Ingredient Animal — secretion (动物分泌物 dòng wù fēn mì wù)

Chan Su

Toad venom · 蟾酥

Bufo bufo gargarizans Cantor; Bufo melanostictus Schneider · Venenum Bufonis

Also known as: Ha Ma Su (蛤蟆酥)

Chan Su is the dried venom secreted by the parotid and skin glands of the Asiatic toad. It is a potent but toxic substance used in Chinese medicine to clear infections, reduce swelling, relieve pain, and revive consciousness. Because of its strong toxicity, it is almost always used in very small doses within prepared pill formulas such as Liu Shen Wan, and should never be taken without professional guidance.

Category Substances for external application Toxin-attacking and insect-killing herbs
Therapeutic focus Pain relief Skin health Throat health Heart health

TCM Properties

Temperature

Warm

Taste

Acrid / Pungent (辛 xīn), Sweet (甘 gān)

Channels entered

Heart

Parts used

Animal — secretion (动物分泌物 dòng wù fēn mì 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 Chan Su does in the body, explained in both everyday and TCM terms

Therapeutic focus

In practical terms, Chan Su is primarily used to support these areas of health:

Pain relief Skin health Throat health Heart health

TCM Actions

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

Relieves toxicity and reduces swelling Alleviates pain Opens the orifices and revives consciousness Expels filth and turbidity

How these actions work

'Relieves toxicity and reduces swelling' is Chan Su's primary action. In TCM, toxic sores (such as boils, abscesses, and carbuncles) arise when Fire toxin accumulates locally. Chan Su's acrid, warm, and strongly penetrating nature allows it to break through this accumulation, disperse the swelling, and push the toxin out. This is why it features prominently in formulas for severe throat infections, skin abscesses, and deep-rooted boils. It can be applied externally or taken internally in tiny doses within pills.

'Alleviates pain' refers to Chan Su's notable ability to numb and relieve pain. This applies to toothache (where a tiny amount is placed directly on the painful tooth), sore throat, and the throbbing pain of abscesses and boils. Modern research has confirmed that its bufadienolide compounds produce a local anesthetic effect comparable to cocaine in potency, explaining its traditional use for pain.

'Opens the orifices and revives consciousness' means Chan Su can be used in emergencies where a person has lost consciousness, particularly from summer-heat stroke or exposure to turbid, filthy environmental pathogens. Its acrid, dispersing nature cuts through the obstruction blocking the sensory orifices (the 'clear orifices' of the head), restoring awareness. It is combined with Musk (She Xiang) and other aromatic substances for this purpose.

'Expels filth and turbidity' relates to its use in acute gastrointestinal crises caused by consuming contaminated food or by summer dampness. When a person develops sudden vomiting, diarrhea, and abdominal cramping from exposure to foul or unclean substances, Chan Su helps disperse the turbid obstruction and restore normal function.

Patterns Addressed

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

Why Chan Su addresses this pattern

When Fire toxin accumulates in the flesh and skin, it produces painful, swollen sores such as boils (ding chuang), carbuncles (yong ju), and abscesses. Chan Su directly attacks this accumulated toxin with its acrid, warm, and powerfully penetrating nature. Its ability to enter the Heart channel is relevant here because the Heart governs the Blood, and Fire toxin in the Blood drives the formation of these lesions. Chan Su disperses the toxic accumulation and reduces the swelling and pain that characterize this pattern.

A practitioner would look for one or more of these signs

Boils

Deep-rooted, painful boils with hot, red swelling

Abscess

Carbuncles and abscesses with severe local pain

Sore Throat

Severely swollen, painful throat that impedes swallowing

Toothache

Intense toothache from dental infection or decay

Commonly Used For

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

Arises from: Fire Toxin generating sores

TCM Interpretation

Severe sore throat with swelling and difficulty swallowing is understood in TCM as Fire toxin flaring upward and accumulating in the throat area. The throat is along the pathway of several channels, and when intense Heat and toxin lodge there, the tissues become red, swollen, and extremely painful. In severe cases (such as what was classically called 'rotten throat scarlet rash' or lan hou dan sha), the tissue may ulcerate. This is a manifestation of virulent Fire toxin that requires strong toxin-clearing treatment.

Why Chan Su Helps

Chan Su's powerful toxin-relieving and swelling-reducing actions target the Fire toxin lodged in the throat. Its acrid nature disperses the accumulation, while its analgesic properties provide rapid pain relief. In the famous formula Liu Shen Wan, Chan Su works alongside Niu Huang (ox gallstone) and Bing Pian (borneol) to clear the toxin and reduce inflammation. This is one of the most well-established traditional uses of Chan Su, documented over centuries in throat-disease treatment.

Also commonly used for

Boils

Deep-rooted boils and carbuncles

Abscess

Skin abscesses and purulent infections

Toothache

Severe dental pain from decay or infection

Scrofula

Scrofula and chronic lymph node swelling

Cancer

Various cancers as adjunctive therapy (modern research)

Ingredient Properties

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

Temperature

Warm

Taste

Acrid / Pungent (辛 xīn), Sweet (甘 gān)

Channels Entered

Heart

Parts Used

Animal — secretion (动物分泌物 dòng wù fēn mì wù)

Dosage & Preparation

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

Standard dosage

0.015-0.03g (internal, in pill or powder form only)

Maximum dosage

Do not exceed 0.03g per dose internally. This is an inherently toxic substance with an extremely narrow therapeutic margin. Any overdose can be fatal.

Dosage notes

Chan Su is NEVER used in decoction form. It is only taken internally in pill (丸) or powder (散) formulations, in which it is combined with other medicinals that help buffer its toxicity. A typical internal dose is 0.015-0.03g per administration. Some sources note doses as small as 2-4 li (approximately 0.006-0.012g) for sensitive patients. When used externally as a plaster, paste, or tincture, the amount is adjusted according to the affected area but must still avoid contact with eyes and broken skin near mucous membranes. Processing with alcohol (酒炙) by soaking crushed Chan Su in rice wine until it forms a paste, then drying, is the standard preparation to moderate toxicity and improve workability. It is a key component of prepared formulas like Liu Shen Wan (六神丸), where the per-dose quantity of Chan Su is carefully calibrated within the pill composition.

Preparation

Chan Su must NEVER be decocted or used in decoction (汤剂). It is only used internally in pill (丸剂) or powder (散剂) form, in carefully measured minute doses. Standard processing (酒炙): crush the raw Chan Su, soak in white rice wine, stir until it forms a thick paste, then dry and grind. This alcohol processing moderates the toxicity and makes the material workable. When making external plasters or tinctures, dissolve in alcohol or mix with oil. Handle with care during preparation: avoid touching eyes or face, and wash hands thoroughly after handling. The powder causes violent sneezing if inhaled.

Processing Methods

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

Processing method

The raw Chan Su is broken into pieces, placed in a ceramic vessel, and soaked in white liquor (bai jiu). The mixture is stirred frequently until it dissolves into a thick paste, which is then dried in a clean, ventilated area and ground into fine powder. The standard ratio is 10 parts Chan Su to 20 parts white liquor.

How it changes properties

Wine processing makes the extremely hard raw material easier to pulverize into fine powder for use in pills and powders. It reduces the irritant effect on operators handling the substance (raw Chan Su powder causes uncontrollable sneezing and can irritate mucous membranes). The thermal nature and channel entry remain unchanged. Research shows that total cardiotonic steroid content may increase slightly after wine processing, potentially enhancing therapeutic potency while the overall toxicity profile becomes more manageable.

When to use this form

This is the standard processed form specified by the Chinese Pharmacopoeia (2010 and later editions). It is used whenever Chan Su is incorporated into pill or powder formulas for internal use, such as Liu Shen Wan. Virtually all clinical internal use of Chan Su employs this wine-processed form.

Common Ingredient Pairs

These ingredients are traditionally combined with Chan Su for enhanced therapeutic effect

Niu Huang
Niu Huang Chan Su is used in very small amounts relative to Niu Huang, approximately 1:3 (Chan Su : Niu Huang)

Niu Huang (ox gallstone) is cool and clears Heart Heat and resolves toxin, while Chan Su is warm and attacks toxin with its acrid, penetrating nature. Together, they create a balanced and powerful toxin-clearing pair where Niu Huang's cooling nature helps moderate Chan Su's warmth and toxicity, while both substances synergize to clear Fire toxin from the throat and skin. This is the core pairing in Liu Shen Wan.

When to use: Severe throat infections with swelling and pain, deep-rooted boils, carbuncles, and other acute Fire toxin conditions.

She Xiang
She Xiang 1:1 (both used in very small doses, typically fractions of a gram)

She Xiang (musk) is an aromatic orifice-opener that powerfully penetrates obstructions. Combined with Chan Su, the two substances work together to open blocked orifices, revive consciousness, and disperse toxic swelling. She Xiang's strong penetrating quality enhances Chan Su's ability to reach deep-seated toxin and helps carry the formula's therapeutic action to the site of disease.

When to use: Loss of consciousness from summer-heat, acute abdominal pain with vomiting and diarrhea from turbid obstruction, and severe toxic swellings where deep penetration is needed.

Xiong Huang
Xiong Huang Xiong Huang 2:1 to Chan Su (e.g. Xiong Huang 6g : Chan Su 3g in classical pill formulas)

Xiong Huang (realgar) is a mineral substance that attacks toxin and kills parasites. Paired with Chan Su, the two create a potent toxin-clearing combination with strong anti-infective action. Xiong Huang supports Chan Su's ability to break down toxic accumulations in sores and abscesses.

When to use: Boils, carbuncles, scrofula, and other toxic sores where strong external or internal toxin-attacking action is needed. This pairing appears in both Liu Shen Wan and Chan Su Wan.

Key Formulas

These well-known formulas feature Chan Su in a prominent role

Liu Shen Wan 六神丸 Deputy

Liu Shen Wan (Six Spirits Pill) is the most famous formula containing Chan Su and its best clinical showcase. Chan Su serves as Deputy alongside Xiong Huang, clearing toxin and relieving pain. The formula treats severe sore throat, tonsillitis, boils, and skin infections. It perfectly demonstrates Chan Su's toxin-attacking and pain-relieving actions in a carefully balanced combination that moderates its toxicity through pairing with Niu Huang and Bing Pian.

Comparable Ingredients

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

Chan Tui
Chan Su vs Chan Tui

Despite the similar name, Chan Tui (cicada moulting) is an entirely different substance from a completely different animal. Chan Tui is cool in nature and disperses Wind-Heat from the exterior and throat, used for milder sore throats and skin rashes. Chan Su is warm, toxic, and far more powerful, attacking deep-seated Fire toxin in severe infections. Chan Tui is gentle and safe; Chan Su is potent and toxic. They are not interchangeable.

Niu Huang
Chan Su vs Niu Huang

Both clear Heat toxin and treat sore throat and sores, but Niu Huang is cool and works by clearing Heart Heat and calming the spirit, while Chan Su is warm and works by forcefully attacking toxin and opening orifices with its acrid, penetrating nature. Niu Huang is safer and can be used more broadly; Chan Su is more toxic and reserved for severe conditions. In practice, they are frequently combined rather than used as alternatives.

Identity & Adulterants

Related species and common adulterations to be aware of when sourcing Chan Su

Chan Su is sometimes adulterated with standard painkillers such as paracetamol (acetaminophen), promethazine, and diclofenac, particularly in products marketed outside China for pain relief or as aphrodisiacs. Products sold under names like "Love Stone" and "Rock Hard" in Western markets have been found to contain Chan Su mixed with these pharmaceutical adulterants. Authentic Chan Su can be distinguished by its characteristic horn-like (角质) cross-section, the milky white reaction when water is dropped on its surface, the sneezing response to its powder, and the distinctive initial sweetness followed by prolonged numbing sensation on the tongue. Pharmacopoeia testing for bufadienolide content (cinobufagin and resibufogenin totalling at least 6%) is the definitive quality standard. Secretions from non-standard toad species or from toads collected in non-optimal seasons may have significantly lower active compound content and different toxicity profiles.

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

Toxicity Classification

Classical Chinese pharmacopoeia toxicity rating for Chan Su

Toxic

Chan Su contains highly toxic bufadienolides (bufalin, cinobufagin, resibufogenin, cinobufotalin) that are structurally and pharmacologically similar to digoxin. These compounds inhibit Na+/K+-ATPase and produce powerful cardiac effects. Poisoning closely resembles digitalis toxicity: nausea, vomiting, abdominal pain, bradycardia, irregular heartbeat, AV conduction block, ventricular arrhythmias, and in severe cases cardiac arrest. CNS symptoms include shortness of breath, seizures, and coma. Deaths have been documented both in China and internationally. The LD50 in mice is approximately 41 mg/kg (IV) and 96.6 mg/kg (subcutaneous) for crude Chan Su. Individual components like bufalin are far more toxic. Boiling significantly reduces toxicity. Processing with alcohol (酒炙, wine-frying) and combining with other herbs in formulas like Liu Shen Wan helps control the dose and moderate toxicity. In cases of poisoning, treatment follows the same protocol as digoxin toxicity: digoxin-specific Fab antibody fragments (Digibind) have been shown effective in animal studies and human case reports. Atropine may partially counteract the bradycardia. Safety depends entirely on strict dose control: the internal dose must not exceed 0.015-0.03g per administration, always in pill or powder form combined with other medicinals, never as a decoction or taken alone.

Contraindications

Situations where Chan Su should not be used or requires extra caution

Avoid

Pregnancy. Chan Su contains bufadienolides that have been shown in animal studies to increase fetal resorption and decrease fetal weight. The substance is classified as strictly prohibited during pregnancy in TCM.

Avoid

Concurrent use of cardiac glycosides (digoxin, digitoxin). Chan Su contains bufadienolides structurally similar to digoxin, and combined use can produce additive cardiotoxic effects including fatal arrhythmias.

Avoid

Patients with serious cardiac arrhythmias, heart block, or bradycardia. The cardioactive steroids in Chan Su (bufalin, cinobufagin, resibufogenin) directly affect cardiac conduction and can worsen these conditions.

Avoid

Contact with eyes or open mucous membranes. External application of Chan Su near the eyes can cause severe swelling, redness, and in serious cases, temporary blindness. Classical texts note this can be treated with purple grass (zi cao) juice.

Avoid

Excessive oral dosage or prolonged internal use. The therapeutic window is extremely narrow (0.015-0.03g per dose). Even small overdoses can produce life-threatening cardiac toxicity resembling digoxin poisoning.

Caution

Patients with hypokalemia or electrolyte imbalances. Low potassium sensitizes the myocardium to the cardiac glycoside-like effects of bufadienolides, increasing risk of arrhythmias at lower doses.

Caution

Kidney or liver impairment. Impaired metabolism and excretion may lead to accumulation of toxic bufadienolides, requiring dose reduction or avoidance.

Caution

Elderly or frail patients. These populations are more susceptible to the cardiotoxic and CNS effects of Chan Su, requiring extra caution with dosing.

Caution

Use as a single-ingredient internal preparation. Classical sources emphasize that Chan Su should never be taken alone internally but must always be combined with other medicinals in pill or powder form to buffer its toxicity.

Special Populations

Important considerations for pregnancy, breastfeeding, and pediatric use

Pregnancy

Absolutely contraindicated during pregnancy. Animal studies have demonstrated that Chan Su at toxic doses increases fetal resorption and fetal death in pregnant mice, along with maternal liver and kidney damage. Its bufadienolide components have potent cardioactive effects that could affect fetal cardiac development. Classical sources explicitly list it as prohibited during pregnancy (孕妇忌用). The narrow therapeutic window and severe toxicity profile make any use during pregnancy unacceptably dangerous.

Breastfeeding

Contraindicated during breastfeeding. Chan Su's toxic bufadienolide components (bufalin, cinobufagin) are lipophilic steroid compounds that are likely to transfer into breast milk. Given their structural similarity to cardiac glycosides and extremely low toxic thresholds, even trace amounts could pose a serious risk to nursing infants, whose immature liver and kidney function cannot adequately metabolize these substances. No safety data exists for lactation use.

Children

Use with extreme caution in children. Chan Su has been used historically for childhood nutritional deficiency (疳积) and brain gan, but only in minute doses and always under expert supervision. Children are far more susceptible to the cardiotoxic effects of bufadienolides due to their lower body weight and immature organ function. Doses must be substantially reduced from the adult range. External application should also be used with great care, avoiding contact with eyes and mucous membranes. Given the extremely narrow therapeutic window and high toxicity risk, use in children should only be considered by experienced practitioners when safer alternatives are insufficient.

Drug Interactions

If you are taking pharmaceutical medications, be aware of these potential interactions with Chan Su

Cardiac glycosides (digoxin, digitoxin): This is the most critical interaction. Chan Su's bufadienolides (bufalin, cinobufagin, resibufogenin) are structurally analogous to digoxin and act by the same mechanism (Na+/K+-ATPase inhibition). Concurrent use produces additive or synergistic cardiotoxicity, potentially causing fatal arrhythmias. Chan Su also cross-reacts with digoxin immunoassays, producing falsely elevated digoxin blood level readings.

Antiarrhythmic drugs (amiodarone, quinidine, beta-blockers, calcium channel blockers): These drugs affect cardiac conduction through overlapping pathways. Combined use with Chan Su's cardioactive steroids may potentiate bradycardia, heart block, or other conduction disturbances.

Potassium-depleting diuretics (furosemide, hydrochlorothiazide): Hypokalemia sensitizes the myocardium to the toxic effects of cardiac glycoside-like compounds. Patients on such diuretics face increased risk of Chan Su-related cardiac toxicity even at standard doses.

Corticosteroids: Long-term corticosteroid use can cause electrolyte disturbances (particularly potassium depletion) that increase susceptibility to cardiac glycoside toxicity.

Dietary Advice

Foods and dietary considerations when taking Chan Su

Avoid alcohol while taking Chan Su preparations, as alcohol can increase absorption of the lipophilic bufadienolides and potentially enhance both therapeutic and toxic cardiac effects. Maintain adequate potassium intake through foods such as bananas, sweet potatoes, and leafy greens, since low potassium levels increase vulnerability to the cardiac glycoside-like toxicity of Chan Su. Avoid grapefruit and grapefruit juice, which may interfere with the metabolism of steroid-type compounds.

Botanical Description

Physical characteristics and morphology of the Chan Su source animal

Chan Su is not derived from a plant but from an animal source. It is the dried secretion collected from the parotid glands (耳后腺) and skin glands of two species of toad: the Chinese Giant Toad (Bufo bufo gargarizans Cantor) and the Black-Spectacled Toad (Bufo melanostictus Schneider), both belonging to the family Bufonidae.

The Chinese Giant Toad is a large, stocky amphibian with rough, warty skin covered in numerous glandular bumps. It is typically brown, grey, or olive in colour. The prominent parotid glands behind each eye are the primary source of the medicinal secretion. These toads are nocturnal, feeding on insects, and are commonly found near water sources in fields, gardens, and damp lowland areas across eastern China. During collection, the live toad is washed and its parotid glands are squeezed to express a thick, white, milky venom. This venom is collected onto glass plates, oil paper, or mulberry leaves, dried in the shade, and processed into the final medicinal product. Iron implements must be avoided during collection, as they cause the secretion to turn black and degrade in quality.

Sourcing & Harvesting

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

Harvesting season

Summer and autumn (June through October), when toads are most active and glandular secretions are richest.

Primary growing regions

Chan Su is primarily produced in Jilin, Shandong, Liaoning, and Jiangsu provinces of China. Shandong province, particularly the areas around Heze and Jining, is traditionally considered one of the most important producing regions. The toads are also collected from Hebei, Anhui, Sichuan, and Zhejiang. Quality varies with species, season of collection, and local environmental conditions rather than strictly following the dao di (terroir) concept as with plant medicines.

Quality indicators

Good quality Chan Su in its round cake form (团蟾酥) should be approximately 10 cm in diameter and 2 cm thick, weighing around 100g. The surface should be smooth and yellow-brown to reddish-brown in colour. The texture should be hard and difficult to break. The cross-section should be horn-like (角质), glossy, and reddish-brown. Flake form (片蟾酥) should be brittle, translucent, and reddish-brown. A key authenticity test: when a drop of water is placed on the surface, it should turn milky white and form a slight raised bubble. A broken piece will re-adhere when moistened. The powder causes sneezing when inhaled. The taste is initially sweet, followed by a persistent numbing, peppery sensation on the tongue. The Chinese Pharmacopoeia requires a combined content of cinobufagin (华蟾酥毒基) and resibufogenin (脂蟾毒配基) of at least 6%. Moisture content should not exceed 13%.

Classical Texts

Key passages from the classical Chinese medical texts that describe Chan Su and its therapeutic uses

《药性论》(Yao Xing Lun)

Original: 脑疳，以奶汁调滴鼻中。

Translation: For childhood brain gan (nutritional deficiency with neurological symptoms), mix with breast milk and instill drops into the nose.

Note: This is the earliest recorded mention of Chan Su as a medicinal substance, where it was called "toad brow grease" (蟾蜍眉脂).

《本草纲目》(Ben Cao Gang Mu) — Li Shizhen

Original: 甘辛，温，有毒。治发背疔疮，一切恶肿。

Translation: Sweet and acrid in flavour, warm in nature, and toxic. Treats back abscesses, boils, and all manner of malignant swellings.

《本草汇言》(Ben Cao Hui Yan)

Original: 蟾酥，疗疳积，消臌胀，解疔毒之药也。能化解一切瘀郁壅滞诸疾，如积毒、积块、积胀、内疔痈肿之证，有攻毒拔毒之功也。

Translation: Chan Su treats childhood nutritional deficiency, relieves abdominal distension, and resolves toxic boils. It can break through all stagnation and obstruction, including toxic accumulations, masses, distension, and internal abscesses. It has the power to attack and draw out toxins.

《本草求真》(Ben Cao Qiu Zhen)

Original: 蟾酥，味辛气温有毒，能拔一切风火热毒之邪，使之外出。盖邪气着人肌肉，郁而不解，则或见为疔肿发背……故必用此辛温以治，盖辛主散，温主行，使邪尽从汗出，不留内入，而热自可以除矣。性有毒，止可外治取效；即或用丸剂，亦止二、三、四厘而已，多则能使毒人。

Translation: Chan Su is acrid in taste, warm in Qi, and toxic. It can draw out all types of wind, fire, and heat-toxin pathogenic influences, driving them outward. When pathogenic Qi lodges in the flesh and becomes stuck, it manifests as boils, back abscesses, and similar conditions. The acrid nature disperses while the warm nature mobilizes, expelling the pathogen through the skin and preventing it from penetrating inward, thereby eliminating the heat. Because it is toxic, it is best used externally. If taken internally in pill form, the dose should only be 2-4 li (roughly 0.01-0.02g). Higher doses can poison a person.

《本草便读》(Ben Cao Bian Du)

Original: 蟾酥，善开窍辟恶搜邪，惟诸闭证救急方中用之，以开其闭。然服食总宜谨慎，试以少许置肌肤，顿时起泡蚀烂；其性可知。

Translation: Chan Su excels at opening the orifices, repelling foulness, and searching out pathogens. It is used specifically in emergency formulas for closure patterns, to force them open. However, it must always be used with extreme caution. If even a small amount is placed on the skin, it immediately raises blisters and causes corrosion, which gives a clear indication of its potency.

Historical Context

The history and evolution of Chan Su's use in Chinese medicine over the centuries

Chan Su first appeared in the medical literature under the name "toad brow grease" (蟾蜍眉脂) in the Tang dynasty text Yao Xing Lun (《药性论》). The name "Chan Su" (蟾酥) itself was coined later in the Song dynasty text Ben Cao Yan Yi (《本草衍义》), which described the collection method: squeezing the white secretion from between the toad's brows onto oiled paper. Li Shizhen's Ming dynasty Ben Cao Gang Mu expanded on the collection technique and solidified its use for treating abscesses, boils, and toxic swellings.

Throughout Chinese medical history, Chan Su has been valued as a potent "attacking toxin" (攻毒) substance, embodying the principle of "using poison to attack poison" (以毒攻毒). It became a key ingredient in several famous formulas, most notably Liu Shen Wan (六神丸, "Six Spirits Pill"), a widely used remedy for sore throat and toxic swellings, as well as She Xiang Bao Xin Wan (麝香保心丸) for heart conditions. In Japan, a related formula called Kyushin (救心) uses Chan Su as its core cardiotonic ingredient. The character "蟾" (chan) means toad, while "酥" (su) originally meant a paste or cream-like substance, referring to the waxy secretion collected from the glands. Modern pharmacological research since the mid-20th century has revealed that its dramatic cardiac effects are due to bufadienolides that act similarly to digitalis glycosides, validating centuries of empirical use while also explaining its notorious toxicity.

Modern Research

4 published studies investigating the pharmacological effects or clinical outcomes of Chan Su

1

Venenum bufonis: An overview of its traditional use, natural product chemistry, pharmacology, pharmacokinetics and toxicology (Review, 2019)

Wei WL, Hou JJ, Wang X, et al. Journal of Ethnopharmacology, 2019, 237: 215-235.

A comprehensive review covering Chan Su's chemical composition (bufadienolides, indole alkaloids, sterols), pharmacological activities (cardiotonic, anti-tumor, anti-inflammatory, local anesthetic, CNS stimulant), pharmacokinetics, and toxicological profile. The review highlighted that bufadienolides inhibit Na+/K+-ATPase and that the therapeutic window is very narrow.

Link
2

Bufalin and cinobufagin induce apoptosis of human hepatocellular carcinoma cells via Fas- and mitochondria-mediated pathways (In vitro study, 2011)

Qi F, Li A, Zhao L, et al. Cancer Science, 2011, 102(5): 951-958.

This study demonstrated that bufalin and cinobufagin, two major components of Chan Su, induced apoptosis in HepG2 liver cancer cells through both Fas (death receptor) and mitochondrial pathways, involving caspase activation and Bcl-2 family protein regulation. A caspase-10-dependent pathway appeared to play a particularly important role.

PubMed
3

The Effectiveness and Safety of Cinobufotalin Injection as an Adjunctive Treatment for Lung Cancer: A Meta-Analysis of Randomized Controlled Trials (Meta-analysis, 2021)

Li LL, Su YX, Mao Y, et al. Evidence-Based Complementary and Alternative Medicine, 2021, 2021: 8852261.

This meta-analysis of 21 RCTs (1,735 patients) evaluated cinobufotalin injection (a Chan Su-derived preparation) combined with chemotherapy for lung cancer. The combination improved objective response rates and quality of life compared to chemotherapy alone, with reduced incidence of certain adverse effects like leukopenia.

Link
4

Examination for toxicity of a Chinese drug, the toad glandular secretory product Chan Su, in pregnant mice and embryos (Animal study, 1995)

Lau JH, et al. (1995). PubMed indexed.

Chan Su was administered to pregnant mice during embryonic organogenesis. Doses below 50 mg/kg did not produce detectable changes, but at 50 mg/kg it caused liver and kidney damage in the mothers and increased fetal resorption and death. No structural malformations were observed in surviving fetuses, but fetal weight was reduced.

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.