Magnesium (medical use)

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INN: Magnesium ion
CAS Number
  • 7439-95-4
PubChem CID
Chemical and physical data
Molar mass24.305 g·mol−1

Magnesium salts are available as a medication in a number of formulations. They are used to treat magnesium deficiency, low blood magnesium, eclampsia, and several other conditions. Magnesium is important to health.

Usually in lower dosages, magnesium is commonly included in dietary mineral preparations, including many multivitamin preparations. Chelated magnesium is sometimes used to aid in absorption.

In 2018, it was the 199th most commonly prescribed medication in the United States, with more than 2 million prescriptions.[1][2]

Medical uses[edit]

  • As a bronchodilator after beta-agonist and anticholinergic agents have been tried, e.g. in severe exacerbations of asthma.[3] Recent studies have revealed that magnesium sulfate can be nebulized to reduce the symptoms of acute asthma.[3] It is commonly administered via the intravenous route for the management of severe asthma attacks.
  • Obstetrics: Magnesium sulfate is used to prevent seizures in women with preeclampsia and eclampsia, and is also used for fetal neuroprotection in preterm deliveries, but has been shown to be an ineffective tocolytic agent.[4][5]

Side effects[edit]

More common side effects from magnesium include upset stomach and diarrhea, and calcium deficiency if calcium levels are already low.[6]


Overdose of magnesium (hypermagnesemia) is only possible in special circumstances. It can cause diarrhea,[7] nausea, vomiting, severely lowered blood pressure, confusion, slowed heart rate, respiratory paralysis.[6] In very severe cases, it can cause coma, cardiac arrhythmia, cardiac arrest and death.[6]

Magnesium overdose can be counteracted by administering calcium gluconate.[8]

Types of preparations[edit]

In practice, magnesium is given in a salt form together with any of several anionic compounds serving as counter-ions, such as chloride or sulfate. Nevertheless, magnesium is generally presumed to be the active component. An exception is the administration of magnesium sulfate in barium chloride poisoning,[9] where sulfate binds to barium to form insoluble barium sulfate.

Magnesium is absorbed orally at about 30% bioavailability from any water soluble salt, such as magnesium chloride or magnesium citrate. The citrate is the least expensive soluble (high bioavailability) oral magnesium salt available in supplements, with 100 mg and 200 mg magnesium typically contained per capsule or tablet.

Magnesium aspartate, chloride, lactate, citrate and glycinate each have bioavailability 4 times greater than the oxide form and are equivalent to each other per amount of magnesium, though not in price.[10][11]

The ligand of choice for large-scale manufacturers of multivitamins and minerals containing magnesium is the magnesium oxide due to its compactness, high magnesium content by weight, low cost, and ease-of-use in manufacturing. However it is insoluble in water. Insoluble magnesium salts such as magnesium oxide or magnesium hydroxide (milk of magnesia) depend on stomach acid for neutralization before they can be absorbed, and thus are relatively poor oral magnesium sources, on average.

Magnesium sulfate (Epsom salts) is soluble in water. It is commonly used as a laxative, owing to the poor absorption of the sulfate component. In lower doses, they may be used as an oral magnesium source, however.

Intravenous or intramuscular magnesium is generally in the form of magnesium sulfate solution. Intravenous or intramuscular magnesium is completely bioavailable, and effective. It is used in severe hypomagnesemia and eclampsia.

See also[edit]


  1. ^ "The Top 300 of 2021". ClinCalc. Retrieved 18 February 2021.
  2. ^ "Magnesium - Drug Usage Statistics". ClinCalc. Retrieved 18 February 2021.
  3. ^ a b 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): 337–44. doi:10.1378/chest.128.1.337. PMID 16002955.
  4. ^ "Committee Opinion No 652: Magnesium Sulfate Use in Obstetrics". Obstetrics and Gynecology. 127 (1): e52–53. January 2016. doi:10.1097/AOG.0000000000001267. ISSN 1873-233X. PMID 26695587.
  5. ^ Crowther, Caroline A.; Brown, Julie; McKinlay, Christopher J. D.; Middleton, Philippa (15 August 2014). "Magnesium sulphate for preventing preterm birth in threatened preterm labour". The Cochrane Database of Systematic Reviews (8): CD001060. doi:10.1002/14651858.CD001060.pub2. ISSN 1469-493X. PMID 25126773.
  6. ^ a b c Magnesium at University of Maryland Medical Center (UMMC). Reviewed last on: 17 June 2011 by Steven D. Ehrlich
  7. ^ Section: Health Risks from Excessive Magnesium
  8. ^ Omu AE, Al-Harmi J, Vedi HL, Mlechkova L, Sayed AF, Al-Ragum NS (2008). "Magnesium sulphate therapy in women with pre-eclampsia and eclampsia in Kuwait". Med Princ Pract. 17 (3): 227–32. doi:10.1159/000117797. PMID 18408392.
  9. ^ "BARIUM CHLORIDE DIHYDRATE 4. First Aid Measures". Retrieved 6 July 2009.
  10. ^ Firoz M, Graber M: "Bioavailability of US commercial magnesium preparations.", Magnesium Research 2001 Dec;14(4):257-62.
  11. ^ Lindberg JS, Zobitz MM, Poindexter JR, Pak CY: "Magnesium bioavailability from magnesium citrate and magnesium oxide.", J Am Coll Nutr. 1990 Feb;9(1):48-55.