What patterns does Meng Shi address?

Meng Shi addresses these TCM patterns of disharmony: Phlegm-Heat in the Lungs, Phlegm-Fire harassing the Heart, Blood Stagnation.

What conditions is Meng Shi used for?

Meng Shi is commonly used for: Epilepsy, Chronic Bronchitis, Asthma, Schizophrenia, Whooping Cough, Constipation, Insomnia. A TCM practitioner would consider this herb when these conditions arise from the specific patterns it addresses.

Ingredient Mineral (矿物 kuàng wù)

Meng Shi

Q: What are the TCM actions of Meng Shi?

The TCM actions of Meng Shi include: Descends Qi and Transforms Phlegm, Calms the Liver and Stops Convulsions, Promotes Digestion and Resolves Food Stagnation.

Chlorite schist / Mica schist · 礞石

Chlorite Schist / Mica Schist (Biotite Schist) · Lapis Micae seu Chloriti

Also known as: Qing Meng Shi (青礞石)

Meng Shi (Chlorite schist / Mica schist) plant

Images shown are for educational purposes only

Méng Shí is a mineral medicine (chlorite or mica schist) used primarily for difficult, stubborn phlegm that ordinary remedies cannot clear. It is especially employed when thick phlegm causes persistent coughing with hard-to-expectorate sputum, or when phlegm accumulation in the body triggers seizures, convulsions, or mental agitation. Because of its powerful action, it is typically reserved for acute, excess conditions and is not suitable for prolonged use or for people with weak digestion.

Category Herbs that cool and transform Phlegm-Heat (清化热痰药)

Therapeutic focus Respiratory Health Neurological Health Digestive Health

TCM Properties

Temperature

Neutral

Taste

Sweet (甘 gān), Salty (咸 xián)

Channels entered

Lungs, Liver

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 Meng Shi does in the body, explained in both everyday and TCM terms

Therapeutic focus

In practical terms, Meng Shi is primarily used to support these areas of health:

Respiratory Health Neurological Health Digestive Health

TCM Actions

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

Descends Qi and Transforms Phlegm Calms the Liver and Stops Convulsions Promotes Digestion and Resolves Food Stagnation

How these actions work

'Descends Qi and expels Phlegm' is the primary action of Méng Shí. As a heavy mineral, it has a powerful downward-bearing nature that physically drags stubborn, thick, sticky phlegm downward and out of the body. This is not for ordinary phlegm that clears easily with a cough. It targets what practitioners call 'old phlegm' or 'stubborn phlegm' (顽痰, 老痰) — thick, gluey accumulations that have lodged deep in the chest and digestive tract and refuse to budge. When this kind of phlegm blocks the lungs, it causes severe coughing with thick sputum that is difficult to expectorate and laboured breathing. The salty taste softens hardened accumulations while the heavy mineral quality drives everything downward.

'Calms the Liver and settles convulsions' refers to the herb's ability to anchor rising Liver activity. When hot phlegm combines with Liver Wind, it can produce seizures, convulsions, manic behaviour, or palpitations. The heavy, sinking nature of Méng Shí pulls this turbulent upward movement back down, calming the spirit and stopping spasms. Classical texts describe it as a key medicine for phlegm-related epilepsy and childhood convulsions due to phlegm-heat.

'Resolves food stagnation' reflects the herb's secondary use for chronic, stubborn food accumulations that have not resolved over a long period. The Jiā Yòu Běn Cǎo (嘉佑本草) specifically noted its use for food masses stuck in the organs, including in women with long-standing abdominal masses from food stagnation.

Patterns Addressed

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

Why Meng Shi addresses this pattern

When Heat and Phlegm combine in the Lungs, they produce thick, sticky, yellow sputum that is extremely difficult to cough up. The phlegm becomes 'cooked' by internal heat into a dense, gluey substance that ordinary expectorants cannot dislodge. Méng Shí's salty taste softens and dissolves hardened phlegm accumulations, while its heavy, downward-bearing mineral nature physically drives this stubborn material out of the airways. It enters the Lung channel directly and acts as a powerful descending force, redirecting the abnormally rising Lung Qi that manifests as cough and wheezing back downward. This herb is specifically indicated when the phlegm has been present for a long time and has become what practitioners call 'old phlegm' (老痰).

A practitioner would look for one or more of these signs

Cough With Thin Yellow Sputum

Thick, sticky, difficult-to-expectorate sputum

Wheezing

Wheezing and chest oppression from phlegm obstruction

Chest Stiffness

Sensation of fullness and blockage in the chest

Why Meng Shi addresses this pattern

When hot phlegm accumulates and rises to disturb the Heart and cloud the mind's openings, it produces mental agitation, mania, seizures, or loss of consciousness. The pathomechanism involves Phlegm and Fire mutually reinforcing each other — Fire condenses fluids into Phlegm, and Phlegm traps Heat, creating a vicious cycle. Méng Shí addresses this pattern through its heavy, sinking nature that pulls the turbulent phlegm-fire complex downward, away from the Heart and brain. Its salty flavour breaks apart hardened phlegm masses, while its Liver-calming action settles the internal Wind that often accompanies this pattern. The Ben Cao Gang Mu describes it as a 'sacred medicine for treating convulsions and resolving phlegm.'

A practitioner would look for one or more of these signs

Seizures

Epileptic seizures or convulsions from phlegm-heat

Mania

Manic or agitated behaviour, delirium

Palpitations

Severe palpitations with restlessness

Sputum

Copious thick phlegm with mental disturbance

Commonly Used For

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

Arises from: Phlegm-Fire harassing the Heart

TCM Interpretation

In TCM, epilepsy is most commonly understood as a condition involving the accumulation of Phlegm that periodically rises to obstruct the Heart's openings and disturb the spirit (Shén). When this Phlegm is combined with Heat or Fire, it becomes especially virulent and difficult to clear. The Phlegm may have accumulated over years, becoming what is called 'old Phlegm' or 'stubborn Phlegm,' deeply lodged in the body's channels. During an episode, this Phlegm-Fire complex surges upward, clouding consciousness, triggering convulsions, and causing loss of awareness. The Liver channel is also implicated, as Liver Wind stirring internally combines with Phlegm to produce the convulsive movements.

Why Meng Shi Helps

Méng Shí is specifically suited for phlegm-heat type epilepsy because of its unique combination of properties. Its salty taste softens and dissolves the hardened, sticky phlegm that ordinary expectorants cannot touch. Its heavy mineral nature provides a powerful anchoring and descending force that pulls the turbulent Phlegm-Fire downward, away from the brain and Heart. It also calms the Liver, helping to settle the internal Wind that drives the convulsive aspect of seizures. Classical texts specifically call Méng Shí 'a sacred medicine for convulsions and resolving phlegm.' Modern clinical research has shown that preparations containing Méng Shí can suppress epileptiform discharges and reduce neuronal inflammation in the hippocampus.

Arises from: Phlegm-Heat in the Lungs

TCM Interpretation

Chronic bronchitis with persistent productive cough is understood in TCM as a condition where Phlegm has accumulated in the Lungs over a long period. When this Phlegm transforms with Heat, it becomes thick, yellow, and extremely adhesive, clinging to the airways and resisting expectoration. The Lung's normal function of descending and dispersing Qi becomes impaired, leading to coughing, wheezing, and a sensation of chest oppression. Over time, the Phlegm 'nests' in the folds of the airways, becoming what classical texts describe as old or stubborn Phlegm.

Why Meng Shi Helps

Méng Shí enters the Lung channel and has a uniquely powerful descending action that can dislodge even deeply lodged, chronic phlegm accumulations. Where milder expectorants like Bàn Xià or Chén Pí may only address superficial or fresh phlegm, Méng Shí's heavy mineral nature and salty taste allow it to soften and sweep away old, adhesive phlegm from the deep recesses of the respiratory tract. It redirects the abnormally rising Lung Qi back downward, relieving cough and wheezing. It is typically combined with other herbs that clear Heat (like Huáng Qín) and direct Qi downward (like Chén Xiāng) for this application, as exemplified in its flagship formula Gǔn Tán Wán.

Also commonly used for

Asthma

Phlegm-heat type with thick yellow sputum and wheezing

Schizophrenia

Used within formulas for manic episodes attributed to phlegm-fire

Whooping Cough

Classical use documented in regional formularies

Constipation

Accompanying phlegm-heat conditions, often via Gun Tan Wan

Insomnia

Stubborn insomnia due to phlegm-fire harassing the Heart

Ingredient Properties

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

Temperature

Neutral

Taste

Sweet (甘 gān), Salty (咸 xián)

Channels Entered

Lungs Liver

Parts Used

Mineral (矿物 kuàng wù)

Dosage & Preparation

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

Standard dosage

6-10g in decoction; 1.5-3g when taken as powder or in pills

Maximum dosage

Up to 15g in decoction (with cloth wrapping) for acute excess conditions; more commonly used at 1.5-3g in pill or powder form. Do not exceed 15g.

Dosage notes

Meng Shi is most commonly used in pill or powder form at 1.5-3g per dose, as this allows for more precise dosing of this potent mineral. When used in decoction, 6-10g is the standard range, and it must be wrapped in cloth to prevent sediment in the liquid. Higher decoction doses up to 10-15g may be used for acute stubborn Phlegm conditions, but only under practitioner supervision and for short courses. This herb is intended for acute excess patterns only and should not be taken long-term. The calcined form (Duan Meng Shi) is more readily absorbed and is preferred for clinical use over the raw mineral.

Preparation

Meng Shi is a mineral that requires special decoction handling. When used in decoction, it should be wrapped in cloth (包煎, bao jian) to prevent gritty sediment in the liquid, and decocted first (先煎, xian jian) for 30 minutes before adding other herbs. More commonly, it is used in pre-made pill or powder form rather than decoction. The standard processing method (calcination with niter) involves mixing crushed Meng Shi with an equal weight of Xiao Shi (niter/saltpetre), placing the mixture in a crucible, and calcining over high charcoal fire until the niter is fully consumed and the stone turns golden in colour. The product is then ground to fine powder by water-levigation (水飞, shui fei) to remove residual niter.

Processing Methods

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

Processing method

The raw mineral is crushed into small pieces, mixed with an equal weight of Flame Nitre (焰硝, Niter/potassium nitrate), placed in a sealed clay crucible, and calcined over strong charcoal fire until the nitre is consumed and the stone turns golden-yellow in colour. After cooling, it is ground into a fine powder and levigated (水飞) to remove residual nitre toxicity.

How it changes properties

Calcination with nitre dramatically activates the mineral's properties. Raw Méng Shí is dense and inert, and its therapeutic potential is largely locked within the stone matrix. After calcination, the texture becomes soft and crumbly, making it much easier to grind into fine powder for absorption. The calcined form has a far stronger ability to dislodge and expel stubborn phlegm. As the classical text Běn Cǎo Wèn Dá states: without calcination, the stone quality does not transform, the medicinal nature is not activated, and the toxicity is not dispersed. The temperature and channel entry remain essentially unchanged.

When to use this form

The calcined form is the standard clinical form used in virtually all prescriptions. Raw Méng Shí is rarely used because its medicinal properties are poorly bioavailable. Whenever Méng Shí appears in a formula — such as Gǔn Tán Wán — it refers to the calcined form.

Common Ingredient Pairs

These ingredients are traditionally combined with Meng Shi for enhanced therapeutic effect

Da Huang Méng Shí 30g : Dà Huáng 240g (as in Gǔn Tán Wán, where Dà Huáng is used in much larger quantity)

Méng Shí dislodges stubborn, sticky old phlegm from the digestive tract and airways, while Dà Huáng opens the downward pathway by purging accumulated heat and waste through the bowels. Together, they create a powerful one-two punch: Méng Shí loosens the deeply lodged phlegm that clings to the intestinal walls, and Dà Huáng flushes it out of the body. Neither alone is as effective — Méng Shí without Dà Huáng may loosen phlegm but lacks a clear exit route, while Dà Huáng alone cannot break apart the gluey phlegm.

When to use: Used when stubborn phlegm-heat causes mental disturbance, mania, or severe constipation with thick yellow tongue coating and forceful slippery pulse.

Chen Xiang Méng Shí 30g : Chén Xiāng 15g (as in Gǔn Tán Wán)

Méng Shí provides heavy downward force to expel stubborn phlegm, while Chén Xiāng (Agarwood) smoothly directs Qi downward and prevents the mineral from irritating the intestinal lining. Classical commentary explains that Chén Xiāng ensures Méng Shí does not stick to the intestinal walls, while also drawing Qi back down to its root in the Kidneys. The pairing embodies the principle 'to treat phlegm, first regulate the Qi.'

When to use: Used when old phlegm blocks the middle and upper body with chest oppression, wheezing, and Qi counterflow.

Huang Qin Méng Shí 30g : Huáng Qín 240g (as in Gǔn Tán Wán, where Huáng Qín is the dominant herb by weight)

Méng Shí attacks the phlegm itself, while Huáng Qín clears the Heat that is the root cause of phlegm formation. Together, they address both the branch (accumulated phlegm) and the root (excess Heat) of phlegm-heat conditions. Huáng Qín's bitter, cold nature dries dampness and clears fire from the upper burner, preventing new phlegm from forming even as Méng Shí drives out the old.

When to use: Used for phlegm-fire conditions with signs of excess heat: yellow tongue coating, red tongue, irritability, thick yellow sputum.

Key Formulas

These well-known formulas feature Meng Shi in a prominent role

Gun Tan Wan 滚痰丸 Assistant

Gǔn Tán Wán (Vaporize Phlegm Pill) is the single most important formula associated with Méng Shí and the one that best showcases its unique ability to expel deeply lodged old phlegm. Created by Wáng Yǐn Jūn (recorded in Dān Xī Xīn Fǎ Fù Yú), this four-herb formula pairs calcined Méng Shí with Dà Huáng, Huáng Qín, and Chén Xiāng to create a powerful phlegm-scouring combination. Although Méng Shí serves as Assistant by weight (30g versus 240g each for Dà Huáng and Huáng Qín), classical commentary states it is the herb that gives the formula its name — its fierce, scouring nature sweeps through the intestinal folds to dislodge phlegm that no other herb can reach. Clinically used for epilepsy, mania, stubborn insomnia, and various 'strange diseases' attributed to phlegm-fire.

Comparable Ingredients

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

Meng Shi vs Tian Zhu Huang

Both clear hot phlegm and are used for convulsions, but Tiān Zhú Huáng (Bamboo Sugar/Siliceous Secretion of Bamboo) is much gentler and is suited for paediatric use and milder phlegm-heat conditions. Méng Shí is far more powerful and specifically targets deeply lodged, chronic 'old phlegm' that Tiān Zhú Huáng cannot dislodge. Tiān Zhú Huáng also clears Heart Heat and calms fright more gently, making it appropriate for children with febrile convulsions, while Méng Shí is reserved for severe, excess-type presentations.

Meng Shi vs Zhu Ling

Both address hot phlegm, but Zhú Lì (Bamboo Sap) is a liquid that clears heat and dissolves phlegm through its cool, slippery nature — it is best for phlegm-heat causing cough or stroke-related loss of speech where there is phlegm blocking the throat. Méng Shí is a heavy mineral that works by physically sinking and breaking apart hardened, chronic phlegm masses. Zhú Lì is milder and can be used in weaker patients, while Méng Shí is strictly for strong, excess constitutions.

Meng Shi vs Hai Fu Shi

Both are mineral substances that clear phlegm-heat, but Hǎi Fú Shí (Pumice) is much lighter and works primarily by softening and dissolving phlegm through its salty taste, also promoting urination. It is gentler and lacks the powerful downward-driving force of Méng Shí. Méng Shí is heavier, more aggressive, and specifically targets old, stubborn phlegm and Liver-related convulsions — applications where Hǎi Fú Shí would be too mild.

Common Substitutes & Adulterants

Related species and common adulterations to be aware of when sourcing Meng Shi

Qing Meng Shi (chlorite schist) and Jin Meng Shi (mica schist) are often confused or used interchangeably despite having different mineral compositions. Classical texts originally referred only to Qing Meng Shi; the name 'Jin Meng Shi' is a later distinction. The Chinese Pharmacopoeia now lists them as separate entries. The key distinguishing features are: Qing Meng Shi is grey-green to black-green with star-like sparkles on the cross-section, while Jin Meng Shi is brownish-yellow with bright golden lustre. Common non-medicinal rocks of similar appearance may be mixed in as adulterants, so it is important to verify the characteristic foliated structure and lustre. Pieces without the distinctive star-point sparkle in the cross-section were considered unsuitable for medicinal use by Li Shizhen.

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

Toxicity Classification

Classical Chinese pharmacopoeia toxicity rating for Meng Shi

Non-toxic

Meng Shi is classified as non-toxic in classical sources. The Ben Cao Gang Mu, Yi Xue Ru Men, and Ben Cao Jing Shu all describe it as having no inherent toxicity (无毒). However, its powerful downward-draining and Phlegm-expelling action makes it harsh on the digestive system, and misuse in deficient patients can cause serious harm. The classical record of a patient dying after receiving Meng Shi for a deficiency condition reflects not chemical toxicity but the dangerous consequences of using a strongly draining substance on someone too weak to tolerate it. Processing by calcination with niter (Xiao Shi) tempers its properties and makes it safer and more effective for clinical use.

Contraindications

Situations where Meng Shi should not be used or requires extra caution

Avoid

Pregnancy. Meng Shi is a heavy, downward-draining mineral substance that can adversely affect the fetus. Classical texts explicitly state that pregnant women should not use it.

Avoid

Spleen and Stomach deficiency with weakness. Meng Shi's heavy, descending nature and harsh draining action can further damage weak digestion. As the Ben Cao Cong Xin states, those with Qi weakness and Blood deficiency should strictly avoid it.

Caution

Yin deficiency with dry Phlegm. Meng Shi is indicated only for excess-type Phlegm-Heat. In Yin-deficient patients where dryness rather than dampness produces the phlegm, this harsh draining herb will worsen the condition.

Caution

Chronic illness with general debility. Li Shizhen warned against prolonged use in weak patients, citing a case where a physician administered Meng Shi to an elderly patient with a severe deficiency pattern, resulting in death. The herb is only suitable for acute, excess conditions.

Caution

Pediatric slow convulsions (man jing) from Spleen deficiency. In children with deficiency-type convulsions, Meng Shi's draining nature is inappropriate without careful supporting herbs. Yang Shiying noted it should be combined with Mu Xiang (Aucklandia) in such cases.

Special Populations

Important considerations for pregnancy, breastfeeding, and pediatric use

Pregnancy

Contraindicated during pregnancy. Meng Shi is a heavy mineral with a strong downward-draining and purging action that could stimulate uterine activity or harm the fetus. Multiple classical sources explicitly prohibit its use in pregnant women, and this prohibition is maintained in modern Chinese Pharmacopoeia guidelines for formulas containing Meng Shi (e.g. Gun Tan Wan is labelled as contraindicated in pregnancy).

Breastfeeding

No specific classical or modern safety data exists for Meng Shi use during breastfeeding. Given its mineral nature and harsh draining properties, it is generally considered inadvisable during breastfeeding. If clinical necessity requires its use, it should be limited to the shortest possible course at the lowest effective dose, under practitioner supervision.

Children

Meng Shi has a long history of pediatric use for childhood convulsions (jing feng) and food stagnation with emaciation. However, it is a harsh draining substance and should only be used in children with robust constitutions and clear excess patterns (Phlegm-Heat). It is not appropriate for children with deficiency-type convulsions or weak digestion. Dosages should be significantly reduced from adult levels and the herb should only be used short-term. Yang Shiying recommended always adding Mu Xiang (Aucklandia) to protect the Stomach when using Meng Shi in children with Spleen deficiency patterns.

Drug Interactions

If you are taking pharmaceutical medications, be aware of these potential interactions with Meng Shi

No well-documented pharmacological drug interactions have been established for Meng Shi in peer-reviewed literature. As a mineral primarily composed of hydrous silicates of magnesium, aluminium, and iron, it has the theoretical potential to affect absorption of concurrently administered oral medications through adsorption or chelation in the gastrointestinal tract. Patients taking pharmaceutical medications orally should separate dosing times by at least two hours as a precaution.

Dietary Advice

Foods and dietary considerations when taking Meng Shi

While taking Meng Shi, avoid cold, raw, greasy, and difficult-to-digest foods, as the herb is already harsh on the digestive system. Light, easily digestible foods such as congee and cooked vegetables are preferable. Avoid excessive consumption of rich, fatty, or phlegm-producing foods (dairy, deep-fried food, excessively sweet foods) which would counteract the herb's Phlegm-draining purpose.

Botanical Description

Physical characteristics and morphology of the Meng Shi source mineral

Meng Shi (礞石) is not a plant but a mineral substance. It comes in two main varieties:

Qing Meng Shi (青礞石, Green Meng Shi / Lapis Chloriti): This is chlorite schist, a metamorphic rock primarily composed of chlorite minerals, often in fine scaly or needle-like aggregates. It ranges from green to dark green in colour, with a hardness of 2 to 2.5 on the Mohs scale. It may also contain magnetite, actinolite, and epidote as minor minerals. The rock forms in regions of metamorphic geological activity.

Jin Meng Shi (金礞石, Golden Meng Shi / Lapis Micae Aureus): This is mica schist, composed primarily of mica-family minerals (biotite and muscovite) along with quartz and feldspar. It displays a pronounced foliated (layered) structure and its colour varies depending on mica type: silvery-white if rich in muscovite, or dark brown-black if rich in biotite. Both varieties are soft, brittle, and easily crumbled by hand.

Sourcing & Harvesting

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

Harvesting season

Can be mined year-round. After extraction, impurities such as soil and non-medicinal rock are removed.

Primary growing regions

Qing Meng Shi (green variety): Primarily produced in Hunan, Hubei, Sichuan, Jiangsu, and Zhejiang provinces. Li Shizhen noted that it is found in various mountains north of the Yangtze and considered the material from Xu (盱) Mountain to be the finest. Jin Meng Shi (golden variety): Primarily produced in Henan and Hebei provinces. As a mineral rather than a cultivated herb, Meng Shi does not have the same 'terroir' (dao di yao cai) concept as botanical drugs, but regional geological conditions do affect quality. Production areas include Shandong as well.

Quality indicators

Qing Meng Shi (green variety): Good quality pieces are intact blocks with a greenish-grey or grey-green colour, displaying a subtle pearly lustre. The cross-section should show a clear layered (foliated) structure with visible sparkling star-like points (星点). The material should be soft enough to scratch with a fingernail. Pieces should be free of soil or non-medicinal rock inclusions. After calcination with niter, good quality material turns golden yellow. Jin Meng Shi (golden variety): Good quality pieces are intact blocks with a brownish-yellow colour and bright golden lustre. The material should be brittle and easy to crumble into small flaky, glittering fragments with a greasy feel. It should be free of impurities, with a faint or no odour and a bland taste.

Classical Texts

Key passages from the classical Chinese medical texts that describe Meng Shi and its therapeutic uses

Ben Cao Gang Mu (《本草纲目》, Li Shizhen, Ming Dynasty)

「青礞石，其性下行。肝经风木太过，来制脾土，气不运化，积滞生痰，壅塞上中二焦，变生风热诸病，故宜此药重坠。制以消石，其性疏快，使木平气下，而痰积通利，诸证自除。」

"Green Meng Shi has a downward-moving nature. When the Liver (Wood) becomes excessive and overacts on the Spleen (Earth), Qi movement is disrupted, stagnation accumulates into Phlegm, and the upper and middle Jiao become obstructed, giving rise to various Wind-Heat disorders. Therefore, this heavy, sinking substance is appropriate. When processed with niter (Xiao Shi), its dispersing and expediting nature causes the Liver to settle, Qi to descend, and Phlegm accumulation to pass freely, so all symptoms resolve naturally."

Ben Cao Gang Mu continued

「汤衡《婴孩宝鉴》言礞石乃治惊利痰之圣药，吐痰在水上，以石末糁之，痰即随水而下，则其沉坠之性可知。然止可用之救急，气弱脾虚者，不宜久服。」

"Tang Heng's Ying Hai Bao Jian calls Meng Shi a 'holy medicine for treating fright and expelling Phlegm.' If phlegm is spat onto water and Meng Shi powder is sprinkled on it, the phlegm immediately sinks, demonstrating its heavy, downward-pulling nature. However, it should only be used for emergencies. Those with weak Qi and deficient Spleen should not take it for prolonged periods."

Jia You Ben Cao (《嘉佑本草》, Song Dynasty)

「治食积不消，留滞在脏腑，宿食症块久不瘥，及小儿食积羸瘦，妇人积年食症，攻刺心腹。」

"Treats food stagnation that does not resolve, lodged in the organs, chronic food masses that persist, as well as childhood emaciation from food accumulation, and women's long-standing food masses that cause stabbing pain in the chest and abdomen."

Pin Hui Jing Yao (《品汇精要》, Ming Dynasty)

「坠痰消食。」

"Sinks Phlegm and disperses food [stagnation]."

Historical Context

The history and evolution of Meng Shi's use in Chinese medicine over the centuries

Meng Shi first appeared in the pharmaceutical literature during the Song Dynasty in the Jia You Ben Cao (嘉佑本草, 1060 CE), where it was primarily described for treating food stagnation and abdominal masses. Its use evolved significantly during the Jin-Yuan medical reform period, when physicians began emphasizing its role in treating stubborn Phlegm.

The most famous formula containing Meng Shi is Gun Tan Wan (滚痰丸, "Rolling Phlegm Pill"), attributed to Wang Yingjun (王隐君). This formula combined calcined Meng Shi with Da Huang (rhubarb), Huang Qin (scutellaria), and Chen Xiang (agarwood) to purge stubborn Phlegm-Heat. Wang controversially promoted it as a universal remedy for all phlegm-related diseases, a claim Li Shizhen strongly criticized in the Ben Cao Gang Mu, arguing that using such a harsh draining formula indiscriminately on patients regardless of their constitutional strength was irrational. Li Shizhen also recorded a cautionary case from Zhu Danxi about an elderly patient with sudden blindness (a severe deficiency condition) who was given Meng Shi and died the same night, though Li attributed the death to the physician's error, not the herb itself.

Tang Heng, in his pediatric text Ying Hai Bao Jian (婴孩宝鉴), famously called Meng Shi "a holy medicine for treating fright and expelling Phlegm" and described a vivid demonstration: if phlegm is spat onto water and Meng Shi powder is sprinkled over it, the phlegm sinks immediately, illustrating its powerful downward-pulling nature. Yang Shiying (杨士瀛) further noted that while Meng Shi is effective at expelling Phlegm, "its nature is not what the Stomach favours," recommending that Mu Xiang (Aucklandia) always be added to protect digestion.