Mang Xiao
StarNa₂SO₄·10H₂O (hydrated sodium sulfate, mineral mirabilite)
Traditionally used for
- Eye health
- Bowel health
- Menstrual & women's health
Cautions & contraindications
- Pregnancy
- Breastfeeding
- Heart conditions
- Kidney conditions
☯ TCM Properties
Purges Heat and Unblocks the Bowels; Softens Hardness and Moistens Dryness; Clears Heat and Reduces Swelling
Traditional Chinese Uses
Mang Xiao (sodium sulfate, mirabilite) is a very cold, salty, bitter mineral substance used primarily as a laxative for constipation caused by excess heat and dryness in the Intestines. It softens hard stools and promotes their passage, making it particularly effective for dry, difficult-to-pass stools with heat signs. It also clears heat and reduces swellings when applied topically, and is used for conditions such as mastitis, eye inflammation, and oral ulcers.
Used In Formulas (31)
Relationships
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Botanical Description
Mang Xiao is mirabilite, the naturally occurring hydrated form of sodium sulfate with the chemical formula Na2SO4 . 10H2O, also known as Glauber's salt. It is a saline mineral that crystallizes in the monoclinic system, forming colorless to white, transparent to translucent prismatic or tabular crystals, often occurring as efflorescent crusts or as compact, granular, or fibrous masses on the floors and walls of saline lakes, playas, and salt-bearing strata, particularly in arid regions of northern China. Freshly prepared crystals are glassy and brittle, with a cooling, bitter-salty taste; on exposure to dry air they readily lose water of crystallization and effloresce to a white powder (thenardite). For TCM use, the crude crystals are purified by recrystallization. Mang Xiao is classified as a salty, bitter, very cold mineral substance that drains downward and softens hardness.
Active Constituents
Sodium sulfate decahydrate
Sulfate mineral (mirabilite)Concentration: Dominant phase of the refined drug
The sulfate anion is very poorly absorbed from the gut and holds water osmotically in the lumen, which is the whole basis of the purgative action. Retained fluid distends the bowel and triggers release of vasoactive intestinal peptide, substance P and motilin, adding a motility component to the osmotic one.
Water of crystallisation
Structural (lattice) waterConcentration: 10 mol per mol Na2SO4, about 55.9% by mass
More than half the weight of Mang Xiao is lattice water, so a gram of the decahydrate carries less than half the sulfate of a gram of the anhydrous salt. The crystals effloresce in dry air to the anhydrous powder sold as Xuan Ming Fen, which is therefore roughly twice as strong per gram; treating the two as interchangeable by weight overdoses the patient.
Sodium
Alkali metal cation of the parent saltConcentration: About 14.3% of the decahydrate by mass; a 10 g dose carries roughly 1.4 g of sodium
A therapeutic dose delivers a sodium load comparable to several grams of table salt. Most of it stays in the lumen with the sulfate and leaves in the stool, but the fraction absorbed is clinically material in heart failure, cirrhosis, chronic kidney disease and poorly controlled hypertension.
Sodium chloride, magnesium sulfate and calcium sulfate
Accessory soluble salt impuritiesConcentration: Small amounts; varies with deposit and refining
Co-crystallised evaporite salts carried through refining. Magnesium sulfate is itself an osmotic cathartic, so this fraction adds to rather than dilutes the purgative effect.
Potassium, calcium, iron, copper, zinc, bromine and strontium
Trace elementsConcentration: Trace; the more abundant of the minor elements reported in medicinal mirabilite
Reported consistently across analyses of medicinal-grade mirabilite. No individual therapeutic role has been demonstrated for any of them in this drug; they are best read as a fingerprint of the source deposit.
Lithium, beryllium, chromium, cobalt, nickel, gallium, selenium, rubidium, caesium and titanium
Lower-abundance trace elementsConcentration: Below the levels of the elements above
Detected at low levels in medicinal mirabilite. Beryllium, chromium, cobalt and nickel are toxicologically significant elements, so their presence is a reason to source from characterised deposits rather than a reason to attribute activity to them.
Arsenic, lead and cadmium
Heavy metal contaminantsConcentration: Deposit- and grade-dependent; substantially higher in industrial-grade sodium sulfate
The reason medicinal and industrial mirabilite are not interchangeable. Industrial salt cake is produced for glass and detergent manufacture with no limits on toxic elements, and near-infrared methods have been developed specifically to tell the two grades apart because visual inspection cannot.
⚠ Drug Interactions
Industrial-grade sodium sulfate (salt cake, Glauber's salt)
Medicinal and industrial mirabilite are the same compound at very different purities, and the industrial grade is far cheaper. The two cannot be distinguished by appearance, which is why intelligent-sensing and near-infrared machine-learning methods have been developed for the purpose. Substitution exposes the patient to whatever arsenic, lead and cadmium the industrial process left behind, at purgative doses given repeatedly.
Clinical note: Buy Mang Xiao only against a certificate of analysis with heavy metal figures, from a supplier who sells pharmacopoeial grade. Price well below the market is the practical warning sign.
Nitrum (Xiao Shi, potassium nitrate)
Both drugs are historically called xiao and both are white efflorescent crystalline salts, and the materia medica literature from Tao Hongjing onward records repeated confusion between them. They are not pharmacologically similar: Mang Xiao is an osmotic cathartic with no systemic oxidant action, whereas Xiao Shi is potassium nitrate, which after gut reduction to nitrite oxidises haemoglobin to methaemoglobin. A case report describes rapid-onset methaemoglobinaemia in a 14-year-old after ingesting a traditional potassium nitrate preparation, with an oxygen saturation of 58% against a normal arterial oxygen tension.
Clinical note: Never accept a consignment labelled only xiao. Potassium nitrate deflagrates when a sample is dropped on a flame and sodium sulfate does not; this is the classical distinguishing test and it still works. If a patient on a purgative formula turns cyanotic with chocolate-coloured blood and a normal PaO2, suspect a nitrate substitution and treat for methaemoglobinaemia.
Digoxin, warfarin, oral contraceptives and other narrow-therapeutic-index oral drugs
Osmotic catharsis shortens intestinal transit and reduces the time available for absorption of anything taken with it. This is a general and well-documented property of saline cathartics, though no trial has quantified it for mirabilite specifically. Purgation-induced potassium loss additionally sensitises the myocardium to digoxin.
Clinical note: Do not give a purgative formula in the same window as a narrow-therapeutic-index oral drug, and warn women using oral contraceptives that a strong purge may compromise them. Keep the course short.
Loop and thiazide diuretics, corticosteroids and other potassium-wasting drugs
Saline purgation loses potassium and water into the stool; loop and thiazide diuretics and corticosteroids lose potassium into the urine. The effects add, and the elderly and those already on a low-potassium diet reach a symptomatic deficit fastest. The osmotic pull of the sulfate also moves free water into the lumen and can precipitate hypovolaemia in a patient already diuresed.
Clinical note: Check potassium and renal function before and during a course in anyone on a diuretic or a corticosteroid. Do not run repeated purgative courses in frail or dehydrated patients.
Antihypertensive, heart failure and cirrhosis regimens (sodium loading)
The decahydrate is about 14.3% sodium by mass, so a 10 g dose introduces roughly 1.4 g of sodium, equivalent to about 3.6 g of salt, into a patient who may be on a formal sodium restriction. Even with most of it passing through unabsorbed, this is an avoidable load in decompensated heart failure, ascitic cirrhosis and advanced chronic kidney disease.
Clinical note: Avoid Mang Xiao in patients under sodium restriction, and prefer a non-sodium purgative where one will do. Where it is genuinely needed, use the shortest course and monitor weight and oedema.
Sulphur (Liu Huang) and Bolboschoenus yagara
Classical incompatibility pairings. Experimental work summarised in a review of mirabilite found that combining it with sulphur or with Bolboschoenus yagara reduced its anti-inflammatory, analgesic and purgative effects without producing toxic effects, so the traditional caution appears to be about loss of action, not about harm.
Clinical note: Expect a weaker purge if these are combined; do not increase the mirabilite dose to compensate, and separate the drugs instead.
Pregnancy (obstetric contraindication rather than a drug pairing)
Strong saline purgation causes reflex uterine irritability, and mirabilite is contraindicated or restricted in pregnancy in Chinese materia medica and in the modern review literature. The evidence is traditional and precautionary rather than trial-based, but the direction is consistent and the downside is severe.
Clinical note: Do not prescribe Mang Xiao internally in pregnancy. Note that external abdominal application, which is what most of the modern clinical evidence covers, has been used peripartum for breast engorgement, but internal purgation and external fomentation are different exposures and should not be reasoned about together.
Dosage
| Form | Amount | Frequency | Duration | Population | Notes |
|---|---|---|---|---|---|
| decoction | 6–12 g | Daily | — | — | 中国药典 2020 【用法与用量】6～12g，一般不入煎剂，待汤剂煎得后，溶入汤液中服用。外用适量。 【注意】孕妇慎用；不宜与硫黄、三棱同用。 【性味与归经】咸、苦，寒。归胃、大肠经。 — Chinese Pharmacopoeia 2020, quoted verbatim; route and cautions preserved. Replaces a cleared category-filler value. |
Dui Yao — Herb Pairs
The classical two-herb combinations this herb appears in, each with an action neither herb has alone.
Bitter-cold purging combined with salty softening: together they break up hardened dry stool and drain accumulated heat from the Yang Ming organ far more forcefully than either alone.
Yang Ming fu-organ excess with dry hard stool, abdominal fullness and pain. Contraindicated in pregnancy and in deficiency.
Core pair of a classical formula — Da Cheng Qi Tang, Shang Han Lun (Zhang Zhongjing)
Evidence Tier
Moderate evidence · 6 studiesRecorded studies by study design, strongest design at the top. This is a study-design tier only, not a GRADE rating: it does not weigh risk of bias, consistency or precision.
Systematic review / meta-analysis
0
Randomized controlled trial
2
1 verified · 1 unverified
Show 2 studies
- External use of mirabilite to prevent post-endoscopic retrograde cholangiopancreatography pancreatitis in children: A multicenter randomized controlled trial
- The clinical efficacy of external application of mirabilite and rhubarb combined with intrathoracic chemotherapy in treating malignant pleural effusion
Other clinical trial
0
Observational / case report
4
2 verified · 2 unverified
Show 4 studies
- External application of mirabilite before surgery can reduce the inflammatory response and accelerate recovery in mild acute biliary pancreatitis
- Potential benefit of mirabilite external dressing combined with abdominal drainage in the early stage of severe acute pancreatitis
- Evaluation of the nursing effect of mirabilite fomentation on postoperative edema, pain, and urinary retention in patients with mixed hemorrhoids
- External use of Mirabilite combined with Lactulose improves postoperative gastrointestinal mobility among older patients undergoing abdominal surgery
In vitro / animal
0
Other / unclassified
0
Verified: design read from PubMed for a DOI that resolves to the cited paper Unverified: taken from the study's recorded description
Clinical Studies
External use of mirabilite to prevent post-endoscopic retrograde cholangiopancreatography pancreatitis in children: A multicenter randomized controlled trial
234 children with chronic pancreatitis undergoing ERCP were randomised to a bag of mirabilite applied over the pancreatic projection within 30 minutes before the procedure, or to no application. Post-ERCP pancreatitis occurred in 7.7% versus 26.5% (P less than 0.001), with lower severity, lower 24-hour pain scores, lower TNF-alpha and higher IL-10. No adverse effects of mirabilite were observed. This is external application, not oral purgation, and the control arm was untreated rather than sham.
External application of mirabilite before surgery can reduce the inflammatory response and accelerate recovery in mild acute biliary pancreatitis
Retrospective review of 75 patients having laparoscopic cholecystectomy for mild acute biliary pancreatitis, 38 given preoperative external mirabilite. The mirabilite group had faster falls in white cell count and CRP, earlier flatus, fewer thickened gallbladder walls, lower adhesion scores, and shorter waiting, operative and hospital times. Retrospective and single-centre, so allocation was not randomised and the effect size should be treated as provisional.
Potential benefit of mirabilite external dressing combined with abdominal drainage in the early stage of severe acute pancreatitis
Two-centre retrospective comparison of combined external mirabilite dressing plus abdominal drainage (n=24) against mirabilite alone (n=31) or drainage alone (n=25) in severe acute pancreatitis. The combined group reached pain relief, flatus and white-cell normalisation sooner, had the lowest intra-abdominal pressure at discharge and greater reduction in exudate area, with no difference in complications or cost. The authors describe the findings as hypothesis-generating and needing prospective validation.
Evaluation of the nursing effect of mirabilite fomentation on postoperative edema, pain, and urinary retention in patients with mixed hemorrhoids
Retrospective cohort of 121 patients after surgery for circumferential mixed haemorrhoids, propensity-score matched to 36 per arm. Mirabilite fomentation was associated with less bleeding and oedema, lower pain scores, less urinary retention (11.1% versus 30.6%, P=0.044), faster first urination and shorter wound healing (14.5 versus 17.1 days). No severe adverse reactions in either arm. Retrospective and unblinded, with outcomes assessed by the treating nursing staff.
External use of Mirabilite combined with Lactulose improves postoperative gastrointestinal mobility among older patients undergoing abdominal surgery
Observational study in older patients after abdominal surgery. Adding external mirabilite to lactulose was associated with better postoperative gastrointestinal motility and shorter hospital stay than lactulose alone. Observational rather than randomised, and the mirabilite arm also received lactulose, so the mineral's independent contribution is not isolated.
The clinical efficacy of external application of mirabilite and rhubarb combined with intrathoracic chemotherapy in treating malignant pleural effusion
Prospective randomised controlled trial of external mirabilite with rhubarb added to intrathoracic chemotherapy for malignant pleural effusion. Tests the two-mineral-and-herb external pack as an adjunct, so it does not isolate mirabilite, and the outcome is symptomatic and effusion control rather than survival.
⚠ Safety & Contraindications
- Pregnancy
- Breastfeeding
- Heart conditions
- Kidney conditions
Contraindications
Its use is cautious or prohibited in pregnant women or women in the lactation period. It is not suited to combine with sulfur ( liu huang ) or Rhizoma Sparganii ( san leng ) to use.
Source: Xi S, Gong Y. Essentials of Chinese Materia Medica and Medical Formulas. Academic Press/Elsevier, 2017, pp. 91–92.
⚠ Rule-Based Cautions
These entries come from the deterministic rule tables that gate Verscienta's formula tools — classical pair prohibitions, pregnancy and lactation contraindications, and dose ceilings.
Incompatibilities (十八反 / 十九畏)
- 十九畏: San Leng × Xiao — avoid combining with San Leng / Sparganium
- 十九畏: Liu Huang × Po Xiao — avoid combining with Liu Huang / Sulfur / Sulphur
Pregnancy
Avoid strong purgative
Historical Texts
Shen Nong Ben Cao Jing
Han dynasty, compiled c. 200 BCE to 200 CEShang Han Lun (Zhang Zhongjing)
Eastern Han, c. 200 to 210 CEBen Cao Gang Mu (Li Shizhen)
Ming dynasty, completed 1578, first printed 1596Jing Zhu Ben Cao (Dimar Tenzin Phuntsok)
Tibetan materia medica, 18th century, c. 1736 to 1796References
- Tao Lianbo; Fu Jiaqing; Wang Fangjie; Song Yinglian; Li Yi; Zhang Jingwen; Wang Zhang. The application of mirabilite in traditional Chinese medicine and its chemical constituents, processing methods, pharmacology, toxicology and clinical research . Frontiers in Pharmacology (2024) [DOI]
- Tao Lianbo; Fu Jiaqing; Wang Fangjie; Song Yinglian; Li Yi; Zhang Jingwen; Wang Zhang. Correction: The application of mirabilite in traditional Chinese medicine and its chemical constituents, processing methods, pharmacology, toxicology and clinical research . Frontiers in Pharmacology (2026) [DOI]
- Li Liang-quan; Xia Jie; Yan Rui-yang; Guo Qiang; Zhang Jiu-Ba; Li Yu; Dong Wen-hao; Zhu Wen-hong; Yu He-rong; Lu Hao-yang; Xiao Lu-qiao; Mao Chun-qin. Rapid discrimination of medicinal and industrial mirabilite based on intelligent sensing, near-infrared spectroscopy, and machine learning . Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy (2026) [DOI]
- Dai Min; Wang Ding. Mineral medicines of the East: an analysis of records in historical Chinese and Japanese medical texts . Frontiers in Pharmacology (2025) [DOI]
This information is for educational purposes only and is not intended to replace professional medical advice. Always consult a qualified healthcare provider before using any herbal remedy, especially if you are pregnant, nursing, or taking medications.
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