Traditionally used for
- Eye health
- Teeth & mouth
- Digestion
- Bowel health
- Urinary & fluids
Cautions & contraindications
- Heart conditions
- Kidney conditions
☯ TCM Properties
Clears Heat, cools the Blood, improves eyesight and moistens Dryness
Traditional Chinese Uses
Da Qing Yan is halite, the natural crystalline form of rock salt (sodium chloride; Halitum), a salty, cold mineral entering the Heart, Kidney, and Bladder channels. It clears Heat and cools the Blood, brightens the eyes, and moistens Dryness. Internally, in small dose, it is used for Blood-Heat bleeding such as blood in the vomit or urine and bleeding, sore gums, for toothache, and for constipation with dry stool.
A prominent traditional use is topical: pounded to powder it is applied to red, swollen, painful eyes and eyelid-margin inflammation (as an eyewash), and used for the teeth and gums as a dentifrice or mouthwash. Typical internal dose is small (about 1.2-2.5 g), or it is made into pills or powder. As a concentrated salt it should be used sparingly and cautiously, especially where sodium restriction applies.
Relationships
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Botanical Description
Da Qing Yan (大青盐) is the Chinese materia medica name for halite, a naturally occurring crystalline form of sodium chloride (NaCl), commonly known as rock salt. It is not a plant but a mineral substance, typically harvested from salt deposits or salt lakes in northern and northwestern China. The crystals are colorless, white, blue, or pale violet, and dissolve readily in water. In traditional Chinese medicine, Da Qing Yan is classified as cold and salty, entering the Kidney, Heart, and Stomach channels. It is used to cool blood, clear heat, brighten the eyes, soften hard masses, and detoxify. Classical indications include sore swollen gums, toothache, throat soreness, and red eyes, and it appears as an ingredient in ophthalmic and dental preparations.
Active Constituents
Sodium chloride (NaCl), the mineral halite
Halide mineral; cubic sodium chlorideConcentration: Pharmacopoeia of the People's Republic of China: not less than 97.0 percent NaCl. Sodium is 39.34 percent of NaCl by mass, so the monograph dose of 1.2 to 2.5 g delivers roughly 470 to 980 mg of sodium.
Sodium is not a trace constituent here, it is the drug, and the dose is large in dietary terms. The WHO adult target is under 2,000 mg of sodium a day, so a single daily dose of Da Qing Yan supplies about a quarter to a half of the entire recommended daily sodium allowance, on top of a Chinese background intake that already runs at roughly double the WHO salt target. Everything in the interaction profile below follows from that one number: this drug's pharmacology is sodium loading, and its risks are the risks of sodium.
Potassium, magnesium and calcium chlorides and sulfates
Co-crystallised evaporite saltsConcentration: Reported impurity figures for the drug are of the order of 0.084 percent Ca2+, 0.016 percent Mg2+ and 0.25 percent sulfate, with potassium chloride, magnesium chloride, calcium chloride, magnesium sulfate and calcium sulfate all named among the accompanying salts.
These are the ordinary bitterns of a salt lake and account for the slightly bitter taste noted in the Pharmacopoeia description. At the doses used they are pharmacologically trivial next to the sodium. Their real significance is analytical: they are why the assay ceiling is 97 percent rather than 100, and they are the fraction that varies most between deposits.
Iron and included clay
Insoluble mineral inclusionsConcentration: Trace and variable; materia medica descriptions attribute the drug's characteristic bluish-grey to dark cast, and the small cavities that distinguish it from Sal Lucidum, to included clay and mineral impurity.
Insoluble and essentially inert on ingestion. They matter as identity markers rather than as pharmacology: the small pits and the blue-grey colour are the features by which Da Qing Yan is told apart from the confusable Guang Ming Yan, which is irregular, dull white and lacks the cavities.
Iodine (absent)
Micronutrient absent from the drugConcentration: None added. This is unfortified lake salt, outside China's universal salt iodisation programme, which fortifies table salt.
Recorded because the absence is easy to miss. Nothing follows from it at the 1.2 to 2.5 g medicinal dose. It matters only where patients take up qing yan as a culinary or tooth-cleaning salt in place of iodised table salt, which displaces their iodine source without replacing it.
Regulatory limits on arsenic, lead, cadmium and mercury
Quality-control status (not a chemical constituent)Concentration: None in the monograph. The Pharmacopoeia monograph for Halitum specifies a silver nitrate precipitation test, a sodium flame test and an assay of not less than 97.0 percent NaCl; it sets no limit for arsenic, lead, cadmium or mercury.
Said plainly: there is no Pharmacopoeial heavy-metal specification for this drug. ChP 2020 dropped the blanket heavy-metals provision in favour of element limits on a named list of individual medicinal materials, and mineral drugs including Halitum are not on it. In practice the risk here is lower than for most mineral drugs, because a 97 percent NaCl assay leaves only 3 percent for everything else and evaporite halite is not a metal ore; but the reassurance comes from the chemistry of the deposit, not from any test the monograph requires.
⚠ Drug Interactions
Lithium
The proximal tubule handles lithium as it handles sodium, so renal lithium clearance moves with sodium intake and with sodium balance. Raising sodium intake increases lithium clearance and lowers plasma lithium toward subtherapeutic levels; falling sodium intake, or sodium depletion from vomiting, diarrhoea, sweating or diuretics, reduces clearance and raises plasma lithium toward toxicity. Lithium's narrow therapeutic index means comparatively minor changes in plasma concentration have significant clinical consequences, which is why sodium is the classic determinant of lithium level and why diuretics remain the best-documented lithium interaction. A drug delivering 470 to 980 mg of sodium daily is a sodium intervention, and the hazard is symmetrical: starting it can push a stable patient subtherapeutic, and stopping it abruptly can push the same patient toward toxicity.
Clinical note: Avoid in patients on lithium. If it is used anyway, treat starting and stopping it as changes in sodium intake requiring a lithium level, and never stop it abruptly without one.
Antihypertensive drugs of all classes, particularly thiazide and loop diuretics, ACE inhibitors and angiotensin receptor blockers
The dose-response between salt and blood pressure is one of the best-established relationships in cardiovascular medicine and it runs in both directions. He, Li and MacGregor's Cochrane-based meta-analysis of longer-term modest salt reduction found consistent blood pressure falls in hypertensive and normotensive adults, and Zhang et al.'s more recent meta-analysis of randomised trials confirms the association between change in salt intake and change in blood pressure. Sodium loading also specifically blunts the classes that work through sodium handling and the renin-angiotensin system: diuretic natriuresis is offset by the added intake, and the antihypertensive effect of ACE inhibitors and angiotensin receptor blockers is markedly reduced on a high-sodium diet. Adding a salt drug to an antihypertensive regimen works against the drug at its own mechanism.
Clinical note: Do not prescribe to a hypertensive patient. If a patient on antihypertensives has been taking it, an unexplained loss of blood pressure control is more likely to be the salt than a failing drug, and stopping it is the first move rather than escalating therapy.
Corticosteroids, fludrocortisone and licorice (Gan Cao, glycyrrhizin)
Mineralocorticoid activity drives renal sodium retention and potassium wasting. Glycyrrhizin from licorice inhibits 11-beta-hydroxysteroid dehydrogenase type 2, letting cortisol act on the mineralocorticoid receptor and producing apparent mineralocorticoid excess — hypertension, oedema and hypokalaemia — and the same picture follows fludrocortisone and, less strongly, systemic corticosteroids. Adding sodium chloride to a patient whose kidney is already retaining sodium loads the mechanism from the substrate side. This is not a rare pairing: Gan Cao appears in a large fraction of Chinese formulas, so any formula containing both is at risk.
Clinical note: Check formulas for licorice before adding this drug, and monitor blood pressure and serum potassium if the combination is unavoidable. Hypokalaemia with new hypertension in a patient on a licorice-containing formula should prompt review of both the licorice and the salt, not just the licorice.
Diuretics and sodium restriction in heart failure, cirrhosis and chronic kidney disease
In decompensated heart failure, cirrhosis with ascites and advanced chronic kidney disease, sodium restriction is a pillar of management and the diuretic dose is titrated against sodium intake. A fixed daily sodium load of 470 to 980 mg from a herbal prescription is not a rounding error against these targets: it offsets diuresis, expands extracellular volume, and can precipitate oedema, ascites reaccumulation or pulmonary congestion. In dialysis patients it drives interdialytic weight gain and thirst.
Clinical note: Contraindicated in heart failure, cirrhosis with ascites, nephrotic syndrome and advanced chronic kidney disease. Worth asking about specifically, since the drug's own indication set — difficult urination in the classical formula Fu Ling Rong Yan Tang — steers it toward exactly these patients.
Guang Ming Yan (Sal Lucidum) and refined table salt dispensed as Da Qing Yan
Da Qing Yan is confused in practice with Guang Ming Yan (Sal Lucidum), another rock salt, and with ordinary refined table salt. The materia medica distinguishes them by habit: Da Qing Yan forms cubic to irregular multi-edged grains, blue-grey to dull white, pitted with small cavities, whereas Guang Ming Yan is irregularly blocky, uniformly dull white, and lacks the cavities. Because all three are essentially sodium chloride, substitution does not change the sodium exposure that drives every interaction above — which is the point worth making, since a practitioner who has confirmed identity has not thereby reduced any risk.
Clinical note: Verify identity for the sake of the record, but do not treat authentication as a safety measure here. Any of these materials delivers the same sodium; the clinically important question is whether the patient should be receiving sodium at all.
Calcium-containing kidney stones and thiazide stone prophylaxis
Renal sodium and calcium handling are coupled in the proximal tubule, so a sodium load increases urinary calcium excretion; this is also why a high-sodium diet blunts the hypocalciuric effect on which thiazide stone prophylaxis depends. The epidemiology is more equivocal than the physiology: Tang et al., analysing 19,405 NHANES participants of whom 1,895 had stone disease, found no independent association between dietary sodium intake alone and stone prevalence, while a higher sodium-to-potassium ratio was associated with increased odds (OR 1.30, 95 percent CI 1.10 to 1.70, highest versus lowest quartile) and higher potassium intake with reduced odds. The mechanism is sound and the outcome data mixed, which is why this is graded Possible rather than Established.
Clinical note: Relevant mainly to patients on thiazides for recurrent calcium stones, where the added sodium works directly against the drug. Ask about stone history before prescribing, particularly since the classical urinary indications of this drug overlap with stone presentations.
Dosage
| Form | Amount | Frequency | Duration | Population | Notes |
|---|---|---|---|---|---|
| decoction, or powder/pills | 1.2–2.5 g | Daily | — | — | 中国药典 2020 monograph 【大青盐】【用法与用量】1.2～2.5g；或入丸散用。外用适量，研末擦牙或水化漱口、洗目。 【注意】水肿者慎用。 【性味与归经】咸，寒。归心、肾、膀胱经。 — Matched to ChP by romanised drug name (pinyin 'Da Qing Yan' → 大青盐); the romanisation is unique across all 649 ChP monographs, and the match was cross-checked against this record's own TCM temperature. Quoted verbatim. |
Evidence Tier
Strong evidence · 4 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
2
2 verified · 0 unverified
Randomized controlled trial
1
1 verified · 0 unverified
Other clinical trial
0
Observational / case report
1
0 verified · 1 unverified
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
Effect of longer term modest salt reduction on blood pressure: Cochrane systematic review and meta-analysis of randomised trials
Cochrane-based systematic review and meta-analysis of randomised trials of modest, sustained reductions in salt intake in adults. Reducing salt lowered blood pressure in both hypertensive and normotensive participants, with the fall in systolic pressure larger in hypertensive individuals, and the authors argue the effect is large enough to be expected to translate into reduced cardiovascular events at population level. Read in the other direction — which is the direction that matters for a salt drug — it quantifies what a sustained addition of salt does to blood pressure.
Association Between Changes in Salt Intake and Blood Pressure: A Systematic Review and Meta-Analysis of Randomized Controlled Trials
Recent systematic review and meta-analysis of randomised controlled trials examining the relationship between change in salt intake and change in blood pressure, updating the evidence base underlying salt-reduction guidance. Cited here as current confirmation that the salt–blood pressure relationship in randomised trials is a dose-response one, which is the basis for treating a fixed daily sodium chloride prescription as a blood pressure intervention.
Effect of Salt Substitution on Cardiovascular Events and Death
Open-label cluster-randomised trial in 600 rural Chinese villages, 20,995 participants with prior stroke or aged 60 and over with high blood pressure, mean follow-up 4.74 years. Replacing regular salt with a 75 percent sodium chloride, 25 percent potassium chloride substitute reduced stroke (29.14 versus 33.65 events per 1000 person-years; rate ratio 0.86, 95 percent CI 0.77 to 0.96), major cardiovascular events (rate ratio 0.87, 95 percent CI 0.80 to 0.94) and death from any cause (rate ratio 0.88, 95 percent CI 0.82 to 0.95), without a significant excess of serious hyperkalaemia. Included because it is the hard-outcome evidence, in the same population that uses this drug, that changes in sodium intake of the magnitude a herbal prescription can deliver translate into strokes and deaths rather than only into millimetres of mercury.
Dietary Sodium and Potassium Intakes and Kidney Stone Prevalence: The National Health and Nutrition Examination Survey 2011–2018
Cross-sectional analysis of 19,405 NHANES 2011–2018 participants, 1,895 with kidney stone disease. Dietary sodium intake alone showed no independent association with stone prevalence, either continuously (OR 0.99, 95 percent CI 0.99 to 1.00) or comparing highest with lowest quartile (OR 0.84, 95 percent CI 0.68 to 1.04). Higher potassium intake was associated with reduced odds (highest versus lowest quartile OR 0.75, 95 percent CI 0.60 to 0.94), and a higher sodium-to-potassium ratio with increased odds (OR 1.30, 95 percent CI 1.10 to 1.70). Included as the honest counterweight to the hypercalciuria mechanism: the physiology predicts a stone risk from sodium loading that this survey did not detect for sodium considered on its own.
⚠ Safety & Contraindications
- Heart conditions
- Kidney conditions
Contraindications
Its use is prohibited in patients with edema.
Source: Xi S, Gong Y. Essentials of Chinese Materia Medica and Medical Formulas. Academic Press/Elsevier, 2017, p. 85.
Historical Texts
Shen Nong Ben Cao Jing (Divine Husbandman's Classic of Materia Medica), jade-and-stone section, lower grade, under the name Rong Yan (戎盐)
Eastern Han, compiled by c. 200 CEMing Yi Bie Lu (Miscellaneous Records of Famous Physicians)
Six Dynasties, c. 500 CEBen Cao Jing Ji Zhu (Collected Commentaries on the Classic of Materia Medica), Tao Hongjing
Southern dynasties, c. 500 CEJin Gui Yao Lue (Essentials from the Golden Cabinet), Zhang Zhongjing — Fu Ling Rong Yan Tang
Han dynasty, c. 200–210 CEPharmacopoeia of the People's Republic of China, monograph for Halitum
Modern, current editionReferences
- Finley PR. Drug Interactions with Lithium: An Update . Clinical Pharmacokinetics (2016) [DOI]
- Shi J, Yang Y, Zhou X, Zhao L, Li X, Yusuf A, Hosseini MSMZ, Sefidkon F, et al.. The current status of old traditional medicine introduced from Persia to China . Frontiers in Pharmacology (2022) [DOI]
- Dai M, Wang D. Mineral medicines of the East: an analysis of records in historical Chinese and Japanese medical texts . Frontiers in Pharmacology (2025) [DOI]
- Inada I, Kiuchi F, Urushihara H. Comparison of Regulations for Arsenic and Heavy Metals in Herbal Medicines Using Pharmacopoeias of Nine Counties/Regions . Therapeutic Innovation & Regulatory Science (2023) [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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