Po Xiao

Chinese Herb Actions

Chinese Herb Dosage

• What is the dosage of Po Xiao?

  Our record gives no internal dose for Po Xiao and refers the reader to Mang Xiao, the refined grade. That is the honest position and we are not going to invent a figure: the published dose ranges for this mineral are stated for the purified material, while our own entry confines the crude grade to external application for swellings and nodules. No internal dosage is therefore given here.

  • What the refined grade is recorded at — roughly 3–9 g, and up to 9–12 g within a formula, dissolved into the strained decoction after it comes off the heat rather than boiled with the other herbs. Boiling degrades the softening action. That figure belongs to Mang Xiao, and is given here only so readers understand the scale involved.
  • External use — applied as a powder or dissolved compress over the affected area, in quantities separate from and unrelated to any internal dose.
  • Why the grade matters to the figure — the mirabilite family is graded by degree of refining, and the grades are not interchangeable by weight or by route. A dose written for one is not a dose for another.

  Source: Sacred Lotus sources & references (this herb's recorded deferral to Mang Xiao and its topical-only note, and the recorded dose range and dissolve-don't-decoct rule held on the Mang Xiao entry). Reference only — not a prescription.

Chinese Herb Contraindications & Cautions

• Are there cautions for Po Xiao?

  Yes, and the first one comes from our own records: Po Xiao is recorded as antagonised by Liu Huang (sulphur), one of the classical incompatible pairings. Beyond that, our entry's own reason for restricting this grade to external use — impurities and possible contamination in unrefined material — is itself the principal caution attached to it.

  • Recorded incompatibility — our herb-pairing data holds Liu Huang (sulphur) as antagonising Po Xiao. The Pharmacopoeia of the People's Republic of China carries the same restriction for mirabilite, stating that it should not be used with sulphur or with Bolboschoenus yagara, and that pregnant women should be cautious about using it (reported in PMID 38239194).
  • Pregnancy — the mirabilite group is a cold, strongly downward-draining mineral purgative. Our own Mang Xiao entry records it as contraindicated throughout pregnancy, and as avoided during menstruation and postpartum without qualified supervision. The same class caution applies here.
  • Deficiency-cold digestive patterns — avoid. The material is cold and draining, and will aggravate Spleen and Stomach deficiency-cold.
  • Grade restriction — our record confines this unrefined grade to external application. Readers meeting it should understand that the internal purgative literature for this mineral describes the purified grade, not this one.
  • Professional supervision — a mineral purgative with a narrow appropriate-use window is not a self-directed remedy.

  Source: Sacred Lotus sources & references (the recorded Liu Huang antagonism for this herb, this herb's topical-only note, and the recorded pregnancy and deficiency-cold cautions held on the Mang Xiao entry); Pharmacopoeia restriction as reported in PMID 38239194, PMC 10794775. Neutral reference disclosures, not usage instructions.

Chinese Herb Toxicity & Overdose

• Is Po Xiao toxic? How pure is the crude mineral?

  Our record does not flag Po Xiao as toxic, and the 2024 review of this mineral states plainly that its chemical composition is not itself toxic — but it also states that only a few toxicological studies of the material exist at all. That is the honest scale of what is documented, and it is worth stating precisely rather than filling the gap with general claims about mineral medicines.

  • What is documented for this material. The review reports that external application can leave local skin flushed or itchy; that oral administration has been shown toxic to neuromuscular cells, with a 30% sodium sulfate solution causing calcium efflux and potassium influx in those cells in the cited experimental work; and that sulfur ions arising from metabolism of the sulfate can be absorbed by digestive-tract epithelium and disturb oxidative metabolism. It also notes that no pharmacokinetic study of this mineral as a single agent has been carried out (PMID 38239194).
  • On purity — what has actually been measured. A market survey reported within that review, covering mirabilite purchased across China and analysed by X-ray diffraction, X-ray fluorescence and heating analysis, found the main component to be sodium sulfate at 88–96%, with traces of potassium, calcium, iron, copper, zinc, bromine and strontium, and magnesium very low at 300–700 parts per million. That is a purity measurement for the mineral group, not for the crude grade specifically.
  • What we are not saying. No market survey or elemental assay specific to the crude Po Xiao grade was located, so none is cited, and we assert neither that it is contaminated nor that it is clean. Our own record's statement that this grade carries impurities and possible contamination is a traditional materia medica position, and it is recorded here as such.
  • The class-level context. A 2022 review of mineral drugs in Chinese medicine states that the safety of the class “is controversial owing to their heavy metals and strong toxicity” (PMID 35144660, PMC 8830990). That is a description of the debate around mineral medicinals as a category and a legitimate reason to ask the question. It is not a measurement of what any batch of this mineral contains.

  Source: Sacred Lotus sources & references (this herb's recorded impurity note and the absence of a toxicity flag, as held on file); material-specific toxicology and the market purity survey per PMID 38239194, PMC 10794775, DOI 10.3389/fphar.2023.1293097; class-level context per PMID 35144660, PMC 8830990. Neutral reference facts — not a safety guarantee.

Herb-Drug Interactions

• Does Po Xiao interact with medications?

  No clinical herb–drug interaction study for this material could be located, and the 2024 review notes that no pharmacokinetic study of it as a single agent has been performed (PMID 38239194). What can reasonably be flagged is mechanistic rather than measured: this is a sodium salt acting as an osmotic purgative, so practitioner awareness is sensible for anyone on diuretics or other medicines affecting fluid and electrolyte balance, anyone on a sodium-restricted regimen, and anyone with renal impairment.

  • This is inference from composition and mechanism, not a demonstrated interaction. No study of this mineral co-administered with any drug was found.
  • The recorded incompatibility is herb-to-herb, not herb-to-drug — the sulphur pairing noted in our cautions is a classical materia medica restriction, not a pharmaceutical interaction finding.

  (Precautionary, based on constituent class; flagged for practitioner confirmation.)

Western / Biomedical Research

Chinese Herb Clinical Studies & Research

Provided as research context — a summary of published biomedical study, not a therapeutic or medical claim.

• Is there modern research on Po Xiao (crude mirabilite, sodium sulfate)?

  There is a real research literature on mirabilite, but almost none of it separates the crude grade from the refined one — and the exceptions are small animal studies reported at second hand. The anchor source is a 2024 review in Frontiers in Pharmacology that assembles the mineral's history, processing, chemistry, pharmacology, toxicology and clinical use in one place (PMID 38239194; PMC 10794775; DOI 10.3389/fphar.2023.1293097).

  • Where the grades were actually compared — the review tabulates mouse small-intestine propulsion experiments in which crude mirabilite, refined mirabilite and the weathered powder were tested side by side, reporting that all three increased intestinal movement relative to saline. These are small animal studies from the Chinese-language literature, summarised within the review rather than independently verifiable here, and they are reported as such.
  • Distinguishing the minerals analytically — work cited in the same review used elemental profiling to separate refined mirabilite, the crude grade and saltpetre, which is the practical answer to the naming confusion described in our notes.
  • What the mineral does pharmacologically — the review summarises anti-inflammatory effects (reduced IL-6, TNF-α and nitric oxide levels), promotion of wound healing via TGF-β1 and VEGF-A, and increased gastrointestinal motility through vasoactive intestinal peptide, substance P and motilin release. It records use across nine Chinese ethnic-medicine traditions and more than two thousand years of documented medicinal use.
  • Cholesterol handling — a 2024 mouse study found sodium sulfate reduced hypercholesterolaemia by upregulating hepatic Cyp7a1 and eased hepatic insulin resistance by downregulating Trib3 (PMID 39071912; PMC 11273247; DOI 10.3892/etm.2024.12650). Preclinical mechanism, not a treatment claim.

  Honest summary: the modern evidence describes the mineral as a family. It supports the external anti-inflammatory and the motility-promoting uses more directly than it tests any grade-specific claim, and nothing in it establishes that the crude grade behaves differently from the refined one in a human being.

  Sources: PMID 38239194, PMC 10794775, DOI 10.3389/fphar.2023.1293097 (mirabilite chemistry, processing, pharmacology, toxicology and clinical review, and the source of the grade-comparison and elemental-profiling summaries); PMID 39071912, PMC 11273247, DOI 10.3892/etm.2024.12650 (sodium sulfate, cholesterol and hepatic insulin resistance in mice); PMID 35144660, PMC 8830990 (mineral drugs in Chinese medicine, class-level review). Research context, not a therapeutic claim.

Chinese Herb Notes

• What is the difference between Po Xiao, Mang Xiao and Yuan Ming Fen?

  They are the same mineral at three stages of refining, not three different substances. All three are sodium sulfate. What separates them is how much processing the raw mineral has had, and each stage is recorded on this site as its own entry. This is the single most confusing point in the group and it is worth setting out plainly.

  • Po Xiao — the crude stage. The mined mineral, or the first coarse crystallisation from it, before purification. Our record holds it as Sal Glauberis, salty, bitter, cold, Lung/Stomach/Large Intestine, and restricts it to external use for swellings and nodules because of impurities. A 2024 review describes the modern route in the same order: natural mirabilite is dissolved in hot water, filtered, and cooled so crystals precipitate — the coarse product of that step being known as Pixiao (PMID 38239194).
  • Mang Xiao — the purified, crystallised stage. Our record holds it as Natrii Sulfas, salty, bitter and very cold, Stomach and Large Intestine. The review records that since the Ming dynasty the mainstream refining method has been boiling the crude crystals with radish and cooling the liquid to yield the purified crystal (PMID 38239194). This is the grade used as a purgative in classical formulas.
  • Yuan Ming Fen — the weathered, dehydrated stage. Our record holds it as an exsiccated sodium sulfate, and describes it as the most refined form, used most often topically for sore throat, eye disorders and mouth ulcers, and weaker than Mang Xiao at clearing heat and at purging. The review describes the same step: mirabilite left to weather loses its water of crystallisation and becomes a dry white powder, named as Xuanming powder, with Ben Cao Meng Quan (AD 1565) recording the name Yuanming powder for the material prepared without an excipient (PMID 38239194).

  The short version: crude and dirty → purified and purgative → dried, powdered and gentle. Strength of purgation falls as refinement rises; suitability for delicate surfaces such as the throat and eyes rises with it.

  Is Po Xiao the same as Ya Xiao or saltpetre?

  No — and this is a genuine trap. Po Xiao is a sulfate. Saltpetre is a nitrate, an entirely different mineral, and our site holds it separately as Ya Xiao (Nitrum). The two have been confused for centuries because their Chinese names share the same character for a crystalline salt.

  Naming conflict flagged, not resolved: the 2024 review lists Yaxiao among the historical alternative names for mirabilite (PMID 38239194), while our own separate Ya Xiao record holds Nitrum — saltpetre, a potassium nitrate. Both positions are defensible in their own literature: the same name has been applied to two chemically distinct minerals in different periods and texts. We record the conflict rather than silently picking a side, and analytical work cited in the same review distinguishes mirabilite, crude mirabilite and saltpetre by elemental profile precisely because the names alone do not.

  Identity gaps flagged, not filled: our record for this herb carries no Chinese characters, no common English name and no listed alternative names, and its Latin field reads Sal Glauberis — a chemical/pharmaceutical designation for Glauber's salt rather than a pharmacopoeial drug heading of the kind used for the refined grade (Natrii Sulfas). The record is otherwise consistent with the crude grade. We have left every field exactly as held; whether to complete them is an owner decision.

  Formula context: our own formula records link no formula to this crude grade — the purgative formulas in our collection specify the refined material — so no formula is named here.

  Source: Sacred Lotus sources & references (the Po Xiao, Mang Xiao, Yuan Ming Fen and Ya Xiao records — Latin, nature, flavour, channels, category and recorded notes — as held on file, and the absence of any formula link for this grade); refining sequence, historical names and analytical distinction per PMID 38239194, PMC 10794775. Reference facts, not preparation instructions.

This herb antagonizes or is antagonized by:

• Liu Huang (Sulphur)