from calcium carbonate to calcium oxide, which is far more effective at neutralizing stomach acid (water extracts of the calcined form contain 4.6 times more calcium salts than the raw form). The calcined form becomes brittle and easy to powder for direct ingestion. The thermal nature shifts slightly warmer. The acid-neutralizing and pain-relieving action is greatly enhanced, while the Blood-invigorating and Phlegm-dispersing actions become secondary.

When to use this form

Use the calcined form whenever the primary goal is to control stomach acid and relieve stomach pain, such as in gastric or duodenal ulcers, acid reflux, and chronic gastritis with acid regurgitation.

Toxicity Classification

Non-toxic

Wa Leng Zi is classified as non-toxic in the classical literature. The Ben Cao Gang Mu records it as having no toxicity. The shell is composed almost entirely of calcium carbonate (over 90%) with small amounts of calcium phosphate, silicates, and trace minerals. No toxic components have been identified. The classical processing instruction to quench calcined shells in vinegar multiple times was said to "remove fire toxicity" (出火毒), which is understood as a precaution to temper the harshness of the freshly calcined mineral product rather than to address inherent toxicity. In clinical reports of treating peptic ulcer, some patients showed mild side effects including facial edema or urinary cloudiness, but these were uncommon.

Contraindications

Avoid

Pregnancy: Wa Leng Zi has blood-invigorating (activating) properties that may stimulate the uterus and pose a risk of fetal instability or miscarriage.

Avoid

Known allergy to shellfish or shell-derived substances. Allergic reactions including skin rash or itching may occur.

Caution

Active bleeding conditions or bleeding tendency (frequent gum bleeding, easy bruising, heavy menstrual bleeding). The herb's blood-invigorating action may worsen bleeding.

Caution

Absence of blood stasis, phlegm accumulation, or acid reflux. Using this herb without an appropriate pattern indication may damage the Stomach, potentially causing nausea or bloody stool.

Caution

Hepatitis or active liver inflammation. The strongly salty nature of the herb, entering the Liver channel, may aggravate liver conditions.

Caution

Menstruating women should use with caution due to the herb's blood-moving properties, which may increase menstrual flow.

Special Populations

Pregnancy

Contraindicated during pregnancy. Wa Leng Zi has well-recognized blood-invigorating and stasis-dispersing properties. These actions may stimulate uterine activity and compromise fetal stability. Classical and modern sources alike caution that pregnant women should avoid this herb, as its blood-moving effects could potentially lead to uterine bleeding or miscarriage.

Breastfeeding

No specific classical or modern prohibitions exist for breastfeeding, but caution is advised. As a blood-invigorating mineral substance whose components could theoretically be absorbed and transferred through breast milk, it should only be used during breastfeeding under professional guidance and at the lowest effective dose. The calcium content itself is generally not a concern, but the blood-moving properties warrant caution for nursing mothers.

Pediatric Use

Wa Leng Zi can be used in children but requires dosage reduction proportional to the child's age and body weight. Children's organ systems are not fully developed, so the adult dose should not be applied. Standard pediatric dose reduction principles apply. The calcined form is preferred for children with acid reflux or stomach pain, as it is milder. Use in children should always be under the guidance of a qualified practitioner.

Drug Interactions

No well-documented interactions with specific pharmaceutical drugs have been established in peer-reviewed literature. However, based on its pharmacological composition (primarily calcium carbonate), the following theoretical interactions should be considered:

  • Antacids and acid-suppressing drugs (e.g. proton pump inhibitors, H2 blockers): The calcined form acts as a calcium-based antacid, so concurrent use may lead to excessive acid neutralization or altered gastric pH, potentially affecting absorption of other medications.
  • Tetracycline and fluoroquinolone antibiotics: Calcium-rich substances can chelate with these antibiotics, reducing their absorption and efficacy. A gap of at least 2 hours between taking Wa Leng Zi and these antibiotics is advisable.
  • Iron supplements: Calcium may interfere with iron absorption when taken simultaneously.
  • Cardiac glycosides (e.g. digoxin): Large amounts of calcium may theoretically potentiate the effects of cardiac glycosides, though this is primarily a concern with very high calcium intake.

Dietary Advice

When taking Wa Leng Zi for stomach acid or gastric pain, avoid acidic, spicy, and greasy foods that may aggravate stomach conditions. Alcohol and raw, cold foods should also be minimized. When using the herb for phlegm-dissolving or mass-dispersing purposes, avoid excessively greasy or phlegm-producing foods such as dairy, fried foods, and sweets, which may counteract the herb's therapeutic action.

Cautions & Warnings

Although this herb is typically safe for most individuals, it may cause side effects in some people. Pregnant women, nursing mothers, postpartum women, and those with liver disease should use the formula with caution.

As with any Chinese herbal remedy, it is advisable to seek guidance from a qualified TCM practitioner before beginning treatment.