Herb Tuber (块茎 kuài jīng / 块根 kuài gēn)

Gan Sui

Kansui root · 甘遂

Euphorbia kansui T.N. Liou ex T.P. Wang · Radix Euphorbiae Kansui

Also known as: Kan Sui, Kansui Euphorbia root, Gān Zé (甘泽),

Gan Sui (Kansui root) plant

Images shown are for educational purposes only

Gan Sui is one of the most powerful water-expelling herbs in the Chinese materia medica, used for severe fluid accumulation in the chest or abdomen such as ascites and pleural effusion. Because it is toxic and very strong in action, it is only used for acute excess conditions under professional supervision, never for weak or deficient patients. It is typically processed with vinegar to reduce toxicity before internal use.

Category Harsh expellants (峻下逐水药)
Therapeutic focus Fluid Retention and Edema Fluid Accumulation in Chest and Abdomen Intestinal Obstruction

TCM Properties

Temperature

Cold

Taste

Bitter (苦 kǔ), Sweet (甘 gān)

Channels entered

Lungs, Kidneys, Large Intestine

Parts used

Tuber (块茎 kuài jīng / 块根 kuài gēn)

Educational content • Consult qualified TCM practitioners for diagnosis and treatment

What This Herb Does

Every herb has a specific set of actions — here's what Gan Sui does in the body, explained in both everyday and TCM terms

Therapeutic focus

In practical terms, Gan Sui is primarily used to support these areas of health:

Fluid Retention and Edema Fluid Accumulation in Chest and Abdomen Intestinal Obstruction

TCM Actions

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

Drains Water and Expels Phlegm-Fluids Disperses Swelling and Dissipates Nodules Breaks Up Accumulations Promotes Bowel and Urinary Movement

How these actions work

'Drains water and expels congested fluids' is the primary and most important action of Gan Sui. This means it powerfully forces accumulated pathological fluid out of the body through the stool and urine. In TCM, when water or thin mucus (called 'Phlegm-Fluids' or 'retained Fluid') collects in areas like the chest cavity, abdominal cavity, or under the skin and the body cannot resolve it through gentler means, a drastic approach is needed. Gan Sui is considered the strongest of the three classical water-expelling herbs (alongside Da Ji and Yuan Hua). Specifically, Gan Sui is said to excel at draining water from the channels and collaterals (经隧 jīng suì), meaning it can reach fluid trapped in the body's deeper passageways that other herbs cannot access.

'Reduces swelling and dissipates nodules' refers to its external use. When ground into powder and mixed with water, Gan Sui paste can be applied topically to swellings and abscesses caused by Damp-Heat accumulation, particularly in the early stages. It helps break down the stagnation and reduce inflammation locally.

'Breaks up accumulations' relates to its ability to address masses and accumulations in the abdomen. In classical texts, the Shen Nong Ben Cao Jing notes that it treats abdominal masses (zheng jia) and hard accumulations. This action is connected to its forceful downward-purging nature, which can dislodge and expel pathological substances that have congealed in the abdomen.

'Opens the bowels and promotes urination' describes its dual action on both urination and bowel movements. Because it is bitter and cold, it descends strongly, stimulating both the intestines and the urinary tract to move fluid downward and out of the body. This makes it useful when both stool and urine are blocked due to severe fluid congestion.

Patterns Addressed

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

Why Gan Sui addresses this pattern

Gan Sui is the foremost herb for patterns where pathological water has accumulated massively in the body's cavities. Its bitter, cold nature and affinity for the Lung, Kidney, and Large Intestine channels allow it to powerfully drive water downward and out through the bowels and urinary tract. Classical sources describe it as uniquely able to 'travel the channels and collaterals' (行经隧), meaning it can reach and expel fluid lodged in deep, hidden spaces that gentler diuretics cannot access. It is only used when the water accumulation is an excess condition in a patient with sufficient constitution to withstand its drastic action.

A practitioner would look for one or more of these signs

Ascites

Abdominal distension with fluid accumulation

Edema

Generalized swelling, especially below the waist

Oliguria

Scanty or blocked urination

Abdominal Distention

Drum-like abdominal fullness

Commonly Used For

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

Arises from: Water Accumulation

TCM Interpretation

TCM understands ascites primarily as a condition where the body's water metabolism has broken down. The Spleen fails to transform and transport fluids, the Kidneys fail to regulate water, and the Lungs fail to distribute and descend fluid. When all three organs falter, water collects in the lower abdomen, producing the 'drum-like distension' (鼓胀 gǔ zhàng) that corresponds to what modern medicine calls ascites. In acute and severe cases, the accumulated water itself becomes a pathogenic factor that further obstructs Qi movement and organ function, creating a vicious cycle. TCM classifies this as an excess pattern requiring drastic intervention.

Why Gan Sui Helps

Gan Sui directly addresses the core pathology by forcefully expelling the accumulated water through the bowels. Its bitter, cold nature descends powerfully, and its affinity for the Lung, Kidney, and Large Intestine channels means it can act on the entire water metabolism pathway simultaneously. Classical texts describe it as the strongest of all water-expelling herbs, able to 'travel the channels and collaterals' to reach fluid in hidden recesses. In Shi Zao Tang, the classic formula for this condition, Gan Sui serves as the King herb precisely because of this unmatched water-draining power. However, because it is so drastic, it is only used when the patient still has sufficient constitutional strength, and treatment is stopped as soon as the fluid is expelled.

Also commonly used for

Edema

Severe generalized edema with excess pattern

Intestinal Obstruction

Acute obstruction with fluid accumulation

Constipation

Severe constipation with abdominal fluid retention

Epilepsy

Phlegm-type epilepsy with convulsions

Acute Meningitis

Heat and water binding in the abdomen

Acute Pancreatitis

Used in combination formulas for severe cases

Herb Properties

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

Temperature

Cold

Taste

Bitter (苦 kǔ), Sweet (甘 gān)

Channels Entered

Lungs Kidneys Large Intestine

Parts Used

Tuber (块茎 kuài jīng / 块根 kuài gēn)

Dosage & Preparation

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

Standard dosage

0.5-1g (in pill or powder form per dose)

Maximum dosage

Do not exceed 1g per dose in pill/powder form. This herb is toxic and should only be used in short courses under strict practitioner supervision.

Dosage notes

Gan Sui's active and toxic components are soluble in alcohol but not in water. Therefore, plain water decoctions have little purgative effect and the herb is typically administered as powder in pills or capsules, not as a standard decoction. The standard internal dose is 0.5 to 1g per administration in processed (vinegar-fried) form. Only processed Gan Sui should be taken internally; the raw form is reserved for external application only. To reduce gastrointestinal side effects such as nausea and abdominal pain, the powder can be taken in capsules or with a warm jujube (Da Zao) decoction. The herb should be used only for robust patients with excess-type patterns and stopped as soon as the therapeutic goal (e.g. drainage of fluid accumulation) is achieved.

Preparation

Gan Sui's active purgative compounds are alcohol-soluble, not water-soluble. Standard water decoction is ineffective and not recommended. The herb should be taken as powder in pills or capsules. Only the processed form (醋甘遂, vinegar-fried Gan Sui) should be used internally. Raw Gan Sui (生甘遂) is for external use only. Taking the powder with warm jujube (Da Zao) decoction or encapsulating it can reduce gastrointestinal irritation.

Processing Methods

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

Processing method

The cleaned Gan Sui root is stir-fried with rice vinegar until slightly dry, then cooled. The standard ratio is 30 kg vinegar per 100 kg of herb.

How it changes properties

Vinegar processing significantly reduces the herb's toxicity by decreasing the content of toxic terpenoid compounds (such as ingenol-type diterpenes and kansuinines). The cathartic (purging) action becomes milder and more controllable. The thermal nature remains cold, but the harshness is tempered. Research shows the contents of most toxic terpenoids decrease by 7% to 95% after vinegar processing.

When to use this form

This is the standard form for all internal use. Raw Gan Sui is too toxic for oral administration and is reserved for external application only. Whenever Gan Sui is taken internally, whether in pills, powders, or decoctions, the vinegar-processed form should be used.

Common Herb Pairs

These ingredients are traditionally combined with Gan Sui for enhanced therapeutic effect

Da Ji
Da Ji 1:1 (equal parts)

Gan Sui drains water from the channels and collaterals (经隧) while Da Ji drains water from the organs and viscera (脏腑). Together they create a comprehensive water-expelling action that reaches both superficial pathways and deep organ reservoirs, making the pair far more effective than either herb alone.

When to use: Severe fluid accumulation involving both the channels and organs, such as ascites, generalized edema, or pleural effusion where fluid is extensive. Always in robust patients with excess conditions.

Yuan Hua
Yuan Hua 1:1 (equal parts, as in Shi Zao Tang)

Gan Sui forcefully drives water through the channels and collaterals, while Yuan Hua specifically targets hidden fluid and phlegm lodged in the chest and flanks. The combination ensures that both deep-seated and superficial fluid is expelled, particularly from the thoracic cavity.

When to use: Suspended Fluid (悬饮) pattern with cough, chest and flank pain, and shortness of breath from fluid in the pleural space. This is the core pairing in Shi Zao Tang.

Bai Jie Zi
Bai Jie Zi 1:1 (equal parts, as in Kong Xian Dan)

Gan Sui breaks up accumulations and expels water from the channels, while Bai Jie Zi (white mustard seed) disperses phlegm lodged in the space between the skin and membranes (皮里膜外). Together they address both water and phlegm retention across all body layers, from deep channels to the tissue spaces.

When to use: Phlegm-Fluid lodged in the chest, flanks, and body tissues causing shifting pain, fullness, or numbness. This is the core pairing in Kong Xian Dan (Control Phlegm Pill).

Da Huang
Da Huang Gan Sui 1g : Da Huang 10g (Gan Sui used in small amounts as powder)

Gan Sui powerfully expels water and breaks through fluid accumulation, while Da Huang (rhubarb) purges Heat and drives stool downward. Together they simultaneously clear Heat and drain water, making them effective against combined water-Heat binding in the chest and abdomen.

When to use: Water-Heat Chest Bind (水热结胸) pattern with hard, painful fullness in the epigastrium, constipation, thirst, and a tense pulse. This is the core combination in Da Xian Xiong Tang.

Key Formulas

These well-known formulas feature Gan Sui in a prominent role

Shi Zao Tang 十棗湯 King

The definitive water-expelling formula from the Shang Han Lun and Jin Gui Yao Lue. Gan Sui serves as King because it is the most powerful of the three cathartic herbs (alongside Da Ji and Yuan Hua), excelling at draining water from the channels and collaterals. This formula is the primary clinical showcase of Gan Sui's core action of expelling severe fluid accumulation from the chest and abdomen.

Gan Sui Ban Xia Tang 甘遂半夏湯 King

From the Jin Gui Yao Lue by Zhang Zhongjing, this formula treats Retained Fluid (留饮) lodged below the ribs causing persistent fullness. Notably, it combines Gan Sui with Gan Cao (licorice), which is classically listed as an incompatible pair (十八反). Zhang Zhongjing's deliberate use of this combination demonstrates that the incompatibility rule has exceptions in skilled hands, making this formula a historically significant case study.

Kong Xian Dan 控涎丹 Deputy

From the San Yin Ji Yi Bing Zheng Fang Lun (Song dynasty), this pill formula is a milder derivative of Shi Zao Tang. It replaces Yuan Hua with Bai Jie Zi and is taken as small pills over time rather than a single drastic dose. Gan Sui contributes its channel-penetrating water-draining action, working with Da Ji and Bai Jie Zi to address chronic Phlegm-Fluid lodged throughout the body.

Comparable Ingredients

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

Da Ji
Gan Sui vs Da Ji

Both are powerful water-expelling herbs often used together. The key difference is their target: Gan Sui drains water from the channels and collaterals (经隧之水), while Da Ji drains water from the organs and viscera (脏腑之水). Gan Sui is considered the stronger of the two in overall cathartic potency. Da Ji also has some Blood-moving and detoxifying actions that Gan Sui lacks.

Yuan Hua
Gan Sui vs Yuan Hua

Both expel water, but Yuan Hua specifically targets chest and flank fluid and phlegm, and also has cough-suppressing and phlegm-resolving properties. Yuan Hua is warm in temperature (unlike the cold Gan Sui), making it more suitable when cold-type fluid stagnation predominates. Gan Sui is the strongest cathartic of the three, while Yuan Hua is the mildest.

Qian Niu Zi
Gan Sui vs Qian Niu Zi

Both have strong water-expelling and cathartic actions. Qian Niu Zi (morning glory seed) acts more quickly but its effect is less sustained, while Gan Sui acts more gradually but reaches deeper fluid accumulations in the channels. A classical teaching from Ben Cao Xin Bian notes that Gan Sui's water-expelling action is slower but deeper, while Qian Niu Zi is faster but more superficial. They are sometimes combined for a balanced effect.

Common Substitutes & Adulterants

Related species and common adulterations to be aware of when sourcing Gan Sui

Gan Sui can be confused with or adulterated by the roots of other Euphorbia species, particularly Euphorbia pekinensis (Da Ji / 京大戟), which belongs to the same family but has different actions and indications. The two can be distinguished by root morphology: authentic Gan Sui has a characteristic bead-like (moniliform) shape with constrictions along the root, while Da Ji roots are more uniformly conical. Additionally, Gan Sui's cross-section is predominantly starchy and white, whereas Da Ji shows a more fibrous structure. The roots of Stellera chamaejasme (Lang Du / 狼毒) have also occasionally been confused with Gan Sui in some regions. Reliable identification requires checking for the bead-shaped swellings, white powdery cross-section, and the faintly sweet-then-acrid taste profile.

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

Toxicity Classification

Classical Chinese pharmacopoeia toxicity rating for Gan Sui

Toxic

Gan Sui's toxic components are primarily diterpene esters, including ingenane-type diterpenes, kansuinine A and B (甘遂萜酯A、B), kansuiphorins, and related compounds derived from the ingenol and jatrophane structural families. These substances have strong irritant effects on mucous membranes and skin, and at higher doses can damage the heart, liver, and kidneys. Some of these diterpenes also possess tumor-promoting (Epstein-Barr virus early antigen-activating) properties alongside their anti-tumor effects, illustrating the classical principle that the toxic and therapeutic components are closely intertwined. Symptoms of Gan Sui toxicity include severe nausea, vomiting, intense abdominal pain, profuse watery diarrhea, respiratory depression, and a drop in blood pressure. In animal studies, continuous high-dose administration caused histological changes in cardiac muscle, liver tissue, and kidneys. Proper processing (炮制) is essential to make Gan Sui safe for internal use. The raw herb (生甘遂) is approximately six times more irritating than processed forms. Vinegar processing (醋炙甘遂) is the most common method, which significantly reduces both irritation and toxicity while preserving therapeutic activity. Other traditional methods include cooking with tofu (豆腐制) or roasting with wheat bran (麦麸煨). The raw form should only be used externally. Additionally, the active purgative compounds are alcohol-soluble but not water-soluble, so plain water decoctions have minimal purgative or toxic effect. For this reason, Gan Sui is typically administered as powder in pills or capsules rather than as a decoction. Taking the dose with jujube (Da Zao) soup or encapsulating the powder can also reduce gastrointestinal side effects.

Contraindications

Situations where Gan Sui should not be used or requires extra caution

Avoid

Pregnancy. Gan Sui has demonstrated abortifacient and labor-inducing effects in animal studies. It is strongly contraindicated during pregnancy due to its drastic purgative action and potential to cause uterine contractions.

Avoid

Concurrent use with Gan Cao (Glycyrrhiza / licorice) or any formula containing Gan Cao. Gan Sui is listed among the classical Eighteen Incompatibilities (十八反) as being incompatible with Gan Cao. Modern research has shown that combining the two inhibits the metabolism of Gan Sui's toxic diterpene components (kansuinine A and B), causing accumulation and increased toxicity.

Avoid

Deficiency-Cold type edema (虚寒阴水). Gan Sui is bitter, cold, and drastically draining. Using it in patients whose water retention stems from Spleen-Kidney Yang deficiency will further damage the body's Yang Qi and worsen the condition.

Avoid

Patients with general constitutional weakness or debility. As a potent purgative, Gan Sui can severely deplete Qi and fluids in those who lack the physical reserves to tolerate its harsh action.

Avoid

Prolonged or repeated use. Gan Sui must not be used continuously or for extended periods. It is intended for short-term, acute intervention only.

Caution

Patients with pre-existing gastrointestinal inflammation or ulceration. Gan Sui's diterpene esters are strongly irritating to the mucous membranes of the digestive tract, which could worsen existing lesions.

Caution

Patients with compromised liver or kidney function. Animal studies have shown that Gan Sui extracts can cause histological changes in the heart, liver, and kidneys at higher doses.

Classical Incompatibilities

Traditional Chinese pharmacological incompatibilities — herbs or substances to avoid combining with Gan Sui

Gan Sui is one of the four herbs listed in the Eighteen Incompatibilities (十八反) as being incompatible with Gan Cao (Glycyrrhiza / licorice). The classical mnemonic states: "藻戟遂芫俱战草" (Hai Zao, Da Ji, Gan Sui, and Yuan Hua all oppose Gan Cao). This incompatibility is recorded from the earliest sources including Tao Hongjing's Ben Cao Jing Ji Zhu, and codified in the Eighteen Incompatibilities verse first widely circulated from the Jin-Yuan period. Modern pharmacological research has confirmed a mechanistic basis: Gan Cao's glycyrrhizic acid inhibits the CYP450 enzymes responsible for metabolizing Gan Sui's toxic diterpenes, leading to toxic accumulation. Note: Zhang Zhongjing's Gan Sui Ban Xia Tang from the Jin Gui Yao Lue deliberately combines the two herbs, but this is considered an advanced application by a master physician and should not be taken as license for casual use.

Special Populations

Important considerations for pregnancy, breastfeeding, and pediatric use

Pregnancy

Absolutely contraindicated in pregnancy. Animal studies have demonstrated that Gan Sui ethanol extract has clear abortifacient and labor-inducing effects in pregnant guinea pigs, with onset at doses as low as 10 mg/kg. The mechanism involves direct uterine stimulation combined with the severe purging and fluid loss caused by the herb, which can threaten both the mother and fetus. No dose is considered safe during pregnancy.

Breastfeeding

Contraindicated during breastfeeding. Gan Sui's toxic diterpene esters are lipophilic compounds that may transfer into breast milk. The herb's strong purgative action can also cause severe fluid and electrolyte loss in the mother, potentially affecting milk production. There is no safety data supporting its use during lactation. If a nursing mother must use this herb in an emergency clinical situation, breastfeeding should be temporarily suspended.

Children

Gan Sui is generally not appropriate for children. Its drastic purgative action and toxicity make it extremely risky for pediatric use. Children are more vulnerable to fluid and electrolyte depletion, and their smaller body mass means toxic effects can occur at much lower absolute doses. If absolutely necessary in a life-threatening situation (such as severe fluid accumulation unresponsive to other treatment), only a fraction of the adult dose should be used under very close supervision by an experienced practitioner. There is no established safe pediatric dosage.

Drug Interactions

If you are taking pharmaceutical medications, be aware of these potential interactions with Gan Sui

Diuretics: Gan Sui has potent water-expelling effects. Concurrent use with pharmaceutical diuretics (furosemide, hydrochlorothiazide, spironolactone) could lead to dangerous fluid and electrolyte depletion, particularly hypokalemia, dehydration, and hypotension.

Cardiac glycosides (digoxin): The severe fluid and potassium loss caused by Gan Sui's drastic purging could potentiate digoxin toxicity by lowering serum potassium levels.

Antihypertensive medications: Gan Sui can cause drops in blood pressure at higher doses. Combined use with antihypertensives could result in severe hypotension.

CYP450 substrates: Research has shown that Gan Sui's toxic diterpenes are metabolized by multiple CYP450 isoenzymes (CYP3A4, CYP2D6, CYP2C9, CYP1A2, CYP2C19). Drugs that inhibit these enzymes could slow the clearance of Gan Sui's toxic compounds and increase toxicity risk.

Corticosteroids: Both Gan Sui and corticosteroids can affect fluid and electrolyte balance. Concurrent use may compound the risk of metabolic disturbance.

Dietary Advice

Foods and dietary considerations when taking Gan Sui

When taking Gan Sui, avoid cold, raw, and hard-to-digest foods, as these place additional burden on an already stressed digestive system. After the purgative effect has taken hold, follow with easily digestible congee (rice porridge) to gently restore the Stomach and Spleen. Avoid alcohol, which could increase the solubility and absorption of toxic diterpene components. Avoid any foods or supplements containing licorice (Gan Cao), including licorice-flavored teas, candies, or herbal blends, due to the classical incompatibility.

Botanical Description

Physical characteristics and morphology of the Gan Sui source plant

Euphorbia kansui T.N. Liou ex S.B. Ho is a perennial herbaceous plant of the Euphorbiaceae (spurge) family, endemic to China. The plant has erect stems that become somewhat woody at the base, with alternate, narrow lance-shaped to linear leaves that are arranged in whorls of 5 to 9 at the top of the stem, from which radiate an equal number of branching flower stalks. The roots are long and cylindrical, extending up to 40 cm, with distinctive bead-like (moniliform) swellings along their length, covered in a brown outer bark with white flesh inside. The stems and leaves, when cut, exude a milky white latex characteristic of the Euphorbia genus. Small yellowish-green flowers appear in the typical cup-shaped cyathia of the genus during summer (April to June), followed by three-angled capsule fruits that ripen from June to August.

The plant grows wild in low mountain slopes, wastelands, sandy ground, field margins, and roadsides across arid and semi-arid regions of northwestern and north-central China. It is now also cultivated commercially for medicinal use. The medicinal part is the dried tuberous root, collected in spring before flowering or in autumn after the aerial parts die back.

Sourcing & Harvesting

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

Harvesting season

Spring (before flowering) or late autumn (after aerial parts have withered and died back).

Primary growing regions

Primarily produced in Shaanxi, Gansu, Henan, Shanxi, and Shandong provinces of China. Historically, the best quality was said to come from the Zhongshan mountain valleys, with sources from Taishan and Jiangdong also considered excellent. Shaanxi and Gansu are regarded as the principal production areas, reflecting the herb's preference for arid, sandy, low-mountain terrain in north-central and northwestern China.

Quality indicators

Good quality Gan Sui root pieces are elliptical, elongated-cylindrical, or distinctively bead-shaped (连珠形), 1 to 5 cm long and 0.5 to 2.5 cm in diameter. The surface should be off-white to yellowish-white after the outer bark has been removed, with remnants of brown outer skin visible only in the concavities between segments. The texture should be brittle and easy to snap, revealing a starchy (powdery), white cross-section with faint radial lines in the wood. Heavier, more solid pieces are considered superior (重实者良). The taste should be slightly sweet initially, followed by a pungent, acrid bite. Avoid pieces that are hollow, lightweight, darkened, or overly fibrous, as these indicate poor quality or age.

Classical Texts

Key passages from the classical Chinese medical texts that describe Gan Sui and its therapeutic uses

Shen Nong Ben Cao Jing (《神农本草经》)

Original: 「主大腹疝瘕，腹满，面目浮肿，留饮宿食，破症坚积聚，利水谷道。」

Translation: "It principally treats abdominal distension with hernial masses, fullness of the abdomen, swelling of the face and eyes, retained fluid and stagnant food. It breaks up firm lumps and accumulations, and frees the waterways and digestive passages."

Ming Yi Bie Lu (《名医别录》)

Original: 「下五水，散膀胱留热，皮中痞，热气肿满。」

Translation: "It drains the five types of water, disperses retained heat in the Bladder, resolves subcutaneous glomus, and treats hot-type swelling and fullness."

Yao Xing Lun (《药性论》)

Original: 「能泻十二种水疾，治心腹坚满，下水，去痰水，主皮肤浮肿。」

Translation: "It can purge twelve types of water disease, treat hardness and fullness of the chest and abdomen, drive out water, eliminate phlegm-fluid, and address skin edema."

Ben Cao Gang Mu (《本草纲目》, Li Shizhen)

Original: 「泻肾经及隧道水湿，脚气，阴囊肿坠，痰迷癫痫，噎膈痞塞。」

Translation: "It drains dampness from the Kidney channel and the body's internal passages, and treats leg Qi, scrotal swelling and heaviness, epilepsy from phlegm obstruction, and blockage of the throat and diaphragm."

Zhen Zhu Nang (《珍珠囊》)

Original: 「水结胸中，非此不能除。」

Translation: "When water binds in the chest, nothing but this herb can remove it."

Tang Ye Ben Cao (《汤液本草》)

Original: 「甘遂可以通水，而其气直透达所结处。」

Translation: "Gan Sui can open the waterways, and its force penetrates directly to the site of obstruction."

Historical Context

The history and evolution of Gan Sui's use in Chinese medicine over the centuries

Gan Sui is one of the oldest recorded drastic purgatives in Chinese medicine, first documented in the Shen Nong Ben Cao Jing (compiled circa 1st-2nd century CE), where it was classified as a "lower-grade" (下品) herb, a category reserved for potent, often toxic substances intended for short-term treatment of disease rather than long-term health cultivation. Its ancient aliases include Zhu Tian (主田), Chong Ze (重泽), Ku Ze (苦泽), and Gui Chou (鬼丑), as recorded in the Wu Pu Ben Cao.

The herb's name "Gan Sui" (甘遂) literally means "sweet accomplishment" or "sweet passage," which is somewhat ironic given its bitter, acrid taste. Some scholars believe the "sweet" (甘) in the name refers to its slightly sweet initial taste before the biting pungency takes hold, while "sui" (遂) means "to flow through" or "accomplish," alluding to its powerful ability to force water to flow out of the body. It was famously called "the sage herb for draining water" (下水之圣药) by later commentators.

Perhaps the most historically significant use of Gan Sui appears in Zhang Zhongjing's Jin Gui Yao Lue (circa 200 CE), in the formula Gan Sui Ban Xia Tang, where Gan Sui is deliberately combined with Gan Cao, despite the two being listed as classically incompatible. This bold prescription for treating retained fluid has sparked centuries of debate about whether the Eighteen Incompatibilities should be regarded as absolute rules or contextual guidelines. Zhang Zhongjing also included Gan Sui in his famous Shi Zao Tang (Ten Jujubes Decoction) from the Shang Han Lun, paired with Da Ji and Yuan Hua, using jujube decoction as the vehicle to buffer the harshness of these three drastic purgatives.

Modern Research

5 published studies investigating the pharmacological effects or clinical outcomes of Gan Sui

1

Review: The Chemical and Biological Properties of Euphorbia kansui (2016)

Shen J, Kai J, Tang Y, Zhang L, Su S, Duan JA. Am J Chin Med. 2016;44(2):253-73.

A comprehensive review summarizing the chemical constituents (diterpenes, triterpenes, steroids) and biological activities (anti-tumor, anti-inflammatory, anti-viral, purgative) of Euphorbia kansui. The review highlighted that ingenane- and jatrophane-type diterpenes are the primary bioactive and toxic constituents, and discussed the dual nature of these compounds as both therapeutically active and toxic.

PubMed
2

Antitumor Agents, 119: Kansuiphorins A and B, Two Novel Antileukemic Diterpene Esters from Euphorbia kansui (Preclinical, 1991)

Wu TS, Lin YM, Haruna M, Pan DJ, Shingu T, Chen YP, et al. J Nat Prod. 1991;54(3):823-829.

The root extract of Euphorbia kansui demonstrated antileukemic activity against P-388 lymphocytic leukemia in mice. Bioassay-guided fractionation led to the isolation of two novel ingenol-type diterpene esters, kansuiphorin A and kansuiphorin B, which showed potent antileukemic activity at very low doses (0.1 and 0.5 mg/kg respectively). Kansuiphorin A also showed selective inhibition against certain human cancer cell lines.

PubMed
3

Anti-proliferation Activity of Terpenoids Isolated from Euphorbia kansui in Human Cancer Cells and Their Structure-Activity Relationship (Preclinical, 2018)

Wang HY, Wang JS, Wei DD, Wang XB, Luo J, Yang MH, Kong LY. Chin J Nat Med. 2018;16(4):284-295.

Twenty-five terpenoids were isolated from Euphorbia kansui, including two new compounds. Eighteen were tested against five human cancer cell lines. Significant anti-proliferation effects were observed in melanoma (MDA-MB-435) and colorectal cancer (Colo205) cells. More than half of the ingenane-type diterpenes showed inhibitory activity, and preliminary structure-activity relationships were established for the ingenane class.

PubMed
4

Triterpenoids, Steroids and Other Constituents from Euphorbia kansui and Their Anti-inflammatory and Anti-tumor Properties (Preclinical, 2022)

Jiang X, Liu Q, Xue S. Phytochemistry. 2022;204:113449.

Sixty-two compounds were isolated from Euphorbia kansui roots, including six new triterpenoids and two new steroidal glycosides. Notably, C21-steroidal glycosides were identified from Euphorbia plants for the first time. Several compounds showed anti-inflammatory and cytotoxic properties, expanding the known chemical diversity of this herb.

Link
5

Effect of Gancao (Glycyrrhiza) Combined with Gansui on Metabolism of Toxic Components Kansuinine A and B (Preclinical, 2015)

Zhang Y, et al. Chinese Journal of Pharmacovigilance. 2015;12(1):29-33.

This study investigated why combining Gan Sui with Gan Cao increases toxicity. Results showed that co-administration inhibited the activity of multiple CYP450 enzymes (CYP3A4, CYP2D6, CYP2C9, CYP1A2, CYP2C19) involved in metabolizing Gan Sui's toxic diterpenes (kansuinine A and B), causing these toxic compounds to accumulate in the body. Glycyrrhizic acid and glycyrrhetinic acid from Gan Cao directly inhibited the metabolism of these toxins, providing a pharmacological basis for the classical incompatibility rule.

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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.