Magnesium stearate

Magnesium stearate is the chemical compound with the formula Mg(C
. It is a soap, consisting of salt containing two equivalents of stearate (the anion of stearic acid) and one magnesium cation (Mg2+). Magnesium stearate is a white, water-insoluble powder. Its applications exploit its softness, insolubility in many solvents, and low toxicity. It is used as a release agent and as a component or lubricant in the production of pharmaceuticals and cosmetics.[1]

Magnesium stearate
IUPAC name
Magnesium octadecanoate
3D model (JSmol)
ECHA InfoCard 100.008.320
E number E572 (acidity regulators, ...)
  • InChI=1S/2C18H36O2.Mg/c2*1-2-3-4-5-6-7-8-9-10-11-12-13-14-15-16-17-18(19)20;/h2*2-17H2,1H3,(H,19,20);/q;;+2/p-2 Y
  • InChI=1/2C18H36O2.Mg/c2*1-2-3-4-5-6-7-8-9-10-11-12-13-14-15-16-17-18(19)20;/h2*2-17H2,1H3,(H,19,20);/q;;+2/p-2
Molar mass 591.27 g/mol
Appearance light white powder
Odor slight
Density 1.026 g/cm3
Melting point 88.5 °C (191.3 °F; 361.6 K)
0.003 g/100 mL (15 °C)
0.004 g/100 mL (25 °C)
0.008 g/100 mL (50 °C)
Solubility negligible in ether and alcohol
slightly soluble in benzene
NFPA 704 (fire diamond)
Flash point 250 °C (482 °F; 523 K)
Lethal dose or concentration (LD, LC):
> 1000 mg/kg (oral, rat)
Safety data sheet (SDS) External MSDS
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Y verify (what is YN ?)
Infobox references


Magnesium stearate is produced by the reaction of sodium stearate with magnesium salts or by treating magnesium oxide with stearic acid.[1][2]


Magnesium stearate is often used as an anti-adherent[3] in the manufacture of medical tablets, capsules and powders.[4] In this regard, the substance is also useful because it has lubricating properties, preventing ingredients from sticking to manufacturing equipment during the compression of chemical powders into solid tablets; magnesium stearate is the most commonly used lubricant for tablets.[5] However, it might cause lower wettability and slower disintegration of the tablets and slower and even lower dissolution of the drug.[6]

Magnesium stearate can also be used efficiently in dry coating processes.[7][8][9]

In the production of pressed candies, magnesium stearate serves as a release agent. It is also used to bind sugar in hard candies such as mints.[10]

Magnesium stearate is a common ingredient in baby formulas.[11]

In the EU and EFTA it is listed as food additive E470b.


Magnesium stearate is a major component of bathtub rings. When produced by soap and hard water, magnesium stearate and calcium stearate both form a white solid insoluble in water, and are collectively known as soap scum.


Magnesium stearate is generally considered safe for human consumption at levels below 2500 mg per kg of body weight per day[12] and is classified in the United States as generally recognized as safe (GRAS). In 1979, the FDA's Subcommittee on GRAS Substances (SCOGS) reported, "There is no evidence in the available information on ... magnesium stearate ... that demonstrates, or suggests reasonable grounds to suspect, a hazard to the public when they are used at levels that are now current and in the manner now practiced, or which might reasonably be expected in the future."[13]


  1. Angelo Nora, Alfred Szczepanek, Gunther Koenen, "Metallic Soaps" in Ullmann's Encyclopedia of Industrial Chemistry 2005 Wiley-VCH, Weinheim. doi:10.1002/14356007.a16_361
  2. A. G. Dobson and H. H. Hatt (1953). "Stearone". Organic Syntheses. 33: 84. doi:10.15227/orgsyn.033.0084.
  3. Ritter, Steve (2008). "What's That Stuff? Excipients: Inactive ingredients in medicines serve multiple functions in drug delivery". Chemical & Engineering News. 86 (1): 25. doi:10.1021/cen-v086n001.p025.
  4. Sworbrick, James; Boylan, James C. (1990). Encyclopedia of pharmaceutical technology. p. 2274. ISBN 9780824728243.
  5. Weiner, Myra L.; Kotkoskie, Lois A. (1999). Excipient Toxicity and Safety. p. 10. ISBN 9780824782108.
  6. Demuth; et al. (2017). "Investigation of Deteriorated Dissolution of Amorphous Itraconazole: Description of Incompatibility with Magnesium Stearate and Possible Solutions". Molecular Pharmaceutics. 14 (11): 3927–3934. doi:10.1021/acs.molpharmaceut.7b00629. PMID 28972782.
  7. Ouabbas Y, Dodds J., Galet L., Chamayou A. , Baron M. (2009). "Particle-particle coating in a cyclomix impact mixer" (PDF). Powder Technol. 189 (2): 245–252. doi:10.1016/j.powtec.2008.04.031.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  8. Thomas G., Ouabbas Y., Grosseau P., Baron M., Chamayou A., Galet L. (2009). "Modeling the main interaction forces between powder particles. Application to silica gel-magnesium stearate mixtures". Applied Surface Science. 255 (17): 7500–7507. Bibcode:2009ApSS..255.7500T. CiteSeerX doi:10.1016/j.apsusc.2009.03.099.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  9. Sato A., Serris E., Grosseau P., Thomas G., Galet L., Chamayou A. , Baron M. (2013). "Experiment and simulation of dry particle coating" (PDF). Chem. Eng. Science. 86: 164–172. doi:10.1016/j.ces.2012.07.037.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  11. Erich Lück and Gert-Wolfhard von Rymon Lipinski (2002). "Foods, 3. Food Additives". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a11_561. ISBN 978-3527306732.
  12. Søndergaarda, D.; Meyera, O.; Würtzena, G. (1980). "Magnesium stearate given peroprally to rats. A short term study". Toxicology. 17 (1): 51–55. doi:10.1016/0300-483X(80)90026-8. PMID 7434368.
  13. FDA's SCOGS Database; Report No. 60; ID Code: 557-04-0; Year: 1979
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