What patterns does Peng Sha address?

Peng Sha addresses these TCM patterns of disharmony: Heat-Toxin Accumulation, Phlegm-Heat in the Lungs, Liver Fire Flaring Upward.

What conditions is Peng Sha used for?

Peng Sha is commonly used for: Sore Throat, Mouth Ulcers, Oral Thrush, Gouty Inflammation, Viral Conjunctivitis, Corneal Opacity, Hypochondrial Pain That Is Worse On Coughing And Breathing, Vaginal Yeast Infection, Otitis Media, Stomatitis. A TCM practitioner would consider this herb when these conditions arise from the specific patterns it addresses.

Ingredient Mineral (矿物 kuàng wù)

Peng Sha

Q: What are the TCM actions of Peng Sha?

The TCM actions of Peng Sha include: Clears Heat and Resolves Toxicity, Promotes Tissue Regeneration and Heals Sores, Clears Lung Heat and Transforms Phlegm, Brightens the Eyes and Removes Visual Obstructions.

Borax · 硼砂

Na₂B₄O₇·10H₂O · Borax

Also known as: Péng Shā (蓬砂), Péng Shā (鹏砂), Yuè Shí (月石), Dà Péng Shā (大朋砂), Pén Shā (盆砂), Borax, Sodium tetraborate decahydrate

Images shown are for educational purposes only

Péng Shā (Borax) is a mineral substance used primarily as a topical remedy in Chinese medicine for sore throats, mouth ulcers, oral thrush, and eye inflammation. Its cool, sweet-salty nature clears Heat and toxins from the mouth, throat, and eyes when applied as a fine powder or dissolved in water. While it can be taken internally in very small doses to help clear sticky Phlegm from the Lungs, modern practice overwhelmingly favours external use due to safety concerns with oral ingestion.

Category Substances for external application (外用药) Herbs that draw out toxins and generate flesh (拔毒生肌药)

Therapeutic focus Oral and Dental Health Throat Health Eye Health and Vision Skin Health

TCM Properties

Temperature

Cool

Taste

Sweet (甘 gān), Salty (咸 xián)

Channels entered

Lungs, Stomach

Parts used

Mineral (矿物 kuàng wù)

Educational content • Consult qualified TCM practitioners for diagnosis and treatment

What This Ingredient Does

Every ingredient has a specific set of actions — here's what Peng Sha does in the body, explained in both everyday and TCM terms

Therapeutic focus

In practical terms, Peng Sha is primarily used to support these areas of health:

Oral and Dental Health Throat Health Eye Health and Vision Skin Health

TCM Actions

In TCM terminology, these are the specific therapeutic actions that Peng Sha performs to restore balance in the body:

Clears Heat and Resolves Toxicity Promotes Tissue Regeneration and Heals Sores Clears Lung Heat and Transforms Phlegm Brightens the Eyes and Removes Visual Obstructions

How these actions work

'Clears Heat and resolves toxins (external use)' is the primary action of Péng Shā. Its cool nature and sweet-salty taste allow it to clear Heat-toxin from the throat, mouth, and eyes when applied topically. This is why it is a staple in throat and eye powders for conditions like sore throat, mouth ulcers, and oral thrush. The Ben Cao Gang Mu describes its ability to treat "upper burner Phlegm-Heat, generate fluids, and address mouth, throat, and eye disorders."

'Relieves swelling and prevents putrefaction' refers to Péng Shā's antiseptic and anti-inflammatory properties when used externally. It helps keep wounds and ulcerated surfaces from becoming infected and promotes healing. In its raw form it is primarily used for this antimicrobial and anti-putrefactive action, while the calcined form shifts more toward astringency and tissue regeneration.

'Clears the Lungs and resolves Phlegm (internal use)' makes use of its salty taste (which softens hardness) and cool nature to dissolve thick, sticky Phlegm caused by Heat in the Lungs. This internal use is reserved for cases of Phlegm-Heat cough with yellow, viscous sputum, especially when accompanied by a sore, swollen throat. However, modern practice rarely uses Péng Shā internally due to toxicity concerns, and internal dosage should be carefully limited to 1.5 to 3 grams in pill or powder form.

'Removes nebulae and improves vision' describes Péng Shā's use in ophthalmology. When dissolved in water as an eye wash or combined with other eye-clearing minerals like Lú Gān Shí (Calamine) and Bīng Piàn (Borneol), it can help clear superficial corneal opacities (pterygium, nebulae) caused by Wind-Heat or Liver Fire rising to the eyes.

Patterns Addressed

In TCM, symptoms cluster into recognizable patterns of disharmony. Peng Sha is used to help correct these specific patterns.

Why Peng Sha addresses this pattern

Péng Shā's cool thermal nature and sweet-salty taste make it well suited for clearing Heat-toxin that accumulates in the upper body, particularly the mouth, throat, and eyes. Its salty taste softens swelling and hardness, while its sweet taste helps resolve toxins. Applied externally, it directly addresses the local inflammation, swelling, ulceration, and tissue damage caused by Heat-toxin flaring upward through the Lung and Stomach channels. This is why it is a core ingredient in classical topical powders for acute throat obstruction, mouth sores, and oral infections.

A practitioner would look for one or more of these signs

Sore Throat

Acute swelling and pain in the throat

Mouth Ulcers

Painful sores on the tongue, gums, or oral mucosa

Oral Thrush

White patches in the mouth (thrush), especially in children

Gouty Inflammation

Red, swollen, painful gums

Why Peng Sha addresses this pattern

When taken internally, Péng Shā enters the Lung channel where its cool nature clears Lung Heat, and its salty taste dissolves thick, sticky Phlegm that is difficult to expectorate. This combination targets the root mechanism of Phlegm-Heat in the Lungs: Heat condenses fluids into viscous Phlegm, and the salty-cool nature of Péng Shā both cools the Heat and softens the congealed Phlegm. It is especially appropriate when Phlegm-Heat cough is accompanied by throat swelling and pain, as its Heat-clearing action benefits both the Lungs and the throat simultaneously.

A practitioner would look for one or more of these signs

Hypochondrial Pain That Is Worse On Coughing And Breathing

Cough with thick, yellow, sticky sputum that is hard to expectorate

Sore Throat

Throat pain accompanying the cough

Hoarseness

Hoarse voice from prolonged Phlegm-Heat irritation

Why Peng Sha addresses this pattern

When Liver Fire or Wind-Heat rises to the eyes, it can cause redness, swelling, pain, and the formation of superficial corneal opacities (nebulae or pterygium). Péng Shā's cool nature clears this ascending Heat from the eye region. Although it primarily enters the Lung and Stomach channels, its topical application as an eye wash or in eye-drop powders allows it to directly address the local accumulation of Heat in the eyes. Its ability to 'remove nebulae' (消障翳) is a specific ophthalmological application for superficial corneal lesions caused by pathogenic Heat.

A practitioner would look for one or more of these signs

Eye Redness

Red, bloodshot eyes with swelling and pain

Blurry Vision

Blurred vision from corneal opacities or pterygium

Eye Pain

Burning, stinging eye pain from Heat

Commonly Used For

These are conditions where Peng Sha is frequently used — but only when they arise from the specific patterns it addresses, not in all cases

Arises from: Heat-Toxin Accumulation

TCM Interpretation

In TCM, mouth ulcers (oral aphthae) are most commonly understood as an expression of Heat-toxin, often originating from Stomach Fire or Heart Fire that rises along the channels to the oral cavity. The Stomach channel passes through the gums and mouth, and the Heart opens to the tongue. When Heat accumulates in these organ systems (from diet, emotional stress, or constitutional factors), it scorches the oral tissues, causing the characteristic painful, red-bordered sores. In some cases, the pattern may involve Yin Deficiency generating Empty Fire that rises to the mouth, though Péng Shā is more suited to excess Heat presentations.

Why Peng Sha Helps

Péng Shā directly addresses oral ulcers through its topical Heat-clearing and toxin-resolving action. Its cool thermal nature quenches the Heat burning the oral mucosa, while its sweet taste helps resolve toxins and its salty taste reduces swelling and softens hardened, inflamed tissue. Applied as a fine powder to the ulcer surface, it also exerts an antiseptic and anti-putrefactive effect that protects the raw tissue from secondary infection. This is the rationale behind its inclusion in Bīng Péng Sǎn (Borneol and Borax Powder), the most widely used classical formula for mouth and throat sores, where it works alongside Bīng Piàn (Borneol) and Xuán Míng Fěn (Glauber's salt) to clear Heat, reduce swelling, and relieve pain.

Arises from: Heat-Toxin Accumulation

TCM Interpretation

Sore throat in TCM is broadly attributed to pathogenic Heat invading or accumulating in the throat region. This can be caused by external Wind-Heat invasion or internal Heat from the Lungs and Stomach flaring upward. Severe cases like 'throat obstruction' (喉痹 hóu bì) and 'wind wrapping the throat' (缠喉风 chán hóu fēng) involve intense Heat-toxin causing dangerous swelling and obstruction. The throat is where the Lung and Stomach channels converge, making it vulnerable to Heat from both organ systems.

Why Peng Sha Helps

Péng Shā enters both the Lung and Stomach channels, targeting the two main sources of throat Heat. Its cool nature directly clears this Heat, while its salty taste softens swelling and its sweet taste detoxifies. For severe sore throat, it can be dissolved in the mouth to slowly release its active substance, allowing direct contact with the inflamed tissue. Classical formulas use it either alone (dissolved and held in the mouth) or with partners like Bīng Piàn (Borneol) and Xuán Míng Fěn to create topical throat powders. Its antiseptic properties also help prevent infection in ulcerated throat tissue.

Also commonly used for

Oral Thrush

Thrush (goose-mouth sores), especially in infants

Gouty Inflammation

Gingivitis and gum erosion

Corneal Opacity

Superficial corneal nebulae and pterygium

Hypochondrial Pain That Is Worse On Coughing And Breathing

Productive cough with thick yellow phlegm from Lung Heat

Vaginal Yeast Infection

Candidal vaginitis (topical application)

Otitis Media

Chronic middle ear infection with discharge

Stomatitis

Oral mucositis and stomatitis

Ingredient Properties

Every ingredient has an inherent temperature, taste, and affinity for specific channels — these properties determine how it interacts with the body

Temperature

Cool

Taste

Sweet (甘 gān), Salty (咸 xián)

Channels Entered

Lungs Stomach

Parts Used

Mineral (矿物 kuàng wù)

Dosage & Preparation

These are general dosage guidelines for Peng Sha — always follow your practitioner's recommendation, as dosages vary based on the formula and your individual condition

Standard dosage

1.5–3g (internal, in pill or powder form only)

Maximum dosage

Do not exceed 3g internally. The adult toxic dose range begins at 1–3g with cumulative daily use. Lethal dose is approximately 15g for adults.

Dosage notes

Peng Sha is primarily used externally. For external application, use an appropriate amount of fine powder applied directly, mixed into pastes, or dissolved in warm water as a gargle or wash. For internal use, the standard dose is 1.5 to 3g, administered only in pill or powder form, never as a standard decoction. Internal use should be strictly short-term. For epilepsy treatment (a historically documented use), doses of 0.3 to 1g were given three to four times daily, but this requires professional supervision and concurrent supportive therapy. Raw borax (Sheng Peng Sha) is preferred for clearing Heat and resolving toxins; calcined borax (Duan Peng Sha) has stronger astringent and drying properties and is preferred for weeping skin lesions and damp sores.

Preparation

Peng Sha is NOT decocted in the standard manner. For internal use, it must be ground into fine powder and taken in pill or powder form (1.5–3g). For external use, grind into an extremely fine powder and apply directly to the affected area (mouth sores, throat), or dissolve in hot water for use as a gargle or wash. Calcined borax (Duan Peng Sha) is prepared by dry-frying crushed borax over high heat until it puffs up and expands into a white, friable mass, then cooled and ground to a fine powder. The raw form is better for clearing Heat and toxins; the calcined form is better for astringent and anti-putrefactive external applications.

Processing Methods

In TCM, the same ingredient can be prepared in different ways to change its effects — here's how processing alters what Peng Sha does

Processing method

Raw Péng Shā is broken into small pieces and placed in a dry pan over high heat. It is stir-fried until it swells, forms small bubbles, releases all moisture, and becomes a white, porous, spongy mass with no crackling sounds. It is then removed, cooled, and ground into a fine powder.

How it changes properties

Calcination removes the crystal water, making the substance lighter, more porous, and more astringent. While raw Péng Shā emphasises clearing Heat-toxin and preventing putrefaction (anti-septic), the calcined form shifts toward stronger astringent and tissue-regenerating properties. A classical saying captures this: 'Raw form dissolves decay; calcined form regenerates tissue' (生则化腐，煅枯则生肌). The core thermal nature (cool) and taste (sweet, salty) remain, but the clinical emphasis shifts from antimicrobial to wound-healing.

When to use this form

Use calcined Péng Shā when the goal is to dry weeping lesions, astringe raw tissue, and promote tissue regeneration. This form is preferred for chronic, non-healing ulcers, oozing sores, and the later stages of wound healing where the infection has been controlled but the tissue needs help closing. It is also the form used in Bīng Péng Sǎn according to the Chinese Pharmacopoeia.

Common Ingredient Pairs

These ingredients are traditionally combined with Peng Sha for enhanced therapeutic effect

Bing Pian Péng Shā 5 qián : Bīng Piàn 5 fēn (10:1 by weight)

Péng Shā clears Heat-toxin and prevents putrefaction while Bīng Piàn (Borneol) opens orifices with its aromatic, penetrating nature and provides additional cooling and pain relief. Together they create a powerful topical combination that detoxifies, reduces swelling, and stops pain in the mouth and throat far more effectively than either alone.

When to use: Acute sore throat, mouth ulcers, oral thrush, gum inflammation, and tongue swelling from Heat-toxin. This pair forms the core of Bīng Péng Sǎn.

Xuan Ming Fen 1:1 (equal parts)

Péng Shā clears Heat-toxin and prevents tissue decay, while Xuán Míng Fěn (calcined Glauber's salt) clears Heat, softens hardness, and disperses accumulations. Together their salty-cool natures synergize to strongly clear upper burner Heat-toxin, reduce swelling, and dissolve hardened, inflamed tissue in the mouth and throat.

When to use: Severe throat swelling, painful mouth sores, and gum erosion where significant swelling and hardness need to be resolved. Both are key ingredients in Bīng Péng Sǎn.

Lu Gan Shi Varies by formula; typically combined in equal parts with additional Bīng Piàn

Péng Shā clears Heat-toxin from the eyes and removes corneal opacities, while Lú Gān Shí (Calamine) astringes dampness, clears Heat, and brightens the eyes. Together they form a classic ophthalmological pair that addresses both the Heat causing eye inflammation and the corneal clouding that results from it.

When to use: Acute conjunctivitis with redness and swelling, superficial corneal opacities (nebulae), and pterygium. Used together in eye-drop powder preparations like Bái Lóng Dān.

Xiong Huang Péng Shā 2 qián : Xióng Huáng 3 qián (2:3)

Péng Shā clears Heat-toxin with its cool, sweet-salty nature, while Xióng Huáng (Realgar) is warm, acrid, and powerfully toxic to pathogenic organisms and parasites. Together they provide a broad-spectrum antimicrobial and anti-toxin effect for topical treatment of stubborn oral infections, combining Heat-clearing with toxin-killing.

When to use: Oral thrush (goose-mouth sores) in infants, stubborn oral infections, and toxic sores that resist simpler treatments. This pair appears in Sì Bǎo Dān (Four Treasures Elixir) from the Yáng Yī Dà Quán.

Key Formulas

These well-known formulas feature Peng Sha in a prominent role

Yu Yao Shi 玉鑰匙 King

Yù Yuè Shi (Jade Key) from the Sān Yīn Fāng is a classical throat powder for severe Wind-Heat throat obstruction (缠喉风) and throat blockage. Péng Shā serves as a leading ingredient, combined with Xiāo Shí, Bīng Piàn, and Jiāng Cán, blown directly into the throat to clear Heat, dissolve Phlegm, and relieve the obstruction. This formula exemplifies Péng Shā's role in emergency throat conditions.

Bing Peng San 冰硼散 Deputy

Bīng Péng Sǎn (Borneol and Borax Powder) from the Wài Kē Zhèng Zōng is the most iconic formula containing Péng Shā. Used for sore throat, mouth ulcers, and gum pain caused by Heat-toxin, this formula showcases Péng Shā's core external-use action of clearing Heat-toxin and preventing tissue putrefaction. Péng Shā serves as Deputy alongside Xuán Míng Fěn, supporting the King herb Bīng Piàn in clearing Heat, reducing swelling, and stopping pain.

Comparable Ingredients

These ingredients have overlapping uses — here's how to tell them apart

Peng Sha vs Ming Fan

Both Péng Shā and Míng Fán (Alum) are mineral substances used topically for throat and mouth conditions, and both clear Heat-toxin and prevent tissue putrefaction. However, Míng Fán is sour and astringent, making it more drying and better suited for conditions with excessive dampness or oozing (weeping sores, chronic damp lesions). Péng Shā is sweet-salty and cool, making it gentler and better for acute Heat-toxin conditions with swelling and pain. Míng Fán dries and constrains; Péng Shā clears and softens.

Peng Sha vs Qing Dai

Both Péng Shā and Qīng Dài (Indigo Naturalis) are used topically for mouth ulcers, throat inflammation, and oral sores, and both clear Heat-toxin. However, Qīng Dài also cools the Blood and is better for conditions where Blood-Heat is prominent (such as bleeding gums or red, inflamed skin). Péng Shā's salty taste gives it the additional ability to soften hardness and dissolve Phlegm, making it more appropriate when swelling, thick Phlegm, or hard tissue is a key feature.

Common Substitutes & Adulterants

Related species and common adulterations to be aware of when sourcing Peng Sha

Peng Sha in its crystalline form may superficially resemble Ming Fan (alum, potassium aluminium sulfate), as both appear as translucent white crystalline mineral substances. They can be distinguished by taste (borax is salty then sweet; alum is strongly astringent and sour) and the combustion test (borax puffs up then melts into a glass bead; alum liquefies and froths). Industrial-grade borax may be substituted for pharmaceutical-grade borax. Industrial borax may contain higher levels of impurities including heavy metals and should not be used medicinally. Only refined, pharmaceutical-grade borax (精制硼砂) meeting pharmacopoeia standards should be used. Synthetic sodium tetraborate is chemically identical to the natural mineral and is sometimes used as a substitute.

Educational content — always consult a qualified healthcare provider or TCM practitioner before using any ingredient.

Toxicity Classification

Classical Chinese pharmacopoeia toxicity rating for Peng Sha

Slightly toxic

The active component of Peng Sha is sodium tetraborate (Na₂B₄O₇·10H₂O). Boron compounds have dose-dependent toxicity. The adult toxic dose for oral ingestion is reported as 1 to 3 grams, with the lethal dose estimated at 15 grams for adults and 2 to 3 grams for infants. In animal studies (mouse), the intraperitoneal LD50 is approximately 2384 mg/kg, and the oral LD50 via gastric lavage is approximately 2454 mg/kg. Acute borax poisoning symptoms include nausea, vomiting, diarrhoea, skin rash (erythema), circulatory collapse, shock, and coma. Chronic exposure causes cumulative toxicity affecting the gastrointestinal tract, kidneys, and reproductive system. In animal models, high-dose chronic exposure causes testicular atrophy and developmental toxicity. Safety in medicinal use depends on: (1) using very small internal doses (1.5 to 3g maximum) only in pill or powder form, never as a decoction; (2) preferring external application where possible; (3) strictly limiting the duration of internal use; (4) avoiding use in patients with impaired liver or kidney function. The calcined form (Duan Peng Sha) has enhanced astringent properties and is primarily used for external application on weeping lesions.

Contraindications

Situations where Peng Sha should not be used or requires extra caution

Avoid

Pregnancy. Borax is classified as toxic to reproduction in the EU CLP regulation. Animal studies show dose-dependent developmental toxicity and testicular effects at high doses. Internal use during pregnancy is strictly prohibited.

Avoid

Yin deficiency with dryness and fluid depletion. The classical text Ben Cao Hui Yan warns against use when there is Yin deficiency with exhausted fluids, marrow depletion, and Lung atrophy with Heat, as the salty and draining nature of borax can further damage Yin and fluids.

Avoid

Liver or kidney impairment. Borax (sodium tetraborate) is renally excreted, and accumulation is possible in patients with impaired kidney function. Sources note that patients with liver or kidney insufficiency should avoid use.

Avoid

Long-term internal use. Borax has cumulative toxicity when taken orally over prolonged periods. As the Ben Cao Jing Shu states, this is a substance for temporary use, not a medicine for prolonged administration.

Caution

Constitutionally weak or deficient patients. Borax is a draining, clearing substance suited only for excess-type Heat conditions. Use in deficiency patterns may further deplete the body.

Caution

Salt-restricted diets. Borax is a sodium-containing mineral salt. Patients on sodium-restricted diets (hypertension, heart failure, kidney disease) should exercise caution even with topical use if there is potential for systemic absorption.

Special Populations

Important considerations for pregnancy, breastfeeding, and pediatric use

Pregnancy

Contraindicated during pregnancy. In the EU, boric acid and sodium borates are classified as toxic to reproduction under Category 1B. Animal studies demonstrate that high-dose boron exposure causes developmental toxicity in rats, including skeletal abnormalities at doses above 9.6 mg B/kg body weight per day. In mice, very high single doses of boric acid on the first day of pregnancy prevented embryo development. Although epidemiological studies in humans have not confirmed these findings at occupational exposure levels, the known animal developmental toxicity and the cumulative nature of boron in the body make internal use of Peng Sha during pregnancy absolutely contraindicated. External application to small, intact skin areas carries lower risk but should still be avoided during pregnancy as a precaution.

Breastfeeding

Borax should be avoided during breastfeeding for internal use. Boron compounds are readily absorbed and distributed systemically, and are excreted renally. While data on transfer into breast milk is limited, the known systemic toxicity and cumulative nature of boron compounds, combined with the much lower toxic threshold in infants (lethal dose estimated at only 2 to 3 grams), makes internal administration during breastfeeding inadvisable. External application to areas distant from the breast may be considered with caution for short-term use under practitioner supervision.

Children

Peng Sha should be used with extreme caution in children. The lethal dose of borax in infants is reported to be only 2 to 3 grams, far lower than in adults. Internal use in young children is generally avoided. Topical application for oral thrush (goose-mouth sores) in infants is a traditional use described in classical formulas such as Si Bao Dan, but must be applied in very small amounts and for very short periods, with careful attention not to allow excessive swallowing. Any internal use in children must be under strict practitioner supervision with significantly reduced dosage proportional to body weight.

Drug Interactions

If you are taking pharmaceutical medications, be aware of these potential interactions with Peng Sha

There are no extensively documented herb-drug interactions specific to Peng Sha in TCM pharmacological literature. However, based on its known pharmacological properties, the following considerations apply:

Sodium-containing medications: Borax is a sodium salt. Concurrent use with other sodium-containing drugs may compound sodium loading, relevant for patients on sodium-restricted regimens for hypertension or heart failure.
Nephrotoxic drugs: Since boron is renally excreted, concurrent use with nephrotoxic medications (aminoglycoside antibiotics, NSAIDs, certain chemotherapeutics) may increase the risk of boron accumulation and toxicity.
Antiepileptic drugs: Historical clinical use of borax for epilepsy involved co-administration with phenytoin. If borax is used concurrently with anticonvulsants, dose adjustments and monitoring may be necessary. Borax should not be abruptly substituted for conventional antiepileptic medications.

Dietary Advice

Foods and dietary considerations when taking Peng Sha

When using Peng Sha internally (under practitioner supervision), avoid excessively salty foods to prevent additional sodium loading. Avoid cold, raw foods that may further burden the Stomach. Avoid alcohol, which can increase gastrointestinal irritation and potentially enhance borax absorption. Adequate water intake is advisable to support renal clearance of boron.

Botanical Description

Physical characteristics and morphology of the Peng Sha source mineral

Peng Sha (硼砂) is not a plant-derived herb but a naturally occurring mineral. It is a borate mineral belonging to the monoclinic crystal system, with the chemical formula Na₂B₄O₇·10H₂O (hydrated sodium tetraborate, molecular weight 381.37). Individual crystals typically form short columnar or plate-like shapes. In aggregate form, they appear as clusters, granules, or earthy masses.

The mineral is colourless to white, sometimes with faint grey, yellow, blue, or green tints, and has a glassy or oily lustre. It is semi-transparent to opaque, brittle, with a hardness of 2 to 2.5 on the Mohs scale and a specific gravity of 1.69 to 1.72. It has a mildly salty then sweet taste with a cooling sensation. Borax dissolves readily in water (especially hot water) and glycerol. When left in open air, transparent crystals gradually weather into an opaque white powder.

Borax is a chemical precipitate found in dried-up salt lakes containing boron. It forms in arid, evaporitic lake-bed environments, particularly in high-altitude plateaus and desert basins. The medicinal form is a refined crystalline product obtained by dissolving the raw mineral ore in boiling water, filtering, cooling, and collecting the resulting crystals.

Sourcing & Harvesting

Where Peng Sha is sourced, when it's harvested or collected, and how to assess quality

Harvesting season

Mineral borax ore is typically mined from August to November, when the dry season in salt lake regions makes extraction easiest. Some sources indicate it can be collected year-round.

Primary growing regions

Peng Sha is primarily produced in Qinghai Province (particularly the Qaidam Basin) and Tibet (especially the Black River area and Ali Prefecture). These high-altitude, arid salt lake regions represent the traditional prime production areas. Additional production comes from Yunnan, Xinjiang, Sichuan, Shaanxi, and Gansu provinces. The mineral forms naturally as an evaporitic chemical deposit in dried boron-containing salt lakes in these remote western regions of China.

Quality indicators

Good quality Peng Sha appears as colourless, transparent or white semi-transparent crystalline pieces with a glassy lustre. The crystals should be light in weight, brittle, and easily broken. It should dissolve readily in water and have a mildly salty taste followed by a slightly sweet, cooling sensation. Avoid specimens that have become completely opaque white powder (indicating excessive weathering and potential loss of potency). The best grade is described in classical sources as being white and transparent (以色白、透明者为佳). When heated, authentic borax first swells and puffs up like cotton, then melts into a transparent glass-like bead. This combustion test is a traditional quality verification method.

Classical Texts

Key passages from the classical Chinese medical texts that describe Peng Sha and its therapeutic uses

Ben Cao Gang Mu (《本草纲目》) — Li Shizhen

Original: 硼砂，味甘微咸而气凉，色白而质轻，故能去胸膈上焦之热。《素问》云，热淫于内，治以咸寒，以甘缓之是也。其性能柔五金而去垢腻，故治噎膈积聚，骨哽结核。恶肉阴溃用之者，取其柔物也；治痰热，眼目障翳用之者，取其去垢也。

Translation: Borax is sweet, slightly salty in flavour and cool in nature, white in colour and light in substance. Therefore it can clear Heat from the upper body and chest. The Su Wen says: 'When Heat is excessive internally, treat with salty-cold, and moderate with sweet.' Its nature can soften metals and remove grime, thus it treats oesophageal obstruction and accumulations, bone lodged in the throat, and hard lumps. For putrid flesh and genital ulcers, it is used for its softening property; for Phlegm-Heat and eye obstructions, it is used for its ability to remove turbidity.

Ben Cao Jing Shu (《本草经疏》)

Original: 硼砂，色白而体轻，能解上焦胸膈肺分之痰热。辛能散，苦能泄，咸能软，故主消痰，止嗽，喉痹及破症结也。其性柔五金，去垢腻，克削为用，消散为能，宜攻有余，难施不足，此暂用之药，非久服之剂。

Translation: Borax is white in colour and light in substance, able to resolve Phlegm-Heat in the upper body, chest, and Lung region. Its acrid quality disperses, its bitter quality drains, its salty quality softens. Thus it resolves Phlegm, stops cough, and treats throat obstruction and masses. Its nature softens metals and removes grime: it works by cutting and dissolving. It is suited for attacking excess, not for supplementing deficiency. This is a medicine for temporary use, not for prolonged administration.

Ben Cao Hui Yan (《本草汇言》) — Ni Zhumo

Original: 阴虚津燥，髓竭营枯，而成肺痿热胀，痹闷不通诸候，法当禁用。

Translation: In cases of Yin deficiency with dry fluids, exhausted marrow and depleted Blood, manifesting as Lung atrophy with Heat distension, or blocked and oppressive obstruction, [borax] must be prohibited.

Ri Hua Zi Ben Cao (《日华子本草》)

Original: 消痰止嗽，破症结喉痹。

Translation: Resolves Phlegm and stops cough, breaks up masses and treats throat obstruction.

Historical Context

The history and evolution of Peng Sha's use in Chinese medicine over the centuries

Peng Sha first appeared in the Chinese medical literature in the Ri Hua Zi Ben Cao (日华子本草), a Tang Dynasty materia medica text, where its Phlegm-resolving and throat-clearing actions were initially recorded. The herb's alternative names include Peng Sha (蓬砂), Peng Sha (鹏砂), and Yue Shi (月石, "Moon Stone"), the last name referring to its pale, translucent, moon-like appearance. The crystal formations collected on ropes during processing were called "Moon Stone Pendants" (月石坠), while those collected at the bottom of vats were called "Moon Stone Blocks" (月石块).

Li Shizhen's Ben Cao Gang Mu (16th century) significantly expanded the understanding of borax, linking its therapeutic actions to classical Su Wen theory about treating internal Heat with salty-cold substances. He was the first to systematically explain its mechanism: its ability to "soften metals and remove grime" explained its clinical effects on throat obstruction, eye cloudiness, and dissolving accumulations. The Ben Cao Jing Shu further refined this understanding by noting explicitly that borax is suited only for attacking excess patterns and must not be used for deficiency. This distinction was clinically important as it separated borax from gentler Phlegm-resolving herbs.

Borax became a cornerstone ingredient in several famous external-application formulas, most notably Bing Peng San (Ice-Borax Powder) from Chen Shigong's Wai Ke Zheng Zong (《外科正宗》, 1617), which combined borax with Bing Pian (borneol), Xuan Ming Fen, and Zhu Sha for throat and mouth sores. This formula remains widely used today as a patent medicine. In modern times, borax has come under regulatory scrutiny due to its systemic toxicity, and its use as a food additive is banned in many countries. Its medicinal use continues primarily as a topical agent.

Modern Research

3 published studies investigating the pharmacological effects or clinical outcomes of Peng Sha

Review: Effects of boron compounds on human reproduction (2020)

Bolt HM, Duydu Y, Basaran N, Golka K. Effects of boron compounds on human reproduction. Archives of Toxicology. 2020; 94: 717-724.

This comprehensive review examined animal and human epidemiological data on boron reproductive toxicity. In animal studies, high-dose boron caused testicular toxicity and developmental effects. However, epidemiological studies in highly exposed human populations (boron miners in Turkey and China) found no clear evidence of reproductive harm, even under heavy occupational exposure. The authors concluded that the dose levels causing harm in animals are far higher than what humans encounter.

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Epidemiological study: Reproductive toxicity and boron exposure in Turkey (2011)

Duydu Y, Basaran N, Üstündağ A, Aydın S, Undeger U, Ataman OY, et al. Reproductive toxicity parameters and biological monitoring in occupationally and environmentally boron-exposed persons in Bandirma, Turkey. Archives of Toxicology. 2011; 85(6): 589-600.

This study investigated reproductive effects in workers at a boric acid production plant in Bandirma, Turkey. Despite high daily boron exposure levels, no unfavourable effects on sperm quality parameters, FSH, LH, or testosterone levels were found. The authors concluded that dose levels associated with reproductive toxicity in animals are far from reachable in normal human occupational exposure.

PubMed

Review: General, reproductive, developmental, and endocrine toxicity of boronated compounds (1998)

Fail PA, Chapin RE, Price CJ, Heindel JJ. General, reproductive, developmental, and endocrine toxicity of boronated compounds. Reproductive Toxicology. 1998; 12(1): 1-18.

This review established key toxicological parameters for boron compounds. In rats, testicular effects occurred at approximately 26 mg boron equivalents per kg body weight per day, and the no-observed-adverse-effect level (NOAEL) for fetal development was 9.6 mg/kg. Boron compounds were found to be non-carcinogenic and non-mutagenic. With a safety factor of 30, the authors concluded that humans are not at significant risk of reproductive failure from environmental boron exposure.

PubMed

Research on individual TCM herbs is growing but still limited by Western clinical trial standards. These studies provide emerging evidence and should be considered alongside practitioner expertise.