MineralsPurgativeNatrii Sulfas Exsiccatus

Xuan Ming Fen (Weathered Sodium Sulfate)

A practical guide to Xuan Ming Fen: what it is, how Traditional Chinese Medicine uses it, the classical formulas it appears in, and who should be careful with it.

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Last reviewed Oct 29, 2026

Quick Facts

Latin Name	Natrii Sulfas Exsiccatus
Chinese Name & Pinyin	玄明粉 · Xuan Ming Fen
Medicinal Part	Minerals
The item	Xuan Ming Fen is weathered mirabilite, anhydrous sodium sulfate. Mang Xiao is not this herb. It is stirred into strained decoction, never boiled.
Nature and channels	Cold, salty, bitter. Enters the Stomach and Large Intestine. Cold salty bitter purges excess heat, moistens dryness, and softens hard masses.
Pharmacopoeia line	Clears and purges excess heat, and moistens dryness to soften hard masses. Traditionally used for dry bound stool with bloated painful abdomen, bad breath and bitter mouth, and palpable hard masses.
Pattern cues	Dry bound stool. Bloated painful abdomen. Thick yellow tongue coat. Hard masses.
In this article	Xuan Ming Fen versus Mang Xiao. Gentle weathered purging versus strong crystalline driving. Why it is stirred in rather than boiled. Why pregnancy is a caution. Who should skip it.

What Is Xuan Ming Fen?

Xuan Ming Fen (玄明粉; Xuán Míng Fěn; Latin: Natrii Sulfas Exsiccatus; English: weathered mirabilite powder, anhydrous sodium sulfate) in the current pharmacopoeia is the fine white powder left when natural mirabilite weathers and loses its water of crystallization. It is cold, salty, and bitter, enters the Stomach and Large Intestine channels, and its core actions are to clear and purge excess heat, and to moisten dryness and soften hard masses. It usually goes into prepared decoctions as a stirred-in powder. The usual amount is 3–6 g. It is not boiled with the herbs; it is stirred into the strained warm decoction, or taken stirred in a little warm water.

It is not Mang Xiao. Natural crystalline mirabilite is colder and drives downward more sharply for acute heavy stagnation; Xuan Ming Fen is the weathered, milder powder that moistens and softens while purging gently. Deficiency-cold constipation, with loose stools, cold limbs, and a pale tongue, is a poor match. Use caution in pregnancy. Prolonged use drains healthy qi. Severe abdominal pain with no stool, or signs of dehydration, need a clinic first.

It is used most often for three patterns:

Dry, bound stool with bloated painful abdomen, bad breath, thick yellow coat
Dry stool with abdominal distension and palpable hard masses
Acute heavy stagnation with high fever and restlessness — seek care

Cold, salty, and bitter, it is not a daily “bowl clearing” powder to keep stirring in. Purging when there is no excess heat drains the stomach and intestines and weakens normal function.

When excess heat and dryness accumulate in the stomach and large intestine, hard dry stool, a painful bloated belly, and a red tongue with thick yellow coat are common. Xuan Ming Fen is cold, salty, and bitter. It purges, moistens, and softens, which is why it appears in Tiao Wei Cheng Qi Tang (Regulate the Stomach and Order the Qi Decoction)–type formulas, often paired with Da Huang (Rhubarb Root) to drive downward and Gan Cao (Licorice Root) to soften the blow. It drives downward more than it holds. A cold weak gut, with no heat to purge, gets weaker if more is added.

Xuan Ming Fen is not a catch-all constipation powder. In deficiency-cold constipation, with no excess heat pattern, or in pregnancy, using it alone is a poor match. Weathered or crystalline, and whether it belongs in a formula, should be decided by a licensed Chinese medicine practitioner after pattern diagnosis.

Xuan Ming Fen: Materia Medica Profile

Identification & Quality Standard

Natrii Sulfas Exsiccatus

Botanical Origin

The refined substance obtained from mang xiao that (Na2SO4·10H2O) has undergone efflorescence dehydrated from exposure to air; it primarily consists of Na2SO4.

Production Regions

Produced in most areas of China.

Quality Requirements

Superior medicinal material has thin powder, white color, dry.

Macroscopic Features

Fine powder. White, not lustrous; opaque. Loose texture. faint odor, salty taste. Strongly absorbs moisture.

Main Regions and Quality Identification

Traditional materia medica and industry experience value the producing regions rich in mirabilite — such as several provinces in the north — but actual quality also depends on variety, harvest time, processing, and storage. Good-quality Xuan Ming Fen should be a white powder with a fine texture, no impurities, and a salty, bitter taste. The difference between the raw and the processed: mirabilite is strongly crystalline and relatively hard, while Xuan Ming Fen, after weathering, is loose in texture and dissolves easily in water. The common look-alikes are other similar white mineral powders — such as Shi Gao or Hua Shi Fen — which are harder in texture, dissolve slowly in water, and taste different from the salty-bitter Xuan Ming Fen.

Traditional Properties & Historical Lineage

Nature, Flavour & Channel Tropism

Salty, Bitter; ColdStomachLarge Intestine

1. Records in Classic Materia Medica

Shen Nong Ben Cao Jing — though it does not directly mention Xuan Ming Fen, it records Mang Xiao as "governing all diseases, removing the cold-heat evil qi, driving out the accumulations of the six bowels, resolving firm retained masses, and able to transform seventy-two kinds of stones."
Ming Yi Bie Lu: supplements that Mang Xiao has the actions of "stomach heat, aiding digestion, breaking blood blockage, resolving erosion, and benefiting the five organs."
Xin Xiu Ben Cao: mentions that Mang Xiao "treats the accumulations of the five organs, long heat with stomach closure, removes evil qi, and breaks retained blood."
Ben Cao Gang Mu: lists Xuan Ming Fen separately, saying it "purges heat, moistens dryness, softens hardness — treating excess-heat accumulation, blocked stool, and red swollen eyes."
De Pei Ben Cao: further explains that "the salty softens hard masses, the bitter drains heat, and the cold removes heat — hence it governs the above patterns."

2. How Views of Its Nature Changed

Views among physicians differ. Some early physicians merged it with Mang Xiao, leaning more to "driving accumulations and breaking retained blood"; after the Ming-Qing period, physicians gradually distinguished Xuan Ming Fen from Mang Xiao, holding that Xuan Ming Fen is purer, slightly gentler in cold, and more fit for clearing excess heat without over-harming the upright qi. Some physicians also stress that Xuan Ming Fen applies only to excess-heat dryness-accumulation — if used for deficiency-cold constipation or accumulation, it worsens the discomfort. This understanding also gave later generations a clearer definition of its scope.

Core Efficacies & Traditional Applications

Traditional Functions

Drains downward and frees stools, moistens dryness and softens hardness, clears fire and reduces swelling.

1. First Direction: Clearing and Purging Excess Heat

Traditional action: clear and purge the excess heat of the stomach and large intestine, resolving dryness-accumulation.
Typical signs: gastrointestinal excess heat from too much spicy or greasy food, or external heat evil — shown as dry, bound stool, bloating and abdominal pain, bad breath and a bitter mouth, and a red tongue with a thick yellow coating.
Usual combinations: often paired with other clearing-purging or stomach-harmonizing herbs — such as with Da Huang to strengthen the purging action, or with Zhi Shi to regulate the qi and guide stagnation — avoiding harm to the upright qi from purging alone.
Who should not self-use: for deficiency-cold constipation — shown as loose stool, fear of cold, and a pale tongue with a white coating — or for pregnant and breastfeeding women, blind use may worsen the discomfort or affect the body state.

2. Second Direction: Moistening Dryness and Softening Hard Masses

Traditional action: soften the formed hard accumulations inside, dredging the blockage.
Typical signs: dryness-accumulation formed by dryness evil combining with heat evil — such as blocked stool of gastrointestinal dryness-accumulation, or the lumps of phlegm-heat accumulation inside — shown as dry, bound stool, a full abdomen with palpable hard masses, or with a cough and yellow, sticky phlegm.
Usual combinations: often paired with the dryness-moistening or phlegm-resolving herbs — such as with Gua Lou to moisten dryness and resolve phlegm, or with Xing Ren to moisten the intestines and free the bowels.
Who should not self-use: for the accumulation of spleen-deficiency with damp-excess — shown as poor appetite, bloating, and loose stool — use would worsen the damp evil and cause discomfort.

3. Classic Pairing: Xuan Ming Fen With Da Huang

Xuan Ming Fen and Da Huang form a common pair. Da Huang's action is purging downward to attack accumulations, clearing heat and reducing fire; Xuan Ming Fen's action is moistening dryness, softening hard masses, and clearing excess heat. Combined, Da Huang's purging action works with Xuan Ming Fen's softening action, strengthening the clearing-purging of gastrointestinal excess heat and the resolution of dryness-accumulation; at the same time, Da Huang can guide Xuan Ming Fen's force directly to the intestines, avoiding the cold retention that Xuan Ming Fen alone may cause. The pairing fits the patterns of gastrointestinal excess-heat dryness-accumulation — such as blocked stool, bloating and abdominal pain, and high fever with irritability — but it must be used after the physician's pattern diagnosis, with the dose adjusted to the patient's constitution. Do not pair and take it on your own.

Modern Research

Modern research offers useful context, but Traditional Chinese Medicine prescribes on whole-pattern diagnosis rather than isolated compounds.

1. Main Chemical Constituents

Research shows that natural mirabilite mainly contains sodium sulfate decahydrate — this constituent is detected in the mineral. Xuan Ming Fen, obtained by weathering the mirabilite, mainly contains anhydrous sodium sulfate — detected in the weathered powder. In in vitro experiments, a high concentration of sodium sulfate may produce a certain stimulation of the intestinal mucosa; in animal experiments, giving rats a preparation containing Xuan Ming Fen shows faster intestinal motility. Currently, no sufficient human clinical research has established a clear dose-effect relationship.

2. Current Research Directions

Current research mainly focuses on the effects of Xuan Ming Fen on intestinal function. In experiments, the sodium sulfate it contains forms a hypertonic environment in the intestine, possibly increasing the water in the intestinal lumen — helping soften dry masses and promote bowel movement. In addition, some in vitro experiments observe effects on certain inflammatory factors — but more human studies are still needed to verify the practical significance of these actions.

3. Limitations of Current Research

Lab results are not clinical efficacy — in vitro and animal results cannot be directly equated with the effect after a person takes Xuan Ming Fen, because the human intestinal environment differs from the experimental environment.
Extracts and monomers are not the same as traditional slices — the sodium sulfate monomer used in modern research differs from the traditionally processed Xuan Ming Fen slices in purity and in the impurity residue of processing — they cannot be simply substituted.
Doses and preparation methods vary between studies — the doses and processing degrees of Xuan Ming Fen differ across experiments, so the results differ and no unified conclusion can form.
A single component does not define the whole herb — Xuan Ming Fen's action is not decided by the sodium sulfate alone; other trace substances possibly produced during processing may also affect its effect.

Comparing Similar Herbs

1. What They Share

Choosing Mang Xiao as the similar herb, the two share these points:

Both have the main actions of clearing and purging excess heat, and moistening dryness to soften hard masses.
Both are used for the traditional patterns of gastrointestinal excess-heat dryness-accumulation — such as blocked stool and bloating with abdominal pain.
Both may appear in the formulas for food accumulation or external heat evil.
Both need the constitution and dose considered — overuse harms the upright qi.

2. The Key Differences: Xuan Ming Fen vs. Mang Xiao

Nature and flavors: both are salty, bitter, and cold — but Mang Xiao is a natural mineral crystal with a relatively stronger cold; Xuan Ming Fen, after weathering, is slightly gentler in cold, looser in texture, and relatively milder in force.
Focus: Mang Xiao leans to purging downward to attack accumulations, acting directly on the discharge of the dryness-accumulation; Xuan Ming Fen leans to moistening dryness and softening hard masses, and while resolving the dryness-accumulation, can slightly temper the cold's irritation of the intestines.
Qi tendency: both belong to the purgative class, guiding the pathogenic qi to drain downward — but Mang Xiao's purging is more direct and pushes the intestinal qi more forcefully, while Xuan Ming Fen pushes the qi while also moistening dryness, reducing the irritation of the intestines.
Best fit: Mang Xiao fits the heavier dryness-accumulation with marked bloating and a thick, dry tongue coating; Xuan Ming Fen fits the milder dryness-accumulation, or cases with slight heat signs that cannot tolerate a strong purge.
Not suitable: Mang Xiao's cold is stronger — prohibited for deficiency-cold constipation and prohibited for pregnant women; Xuan Ming Fen is gentler in cold, but those with deficiency-cold constipation still need caution, pregnant women should avoid it, and the dose must be strictly controlled.
Use scenes: Mang Xiao often appears in the acute cases needing a strong purge — such as the severe bloating and blocked stool of acute gastrointestinal accumulation; Xuan Ming Fen is used more in the cases needing a mild clear-purge — such as chronic excess-heat dryness-accumulation, or as an auxiliary clearing-purging herb in formulas.

3. One-Sentence Summary

Simply put, Xuan Ming Fen leans toward mild clearing-purging, moistening dryness, and softening hard masses, whereas Mang Xiao leans toward direct purging downward, attacking accumulations, and guiding stagnation. Both can be used for gastrointestinal excess-heat dryness-accumulation, but they are not interchangeable.

Classical Formulas Containing Xuan Ming Fen

Tiao Wei Cheng Qi Tang

調胃承氣湯

Formula CategoryPurgative FormulasPrimary PatternStomach HeatPrimary FunctionMildly purge heat accumulation, harmonise the StomachRelated ConditionsConstipation·Abdominal Pain·Fever·Dry Mouth & Throat

View Formula Profile Read Complete Guide

Formulas vs. Single Herbs

A formula is many herbs acting together, achieving an overall therapeutic effect through the lord-minister-assistant-courier logic; a single herb cannot simply replicate a full formula's effect, because a single herb's action is single and cannot attend to the harmonizing, assisting, and other needs together. The doses and combinations in a formula are holistic — each herb's dose and type are carefully adjusted to fit the specific pattern. Do not build formulas from online articles, because online articles cannot reflect individual constitution and illness differences. The common misunderstanding: a herb that works in a formula does not mean taking it alone produces the same effect — a formula's overall action is the synergy of many herbs, and a single herb's action cannot replace that synergy.

Diet & Daily Home Use

1. Home Tea and Porridge

Xuan Ming Fen is a medicinal slice — it is not advised to use it directly as an ordinary food. If home regulation is needed, use it under a physician's guidance; the following examples must be strictly dose-controlled and not adjusted casually.

(1) Xuan Ming Fen Cha (Weathered-Mirabilite Tea): Xuan Ming Fen 0.5 g. Dissolve in a small amount of warm water, or blend with a little honey for taste. Suited to the blocked stool, bad breath, and bitter mouth of mild gastrointestinal excess-heat dryness-accumulation. Not for those with deficiency-cold constipation or pregnant women. Suggested: no more than once a week; do not use long-term.

(2) Xuan Ming Fen and Gua Lou Zhou (Weathered-Mirabilite Trichosanthes Porridge): Xuan Ming Fen 0.5 g, Gua Lou 10 g, Jing Mi 50 g. Decoct the Gua Lou in water first and take the juice, cook the Jing Mi into porridge with the juice, and after the porridge is done, add the Xuan Ming Fen and blend well. Suited to the dryness-accumulation with phlegm-heat — shown as dry, bound stool and a cough with yellow phlegm. Not for those with spleen-deficiency damp-excess. Suggested: once every two weeks, under a physician's guidance.

2. Decoction and Processing Differences

Xuan Ming Fen differs from other slices in decocting — it is fine in texture and dissolves easily in water; it does not need to be decocted with the other herbs and is usually taken by dissolving (flushing). The raw Xuan Ming Fen is loose after weathering; the processed, if further dried, is more even in texture — but the two differ little in action, with the main difference in fineness. For home use, do not put Xuan Ming Fen into the herb bag to decoct — after the other herbs are decocted, take the juice and dissolve the powder in it, or dissolve it directly in a small amount of warm water. Different forms cannot be converted directly — the Xuan Ming Fen dose in a prescription differs from the home-use dose; adjust to the specific situation, and do not substitute casually.

3. Dosage and Course

The common dose in traditional prescriptions is 3–6 g, for clearing and purging excess heat. The food-therapy or home-regulation dose must be smaller — usually no more than 1 g — and under a physician's guidance. The difference between the food-therapy and medicinal doses: the food-therapy dose is based on daily regulation needs — smaller and gentler — while the medicinal dose is based on treatment needs — larger and stronger. Long-term continuous use is not advised, because Xuan Ming Fen belongs to the clearing-purging class — long-term use may harm the upright qi and weaken the spleen-stomach function. Special groups — such as pregnant women, children, the elderly, and those with liver or kidney impairment — must consult a physician or pharmacist; do not decide the dose and course on your own.

Contraindications & Safety Warnings

1. Who Should Avoid It

Deficiency-cold constipation — shown as loose stool, fear of cold, and a pale tongue with a white coating — should not use it.
Pregnancy and breastfeeding — need caution; without a physician's guidance, avoid use.
Children and the elderly — weaker constitution and incomplete spleen-stomach function — use under a physician's guidance.
Liver or kidney impairment — drug metabolism may be affected — avoid self-use.
Allergy to mineral-type drugs — may have an allergic reaction to Xuan Ming Fen's constituents — need caution.
Those in special treatment — such as anticoagulant treatment or chemotherapy — consult a physician before use, to avoid drug interactions.

2. Interactions and Diet Notes

Xuan Ming Fen may interact with anticoagulants, blood-pressure medications, and glucose-lowering medications, affecting the absorption or metabolism of the drugs — patients taking these should consult a doctor or pharmacist first; do not self-use. There is no sufficient evidence of a general "food clash" between ordinary foods, but certain herbs can interact with specific drugs — those on medication should consult a doctor or pharmacist first. During the use of Xuan Ming Fen, avoid spicy and greasy food, so as not to add burden to the gastrointestinal tract and affect the drug effect; also drink more water, to avoid the dryness-accumulation worsening.

3. Adverse Reactions and Overdose Risk

Discomfort from Xuan Ming Fen may include mild abdominal pain and diarrhea; if the dose is too large, it may cause uncontrolled diarrhea, severe abdominal pain, and even dehydration. Allergy signs include rash, itching, and breathing difficulty — if these appear, stop at once and seek medical care. If marked discomfort, allergy signs, persistent vomiting, breathing difficulty, altered consciousness, or rapidly worsening symptoms appear, stop at once and seek medical care — do not handle it on your own.

Frequently Asked Questions About Xuan Ming Fen

What is Xuanmingfen? Is it the same as Mangxiao or Dahuang?

Xuanmingfen is weathered and dried sodium sulfate, mainly containing sodium sulfate, Latin name Natrii Sulfas Exsiccatus. It is a common Chinese medicine centered on draining downward to promote bowel movement, moistening dryness and softening hardness, and clearing fire to reduce swelling. Mangxiao drains downward and softens hardness. Dahuang drains downward and attacks accumulation. They cannot be used interchangeably in equal amounts. Prescribe as Xuanmingfen. Caution in pregnancy.

What are the composition and effects of Xuanmingfen?

Pharmacopoeial name Xuanmingfen, Latin sodium sulfate. Salty and bitter in taste, cold in nature, enters the Stomach and Large Intestine meridians. Functions to drain downward to promote bowel movement, moisten dryness and soften hardness, and clear fire to reduce swelling. Used for excess heat accumulation and stagnation, dry constipation, abdominal fullness and pain; externally for sore throat, mouth sores, gum swelling, red eyes, carbuncles and erysipelas. Drains downward and softens hardness.

How to choose between raw and processed? Can Mangxiao replace it?

Powder is dissolved in decoction and used raw. Mangxiao emphasizes dry constipation rather than strongly reducing swelling, and cannot replace it in equal amounts. Commercial products are standardized; do not adjust arbitrarily.

What is the dosage of Xuanmingfen? Can it be used daily as a bowel-moving tea?

Dissolved in prepared decoction, 3-9g. Modern use requires physician-determined dosage. It is not a year-round "Xuanmingfen tea." Pregnancy will be further injured by prolonged use. Constipation requires short-term, physician-determined dosage and cannot replace evaluation.

What are the contraindications of Xuanmingfen? Can pregnant women use it?

Not suitable for pregnant women. Should not be used with Liuhuang or Sanleng. Spleen-stomach deficiency cold requires physician evaluation. Stop if abdominal pain or diarrhea occur. Seek immediate medical care for severe constipation or high fever.

Can Xuanmingfen drain downward, soften hardness, and reduce swelling?

It can assist excess heat accumulation and stagnation, dry constipation, abdominal fullness and pain, sore throat, mouth sores, gum swelling, red eyes, carbuncles and erysipelas. It drains downward to promote bowel movement, moistens dryness and softens hardness, and clears fire to reduce swelling, but is not a specific remedy for all constipation or all swelling and pain.

Can Xuanmingfen be taken daily as a bowel-moving or swelling-reducing tea?

Excess heat accumulation can be used short-term in formulas; pregnancy will be further injured. The idea that "Xuanmingfen must promote bowel movement" cannot replace evaluation. Draining downward and softening hardness requires physician-determined formulation and dosage.

How to choose between Xuanmingfen, Mangxiao, Dahuang, Fanxieye, and Huomaren?

Xuanmingfen drains downward and softens hardness, suited to dry constipation. Mangxiao drains downward and softens hardness. Dahuang drains downward and attacks accumulation. Fanxieye drains heat and moves stagnation. Huomaren moistens the intestines. Choose Xuanmingfen for promoting bowel movement; Mangxiao for softening hardness; Dahuang for attacking accumulation; Fanxieye for heat accumulation; Huomaren for moistening the intestines. Pattern differentiation applies, but large doses of Xuanmingfen are contraindicated in pregnancy.

How is Xuanmingfen commonly modified? What is a representative usage?

Modifications depend on the pattern. Add Dahuang for constipation; add Bingpian for swelling and pain. Specify Xuanmingfen; do not substitute Mangxiao in equal amounts for reducing swelling.

How to select and store Xuanmingfen?

Choose regular Chinese medicinal materials with white powder. Discard if moldy, damp, or abnormal in odor. Seal to prevent moisture. Purchase "Xuanmingfen"; do not substitute Mangxiao or Dahuang in equal amounts for draining downward, softening hardness, and reducing swelling.

Related Products

Nong's Xuan Ming Fen Concentrated Granules

Nong's Xuan Ming Fen (Exsiccated Sodium Sulfate) Single Herb 1:1 Concentrated Granules $32.47

Hoi Tin Xuan Ming Fen (Weathered Sodium Sulfate) Single Herb 5:1 Concentrated Granules, 100 g TCM Herbal Supplement

Hoi Tin Xuan Ming Fen (Weathered Sodium Sulfate) Single Herb 5:1 Concentrated Granules $20.53

Nong's Tiao Wei Cheng Qi Tang Extract Granules

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Medical Disclaimer — This article is provided for educational purposes only and describes traditional Chinese medicine concepts. It is not medical advice, and it is not intended to diagnose, treat, cure or prevent any disease. Always consult a qualified practitioner before using any herb, particularly if you are pregnant, nursing, taking medication or managing a diagnosed condition.