Magnesium sulfate

INS 518CAS 10034-99-8

Listed as an acidity regulator and a flavour enhancer by Canada, the US and Codex.

Listed as acidity regulators (CA, US) · flavour enhancers (US, Codex) · emulsifiers (US) · thickeners (US) · stabilisers (US) · anticaking agents (US) · firming agents (Codex) · nutrient supplements (US) · formulation aids (US) · lubricants and release agents (US) · starch-modifying agents (CA) · processing aids (US)
Chemical structure of Magnesium sulfate, from PubChem compound 24843
Structure from PubChem CID 24843 (National Library of Medicine, public domain). A depiction of one compound: where a listing covers a family, or a substance has no single structure, this page shows none.

Magnesium sulfate, better known as Epsom salt, is used in food as a firming agent, a nutrient source and to adjust water for brewing.

Where it is and isn’t permitted

Status of Magnesium sulfate by jurisdiction. Every jurisdiction this site covers is listed, including those where the substance does not appear.
JurisdictionStatusScope and limitsCitation
Australia and New ZealandFood Standards Australia New ZealandPermitted, with conditions

54 food categories

no numerical limit (good manufacturing practice)

Show every food category
  • 0 Preparations of food additives — GMP
  • 1.1.1 Liquid milk (including buttermilk) — GMPOnly UHT goats milk.
  • 1.1.2 Liquid milk products and flavoured liquid milk — GMP
  • 1.2.2 Fermented milk products and rennetted milk products — GMP
  • 1.3 Condensed milk and evaporated milk — GMP
  • 1.4.1 Cream, reduced cream and light cream — GMPOnly UHT creams and creams receiving equivalent or greater heat treatments.
  • 1.4.2 Cream products (flavoured, whipped, thickened, sour cream etc) — GMP
  • 1.5 Dried milk, milk powder, cream powder — GMP
  • 1.6 Cheese and cheese products — GMP
  • 10.2 Liquid egg products — GMP
  • 10.3 Frozen egg products — GMP
  • 10.4 Dried or heat coagulated egg products — GMP
  • 11.1.1 Rainbow sugar — GMP
  • 11.3.1 Dried honey — GMP
  • 11.4 Tabletop sweeteners — GMP
  • 12.1.2 Reduced sodium salt mixture — GMP
  • 12.1.3 Salt substitute — GMP
  • 12.5 Yeast and yeast products — GMP
  • 12.6 Vegetable protein products — GMP
  • 13.3 Formulated meal replacements and formulated supplementary foods — GMP
  • 13.4 Formulated supplementary sports foods — GMP
  • 13.5 Food for special medical purposes — GMP
  • 14.1.1.2 Carbonated, mineralised and soda waters — GMP
  • 14.1.2.1 Fruit and vegetable juices — GMPFor juice separated by other than mechanical means only.
  • 14.1.2.2 Fruit and vegetable juice products — GMP
  • 14.1.3 Water based flavoured drinks — GMP
  • 14.1.4 Formulated Beverages — GMP
  • 14.1.5 Coffee, coffee substitutes, tea, herbal infusions and similar products — GMP
  • 14.2.3 Wine based drinks and reduced alcohol wines — GMP
  • 14.2.4.1 Fruit wine products and vegetable wine products — GMP
  • 14.2.5 Spirits and liqueurs — GMP
  • 14.3 Alcoholic beverages not included in item 14.2 — GMP
  • 2.1 Edible oils essentially free of water — GMP
  • 2.2.1.2 Butter products — GMP
  • 2.2.1.3 Margarine and similar products — GMP
  • 2.2.2 Oil emulsions (<80% oil) — GMP
  • 20 Foods not included in items 0 to 14 — GMP
  • 3 Ice cream and edible ices — GMP
  • 4.1.3 Fruits and vegetables that are peeled, cut, or both peeled and cut — GMP
  • 4.3 Processed fruits and vegetables — GMP
  • 5.1 Chocolate and cocoa products — GMP
  • 5.2 Sugar confectionery — GMP
  • 5.4 Icings and frostings — GMP
  • 6.3 Processed cereal and meal products — GMP
  • 6.4 Flour products (including noodles and pasta) — GMP
  • 7 Breads and bakery products — GMP
  • 8.2 Processed meat, poultry and game products in whole cuts or pieces — GMP
  • 8.3 Processed comminuted meat, poultry and game products, other than products listed in item 8.3.2 — GMP
  • 8.3.2 Sausage and sausage meat containing raw, unprocessed meat — GMP
  • 8.4 Edible casings — GMP
  • 8.5 Animal protein products — GMP
  • 9.2 Processed fish and fish products — GMP
  • 9.3 Semi preserved fish and fish products — GMP
  • 9.4 Fully preserved fish including canned fish products — GMP
Food Standards Code, Schedule 15, S15—5and 53 further provisionsretrieved 2026-10-17
CanadaHealth CanadaPermitted, with conditions

highest permitted level 4,000 mg/kg

4 permitted uses

Show every permitted use
  • In: Delysozymized egg albumen. Purpose: Restoration of functional properties. Limit: Good Manufacturing Practice. The amount of magnesium added not to exceed that lost during processing. — Health Canada, List of Permitted Food Additives with Other Purposes of Use (List 8), item M.5
  • In: Beer. Purpose: Acidity regulator. Limit: Good Manufacturing Practice. — Health Canada, List of Permitted Acidity Regulators and Acid-Reacting Materials (List 10), item M.7(a)
  • In: Bacterial cultures. Purpose: Acidity regulator. Limit: Good Manufacturing Practice. — Health Canada, List of Permitted Acidity Regulators and Acid-Reacting Materials (List 10), item M.7(b)
  • In: Starch used in the manufacture of modified starch. Purpose: Starch-modifying agent. Limit: 4,000 ppm. — Health Canada, List of Permitted Starch-Modifying Agents (List 13), item M.1
Health Canadaand 3 further provisionsretrieved 2026-10-17
European UnionEuropean Commission / EFSANo listed food uses foundThis site has not matched this substance to any food use on this jurisdiction’s list of authorised food additives. A food additive may be used only in foods that list names. Flavourings, enzymes, processing aids and added nutrients are regulated separately and do not appear on it.
Great BritainFood Standards Agency / Food Standards ScotlandNo listed food uses foundThis site has not matched this substance to any food use on this jurisdiction’s list of authorised food additives. A food additive may be used only in foods that list names. Flavourings, enzymes, processing aids and added nutrients are regulated separately and do not appear on it.
JapanConsumer Affairs AgencyPermitted, with conditions
Designated additive: Appended Table 1, item 457, 硫酸マグネシウム (“Magnesium Sulfate” in the unofficial English translation). …

Designated additive: Appended Table 1, item 457, 硫酸マグネシウム (“Magnesium Sulfate” in the unofficial English translation). Standards for use — Specifications and Standards for Foods, Food Additives, etc. (MHW Notification No. 370 of 1959), Part II (Food Additives), F (Standards for use): The Notification sets no standard for use (使用基準) for this additive, so it is not restricted there to particular foods or amounts. Compositional specifications for this additive, in the same Notification, are not imported and are not shown here; nor are the general rules in F 添加物一般, which apply to every additive.

Regulations for Enforcement of the Food Sanitation Act (MHW Ordinance No. 23 of 1948), Appended Table 1retrieved 2026-10-18
South KoreaMinistry of Food and Drug SafetyPermitted, with conditions
Designated food additive: Standards and Specifications for Food Additives, Part III, 1. …

Designated food additive: Standards and Specifications for Food Additives, Part III, 1. 일반식품첨가물 (general food additives), 황산마그네슘 (“Magnesium Sulfate”, the English the Code prints beside it); the Code marks it as also usable as a nutrient fortifier; 3. 영양강화제 (nutrient fortifiers), 황산마그네슘; nutrient: 마그네슘 (Mg); the Code marks it as also usable as a general food additive. Main use (주용도) of 황산마그네슘: 응고제. Standard for use (사용기준) of 황산마그네슘: (1) [to be used under the general standard for use in II. 2. 1), the minimum amount that achieves the technical effect, with no limit set for this additive in particular] “II. 2. 1)의 규정에 따라 사용하여야 한다.” The Korean is the standard as published. There is no official English translation of the current Code (the English version on MFDS’s website is the 2020 edition and has no legal effect); the English in square brackets is this site’s description of what each sentence does, not a translation of the foods or the levels. Compositional specifications (Part IV) are not imported, nor are the general standards in Part II, which apply to every additive.

Standards and Specifications for Food Additives (식품첨가물의 기준 및 규격), MFDS Notification, Part III (Standards for use, by item)retrieved 2026-10-18
United StatesFood and Drug AdministrationPermitted21 CFR 184.1443retrieved 2026-10-17
Codex AlimentariusCodex Alimentarius Commission / JECFAPermitted, with conditions

1 food category

no numerical limit (good manufacturing practice)

CXS 192-1995 Table Three, INS 518and 1 further provisionretrieved 2026-09-07

How much is permitted

A listing usually limits the quantity as well as the food. Only one of the forms that takes is a figure: quantum satis and good manufacturing practice permit the amount the technological effect requires and no more, which is a limit rather than the absence of one. Figures below are the range across every food category this page is listed in, and categories differ between regulators — see how much is permitted.

Australia and New Zealand—54 GMP
Canada4,000 mg/kg1 numeric limit, 3 GMP
Japan—1 no quantity stated
South Korea—1 no quantity stated
United States—1 no quantity stated
Codex Alimentarius—2 GMP

What it is made from

Mined as epsomite or produced from magnesium-bearing minerals and sulfuric acid.

  • Vegan
  • Vegetarian

Compare other additives on the dietary indexes.

CAS registry number
10034-99-8
InChIKey
WRUGWIBCXHJTDG-UHFFFAOYSA-L
PubChem
CID 24843

How JECFA defines it

The international specification for identity and purity, prepared by the Joint FAO/WHO Expert Committee on Food Additives and published by FAO. It is a different document from any above, written by a different body and revised on its own cycle; it is advisory, and a country adopts it or does not.

INS 518 Magnesium Sulfate

Magnesium sulfate occurs naturally in sea water, mineral springs and in minerals such as kieserite and epsomite. It is recovered from them or by reacting sulfuric acid and magnesium oxide. It is produced with one or seven molecules of water of hydration or in a dried form containing the equivalent of between 2 and 3 waters of hydration.

Synonyms: Epsom salt (heptahydrate); INS No.518

Assay, identification and purity criteria

Description and assay

Specification history
Prepared at the 68 th JECFA (2007), published in FAO JECFA Monographs 4 (2007), superseding the specifications prepared at the 63 rd JECFA (2004) and published the Combined Compendium of Food Additive Specifications, FAO JECFA Monographs 1 (2005). An ADI “not specified” was established at the 68 th JECFA (2007).
Chemical names
Magnesium sulfate
C.A.S. number
Monohydrate: 14168-73-1 Heptahydrate: 10034-99-8 Dried: 15244-36-7
Chemical formula
Monohydrate: MgSO4.H2O Heptahydrate: MgSO4.7H2O Dried: MgSO4.xH2O, where x is the average hydration value (between 2 and 3)
Formula weight
Monohydrate: 138.38 Heptahydrate: 246.47
Assay
Not less than 99.0 % and not more than 100.5% on the ignited basis
DESCRIPTION
Colourless crystals, granular crystalline powder or white powder. Crystals effloresce in warm, dry air.
FUNCTIONAL USES
Nutrient; flavour enhancer; firming agent; and processing aid (fermentation aid in the production of beer and malt beverages)
METHOD OF ASSAY
Accurately weigh about 0.5 g of the ignited sample, dissolve in 5 ml of hydrochloric acid TS, Dilute, dilute with water to 100 ml, and mix. Transfer 50 ml of this solution into a 250-ml conical flask; add 10 ml of Ammonia/Ammonium Chloride Buffer TS and 0.1 ml of Eriochrome Black TS. Titrate with 0.05 M disodium EDTA until the colour of red-purple solution changes to blue. Each ml of 0.05 M disodium EDTA is equivalent to 12.04 mg of MgSO4.

Identification

Solubility (Vol. 4)
Freely soluble in water, very soluble in boiling water, and sparingly soluble in ethanol.
Test for magnesium (Vol. 4)
Passes test
Test for sulfate (Vol. 4)
Passes test

Purity criteria

Loss on ignition (Vol. 4)
Monohydrate: between 13.0 and 16.0 %, Heptahydrate: between 40.0 and 52.0 %, Dried: between 22.0 and 32.0 % (105 ° , 2h, then 400 ° to constant weight)
pH (Vol. 4)
Between 5.5 and 7.5 (1 in 20 solution)
Chloride (Vol. 4)
Not more than 0.03% Test 1g of the sample as described under “Chloride Limit Test” using 0.9 ml of 0.01 N hydrochloric acid in the control
Arsenic (Vol. 4)
Not more than 3 mg/kg Determine by the atomic absorption hydride technique. Use Method I for sample preparation.
Iron (Vol. 4)
Not more than 20 mg/kg Use 1 ml of Iron Standard TS
Selenium (Vol. 4)
Not more than 30 mg/kg Determine using an AAS/ICP-AES technique appropriate to the specified level. The selection of sample size and method of sample preparation may be based on principles of methods described in Volume 4 (under “General Methods, Metallic Impurities”).
Lead (Vol. 4)
Not more than 2mg/kg Determine using an AAS/ICP-AES technique appropriate to the specified level. The selection of sample size and method of sample preparation may be based on principles of methods described in Volume 4 (under “General Methods, Metallic Impurities”).

FAO JECFA Monograph 4 (2007)

Every name it appears under

65 recorded names. A label may use any of them.

INS number

  • 518

CAS registry number

  • 10034-99-8
  • 14457-55-7
  • 7487-88-9

As it appears in regulation

  • Magnesium sulfate

Other names

  • 50% MAGNESIUM SULFATE
  • Assured Epsom Salt
  • Bitter salt
  • Bittersalz
  • Conclyte-Mg (TN)
  • CVS foaming muscle relief
  • CVS muscle relief
  • Daily Care Epsom Salt
  • Epsom salt
  • Epsom salt(heptahydrate)
  • Epsom Salts Relief
  • Epsomite
  • Epsomite (Mg(SO4).7H20)
  • Equate Muscle Cramp and Spasm Relief
  • H14MgO11S
  • Harmon Core Values Epsom Salt
  • Heptahydrate Magnesium Sulfate
  • Humco Epson Salt
  • ITCHY SKIN ERUPTIONS
  • Magnesia sulphurica
  • Magnesii sulfatis heptahydras
  • MAGNESIUM (AS SULFATE)
  • MAGNESIUM SALFATE
  • Magnesium sufate heptahydrate
  • Magnesium sulfate (1:1) heptahydrate
  • Magnesium sulfate (USP)
  • MAGNESIUM SULFATE 7HYD XTL
  • Magnesium sulfate [USAN:JAN]
  • Magnesium sulfate heptahydrate
  • Magnesium sulfate heptahydrate (MgSO4.7H2O)
  • Magnesium sulfate heptahydrate ACS grade
  • Magnesium Sulfate Hydrate
  • Magnesium sulfate hydrate (JP18)
  • Magnesium Sulfate in 5% Dextrose
  • Magnesium Sulfate In Dextrose
  • Magnesium Sulfate in Water
  • Magnesium Sulfate In Water For
  • MAGNESIUM SULFATE, UNSPECIFIED FORM
  • Magnesium sulfate--water (1/1/7)
  • magnesium sulfate--water (1/7)
  • Magnesium sulphate
  • magnesium sulphate heptahydrate
  • MAGNESIUM SULPHATE, UNSPECIFIED
  • MAGNESIUM(II), SULFATE, HEPTAHYDRATE
  • MAGNESIUMSULFATEHEPTAHYDRATE
  • MgSO4*7H2O
  • MgSO4.7H2O
  • NuValu Epsom Salt
  • PHUEL
  • Rapidol Sal Inglesa
  • RECOVERY BALM-COOL HEAT
  • RECOVERY BALM-ORIGINAL
  • RECOVERY BALM-ULTRA
  • Relief Epsom Salt
  • Sulfuric acid magnesium salt (1:1), heptahydrate
  • sulfuric acid magnesium salt heptahydrate
  • Sulfuric acid, magnesium salt, hydrate (1:1:7)
  • Theraworx Relief
  • Theraworx Relief Muscle Cramp and Spasm Relief

Systematic names

  • Magnesium sulfate

Hazard reference values

Values set by assessing bodies. A body that has not set a value is not listed here.
TypeValuePopulationAssessed byOpinion
ADInot specified—JECFA2007

Evidence and how bodies read it

Studies, and the differing conclusions regulators drew from them, are curated rather than machine-read, and none has been written for this substance yet.

Common questions

Assembled from what is above, in the words the questions are usually asked in. Each answer is the same statement the relevant section makes, with the same citations behind it.

What is INS 518?
INS 518 is Magnesium sulfate. Magnesium sulfate, better known as Epsom salt, is used in food as a firming agent, a nutrient source and to adjust water for brewing.
What is Magnesium sulfate used for in food?
It is listed as an acidity regulator and a flavour enhancer — the role Canada, the US and Codex assign it. This page shows every function each regulator records, with the citation for each.
Is Magnesium sulfate banned in Europe?
No. Magnesium sulfate does not appear on the EU's list of authorised food additives, which is not the same as being banned: the EU permits an additive only where it has authorised it, and usually the reason for an absence is that no one applied. The EU has made no finding against this substance. It does mean it may not be used as a food additive in the EU today.
Where is Magnesium sulfate permitted?
Of the seven regulators this site reads, Australia and New Zealand, Canada, Japan, South Korea, the US and the Codex standard permit it. Each permission is for named foods at named levels, not a blanket one; the table on this page gives them with citations.
Is Magnesium sulfate vegan?
Yes. Magnesium sulfate is not derived from animals, and is suitable for vegetarians. This page says what it is made from and how.

Sources for this page

  • anz retrieved 2026-10-17
  • ca retrieved 2026-10-17
  • jp retrieved 2026-10-18
  • kr retrieved 2026-10-18
  • ecfr retrieved 2026-10-17
  • gsfa retrieved 2026-09-07
  • jecfaspecs retrieved 2026-09-23

Full licence terms and publisher details on Sources. How this page is built and updated: Method.

Machine-readable: a JSON record of this additive is given on request —how to ask for access.

Follow changes to Magnesium sulfate:Atom feed — regulatory events, and any change the weekly refresh detects in its provisions.