Magnesium sulfate (medical use)

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Magnesium sulfate
Magnesium sulfate heptahydrate
Trade namesEpsom salt, others
Clinical data
Main usesEclampsia, low blood magnesium[1][2]
Side effectsLow blood pressure, skin flushing, low blood calcium[2]
  • US: D (Evidence of risk)[3][2]
Routes of
IV, IM, by mouth, topical
Defined daily dose3 to 7 grams by mouth, and 1 gram by injection.[4][5]
External links
Chemical and physical data
FormulaMgSO4 - 7H2O
Molar mass120.366
3D model (JSmol)
  • [O-]S(=O)(=O)[O-].[Mg+2]
  • InChI=1S/Mg.H2O4S/c;1-5(2,3)4/h;(H2,1,2,3,4)/q+2;/p-2

Magnesium sulfate as a medication is used to treat and prevent low blood magnesium and seizures in women with eclampsia.[2] It is also used in the treatment of torsades de pointes, severe asthma exacerbations, constipation, and barium poisoning.[2][6] It is given by injection into a vein or muscle as well as by mouth.[2][6] As epsom salts, it is also used for mineral baths.[7]

Common side effects include low blood pressure, skin flushing, and low blood calcium.[2] Other side effects may include vomiting, muscle weakness, and decreased breathing.[8] While there is evidence that use during pregnancy may harm the baby, the benefits in certain conditions are greater than the risks.[9] Its use during breastfeeding is deemed to be safe.[9] Magnesium sulfate for medical use is the magnesium sulfate heptahydrate salt.[6] The way it works is not fully understood, but is believed to involve depressing the action of neurons.[2]

Magnesium sulfate came into medical use at least as early as 1618.[10] It is on the World Health Organization's List of Essential Medicines.[11] The wholesale cost in the developing world is about US$0.35–8.73 per 10 ml of 50% solution.[12] In the United Kingdom 4 ml of 20% solution costs the NHS about 10.23 pounds.[6] In the United States a course of medication typically costs less than $25.[3]

Medical use

Magnesium sulfate intravenous solution

Magnesium sulfate can be given by mouth, respiratory, or intravenous routes.

Magnesium deficiency

Magnesium sulfate is used as a replacement therapy for magnesium deficiency[13]


Magnesium sulfate may be used as an antiarrhythmic agent for torsades de pointes in cardiac arrest under the ECC guidelines and for managing quinidine-induced arrhythmias.[14]


Magnesium sulfate may be used as bronchodilator after beta-agonist and anticholinergic agents have been tried, e.g. in severe exacerbations of asthma,[15] The salt can be administered by nebulization[15] or by intravenous injection.


Magnesium sulfate is effective in decreasing the risk that pre-eclampsia progresses to eclampsia.[16] Intravenous magnesium sulfate is used to prevent and treat seizures of eclampsia. It reduces the systolic blood pressure but does not alter the diastolic blood pressure, so the blood perfusion to the fetus is not compromised. It is also commonly used for eclampsia where compared to diazepam or phenytoin it results in better outcomes.[17][18]

Early delivery

Magnesium sulfate was once used as a tocolytic,[19][20] but meta-analyses have failed to support it as an anti-contraction medication.[21][22] Usage for prolonged periods (more than five to seven days) may result in health problems for the baby.[23]

In those at risk of an early delivery, magnesium sulfate appears to decrease the risk of cerebral palsy.[24][25] It is unclear if it helps those who are born at term.[26] Guidelines for the use of magnesium sulfate in mothers at risk of preterm labour are not strongly adhered to.[27]

Lead poisoning

Magnesium sulfate was historically used as a treatment for lead poisoning. Prior to the development of chelation therapy, cases of accidental lead ingestion were often immediately treated with magnesium sulfate, which would cause the lead to be precipitated out and, with a high enough dose, literally purged from the digestive system.[28][29] In this application, magnesium sulfate saw particular use in veterinary medicine of the early-to-mid 20th century; Epsom salt was already available on many farms for agricultural purposes, and it was often prescribed in the treatment of farm animals which inadvertently ingested lead.[30][31]

Bath salts

Epsom salt baths have been claimed to also soothe and hasten recovery of muscle pain, soreness, or injury. However, these claims have not been scientifically confirmed.[32] The solubility of magnesium sulfate water is inhibited by lipids in lotions resulting in variable absorption rates when applied to the skin. Temperature and concentration are also factors.[33]

Drawing paste

In the UK, a medication containing magnesium sulfate, called "drawing paste", is claimed to be useful for small boils or localised infections.[34] The standard British Pharmacopoeia composition is dried magnesium sulfate 47.76% (by mass), phenol 0.49%, and glycerol to balance.[34]


The defined daily dose is 3 to 7 grams by mouth, and 1 gram by injection.[4][5] For preeclampsia or eclampsia it is generally given as a 4 gram dose over 15 minutes followed by 1 gram per hour.[1] If seizures occur again 2 to 4 more grams may be given.[1]

A 1 gram dose of magnesium sulfate is the same as 4 mmol or 8 mEq of magnesium.[1]

Side effects

An abnormally elevated plasma concentration of magnesium is called hypermagnesemia.


Magnesium sulfate has been used as an experimental treatment of Irukandji syndrome caused by envenomation by certain species of Irukandji jellyfish, but the efficacy of this treatment remains unproven.[35]

See also


  1. 1.0 1.1 1.2 1.3 "MAGNESIUM SULFATE = MgSO4 injectable - Essential drugs". Archived from the original on 28 August 2021. Retrieved 2 September 2020.
  2. 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 "Magnesium Sulfate". The American Society of Health-System Pharmacists. Archived from the original on 21 May 2016. Retrieved 8 January 2017.
  3. 3.0 3.1 Hamilton, Richart (2015). Tarascon Pocket Pharmacopoeia 2015 Deluxe Lab-Coat Edition. Jones & Bartlett Learning. p. 220. ISBN 9781284057560.
  4. 4.0 4.1 "WHOCC - ATC/DDD Index". Archived from the original on 30 September 2020. Retrieved 2 September 2020.
  5. 5.0 5.1 "WHOCC - ATC/DDD Index". Archived from the original on 20 September 2020. Retrieved 2 September 2020.
  6. 6.0 6.1 6.2 6.3 British national formulary : BNF 69 (69 ed.). British Medical Association. 2015. p. 696. ISBN 9780857111562.
  7. Kogel, Jessica Elzea (2006). Industrial Minerals & Rocks: Commodities, Markets, and Uses. SME. p. 625. ISBN 9780873352338. Archived from the original on 2017-09-18.
  8. World Health Organization (2009). Stuart MC, Kouimtzi M, Hill SR (eds.). WHO Model Formulary 2008. World Health Organization. p. 75. hdl:10665/44053. ISBN 9789241547659.
  9. 9.0 9.1 "Magnesium sulfate Use During Pregnancy |". Archived from the original on 2017-07-02.
  10. Willett, Edward (2006). Magnesium. The Rosen Publishing Group. p. 5. ISBN 9781404210073. Archived from the original on 2017-09-18.
  11. World Health Organization (2019). World Health Organization model list of essential medicines: 21st list 2019. Geneva: World Health Organization. hdl:10665/325771. WHO/MVP/EMP/IAU/2019.06. License: CC BY-NC-SA 3.0 IGO.
  12. "Magnesium Sulfate". International Drug Price Indicator Guide. Archived from the original on 21 November 2018. Retrieved 8 December 2016.
  13. "Pharmaceutical Information – Magnesium Sulfate". RxMed. Archived from the original on 3 April 2009. Retrieved 2009-07-06.
  14. "CPR and First Aid: Antiarrhythmic Drugs During and Immediately After Cardiac Arrest (section)". American Heart Association. Archived from the original on 28 August 2021. Retrieved 29 August 2016. Previous ACLS guidelines addressed the use of magnesium in cardiac arrest with polymorphic ventricular tachycardia (ie, torsades de pointes) or suspected hypomagnesemia, and this has not been reevaluated in the 2015 Guidelines Update. These previous guidelines recommended defibrillation for termination of polymorphic VT (ie, torsades de pointes), followed by consideration of intravenous magnesium sulfate when secondary to a long QT interval.
  15. 15.0 15.1 Blitz M, Blitz S, Hughes R, Diner B, Beasley R, Knopp J, Rowe BH (2005). "Aerosolized magnesium sulfate for acute asthma: a systematic review". Chest. 128 (1): 337–344. doi:10.1378/chest.128.1.337. PMID 16002955..
  16. Duley, L; Gülmezoglu, AM; Henderson-Smart, DJ; Chou, D (Nov 10, 2010). "Magnesium sulphate and other anticonvulsants for women with pre-eclampsia". The Cochrane Database of Systematic Reviews (11): CD000025. doi:10.1002/14651858.CD000025.pub2. PMC 7061250. PMID 21069663.
  17. Duley, L; Henderson-Smart, DJ; Walker, GJ; Chou, D (Dec 8, 2010). "Magnesium sulphate versus diazepam for eclampsia". The Cochrane Database of Systematic Reviews (12): CD000127. doi:10.1002/14651858.CD000127.pub2. PMC 7045443. PMID 21154341.
  18. Duley, L; Henderson-Smart, DJ; Chou, D (Oct 6, 2010). "Magnesium sulphate versus phenytoin for eclampsia". The Cochrane Database of Systematic Reviews (10): CD000128. doi:10.1002/14651858.CD000128.pub2. PMID 20927719.
  19. "Magnesium sulfate for preterm labor". 2007-01-19. Archived from the original on 2009-06-24. Retrieved 2009-07-06.
  20. Lewis DF (September 2005). "Magnesium sulfate: the first-line tocolytic". Obstetrics and Gynecology Clinics of North America. 32 (3): 485–500. doi:10.1016/j.ogc.2005.03.002. PMID 16125045. Archived from the original on 2019-12-13. Retrieved 2017-01-16.
  21. Simhan HN, Caritis SN (2007). "Prevention of Preterm Delivery". New England Journal of Medicine. 357 (5): 477–487. doi:10.1056/NEJMra050435. PMID 17671256.
  22. Nanda, K; Grimes, DA (2006). "Magnesium sulfate tocolysis: Time to quit". Obstetrics and Gynecology. 108 (4): 986–989. doi:10.1097/01.AOG.0000236445.18265.93. PMID 17012463. S2CID 30014199.
  23. "Magnesium Sulfate: Drug Safety Communication – Recommendation Against Prolonged Use in Pre-term Labor". FDA. Archived from the original on 3 June 2013. Retrieved 2 June 2013.
  24. Doyle, LW; Crowther, CA; Middleton, P; Marret, S; Rouse, D (January 21, 2009). "Magnesium sulphate for women at risk of preterm birth for neuroprotection of the fetus". The Cochrane Database of Systematic Reviews (1): CD004661. doi:10.1002/14651858.CD004661.pub3. PMID 19160238.
  25. Wolf, HT; Hegaard, HK; Greisen, G; Huusom, L; Hedegaard, M (February 2012). "Treatment with magnesium sulphate in pre-term birth: a systematic review and meta-analysis of observational studies". Journal of Obstetrics and Gynaecology. 32 (2): 135–140. doi:10.3109/01443615.2011.638999. PMID 22296422. S2CID 24012925.
  26. Nguyen, TM; Crowther, CA; Wilkinson, D; Bain, E (February 28, 2013). "Magnesium sulphate for women at term for neuroprotection of the fetus". The Cochrane Database of Systematic Reviews. 2 (2): CD009395. doi:10.1002/14651858.cd009395.pub2. PMID 23450601.
  27. Shih, Sophy T F; Tonmukayakul, Utsana; Imms, Christine; Reddihough, Dinah; Graham, H Kerr; Cox, Liz; Carter, Rob (10 January 2018). "Economic evaluation and cost of interventions for cerebral palsy: a systematic review". Developmental Medicine & Child Neurology. 60 (6): 543–558. doi:10.1111/dmcn.13653. PMID 29319155.
  28. Wood, H. C. (1877). A Treatise on Therapeutics, Comprising Materia Medica and Toxicology, with Especial Reference to the Application of the Physiological Action of Drugs to Clinical Medicine. Philadelphia: J. B. Lippincott & Co. p. 34. Archived from the original on 2021-04-27. Retrieved 2020-08-03. The treatment of acute lead-poisoning consists in the evacuation of the stomach, if necessary, the exhibition of the sulphate of sodium or of magnesium, and the meeting of the indications as they arrive. The Epsom and Glauber's salts act as chemical antidotes, by precipitating the insoluble sulphate of lead, and also, if in excess, empty the bowel of the compound formed.
  29. Rangan, Cyrus (January 27, 2016). Lead and Mercury (PDF). Children's Environmental Health Symposium San Diego 2016: Protecting Children's Environmental Health in the U.S.-Mexico Border Region. San Diego, CA: Environmental Protection Agency. Archived (PDF) from the original on June 8, 2017. Retrieved August 2, 2020.
  30. Barker, C. A. V. (January 1945). "Experience with Lead Poisoning". Canadian Journal of Comparative Medicine and Veterinary Science. 9 (1): 6–8. PMC 1660962. PMID 17648099. Udall (1) suggests sodium citrate as of some value together with Epsom salts which will bring about a precipitation of the lead in the form of an insoluble compound. Nelson (3) reported a case that survived following the use of a 20% magnesium sulphate solution intravenously, subcutaneously and orally. McIntosh (5) has suggested that purgative doses of Epsom salts may be effective in combining with the lead and overcoming the toxicity.
  31. Herriot, James (1972). All Creatures Great and Small. New York: St. Martin's Press. p. 157. ISBN 0-312-08498-6. Archived from the original on 2021-04-27. Retrieved 2020-08-03. The specific antidotes to metal poisoning had not been discovered and the only thing which sometimes did a bit of good was magnesium sulphate which caused the precipitation of insoluble lead sulphate. The homely term for magnesium sulphate is, of course, epsom salts.
  32. Ingraham, Paul. "Does Epsom Salt Work? The science of Epsom salt bathing for recovery from muscle pain, soreness, or injury". Pain Science. Archived from the original on 10 September 2016. Retrieved 29 August 2016.
  33. "Does Epsom Salt Work?". Archived from the original on 2016-09-10. Retrieved 2018-05-05.
  34. 34.0 34.1 "Boots Magnesium Sulfate Paste B.P. - Patient Information Leaflet (PIL) - (eMC)". Archived from the original on 12 April 2018. Retrieved 14 April 2018.
  35. Corkeron M (2003). "Magnesium infusion to treat Irukandji syndrome". Medical Journal of Australia. 178 (8): 411. doi:10.5694/j.1326-5377.2003.tb05263.x. PMID 12697017.

External links

  • "Magnesium sulfate". Drug Information Portal. U.S. National Library of Medicine. Archived from the original on 2020-07-06. Retrieved 2020-07-06.