Magnesium citrate

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Magnesium citrate
Magnesium citrate.png
IUPAC name
Magnesium 2-hydroxypropane-1,2,3-tricarboxylate
7779-25-1 N
ATC code A06AD19
A12CC04, B05CB03
ChemSpider 8605 N
EC number 231-923-9
Jmol-3D images Image
PubChem 24511
Molar mass 214.41 g·mol−1
20 g/100ml
Related compounds
Related salts
Magnesium citrate (3:2)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Magnesium citrate (1:1) (1 magnesium atom per citrate molecule), called below by the common but ambiguous name magnesium citrate (which can also mean magnesium citrate (3:2)), is a magnesium preparation in salt form with citric acid. It is a chemical agent used medicinally as a saline laxative and to completely empty the bowel prior to a major surgery or colonoscopy. It is available without a prescription, both as a generic and under the brand names Citromag and Citroma. It is also used in the pill form as a magnesium dietary supplement. It contains 11.3% magnesium by weight. Compared to magnesium citrate (3:2), it is much more water-soluble, less alkaline, and contains 29.9% less magnesium by weight.

As a food additive, magnesium citrate is used to regulate acidity and is known as E number E345.

Mechanism of action[edit]

Magnesium citrate works by attracting water through the tissues by a process known as osmosis. Once in the intestine, it can attract enough water into the intestine to induce defecation. The additional water stimulates bowel motility. This means it can also be used to treat rectal and colon problems. Magnesium citrate functions best on an empty stomach, and should always be followed with a full (eight ounce or 25 cl) glass of water or juice to help the magnesium citrate absorb properly and help prevent any complications. Magnesium citrate is generally not a harmful substance, but care should be taken by consulting a healthcare professional if any adverse health problems are suspected or experienced.

Use and dosage[edit]

The maximum upper tolerance limit (UTL) for magnesium in supplement form for adults is 350 mg per day of elemental magnesium according to the National Institutes of Health (NIH).[1] In addition, according to the NIH, total dietary requirements for magnesium from all sources (i.e., food and supplements) is 320–420 mg of elemental magnesium per day, though there is no UT for dietary magnesium.

As a laxative syrup with a concentration of 1.745 g of magnesium citrate per fluid ounce, a typical dose for adults and children twelve years or older is between 7 and 10 US fluid ounces (210 and 300 ml; 7.3 and 10.4 imp fl oz), followed immediately with a full 8 US fluid ounces (240 ml; 8.3 imp fl oz) glass of water. Consuming an adult dose of 10 oz of laxative syrup (@ 1.745 g/oz) implies a consumption of 17.45 g of magnesium citrate in a single 10 oz dose resulting in a consumption of approximately 2.0 g of elemental magnesium per single dose. Given that this laxative dose contains five times the recommended nutritional dose for magnesium, caution should be taken to avoid prolonged usage (i.e., over five days) and to follow the manufacturer's instructions strictly.[citation needed] For children between three and twelve years of age, the typical dose is roughly half that,[citation needed] based on physician recommendation. Magnesium citrate is not recommended for use in children and infants two years of age or less.[2]

Although less common, as a magnesium supplement the citrate form is sometimes used because it is believed to be more bio-available than other common pill forms, such as magnesium oxide.[citation needed] However, according to one study, magnesium gluconate is marginally more bio-available than magnesium citrate.[3]

Magnesium citrate, as a supplement in pill form, is useful for the prevention of kidney stones.[4]

Side effects[edit]

It is always important to correctly follow the prescribed doses; extreme magnesium overdose can result in serious complication such as slow heart beat, low blood pressure, nausea, drowsiness, etc. If severe enough, an overdose can even result in coma or death.[5] However, a moderate overdose will be excreted through the kidneys, unless one suffers from serious kidney problems.

Magnesium citrate solutions generally produce bowel movement in one half to six hours. Rectal bleeding or failure to have a bowel movement after use could be signs of a serious condition.

See also[edit]

  • Magnesium citrate (3:2) A much less water-soluble, more alkaline version of this salt, which contains 42.6% more magnesium by weight. It is also available through pill or tablet form.
  • ATC code A12


  1. ^ Magnesium. Office of Dietary Supplements (ODS). National Institutes of Health (NIH).
  2. ^ "magnesium_citrate-oral" at
  3. ^ Coudray, C; Rambeau, M; Feillet-Coudray, C; Gueux, E; Tressol, JC; Mazur, A; Rayssiguier, Y (December 2005). "Study of magnesium bioavailability from ten organic and inorganic Mg salts in Mg-depleted rats using a stable isotope approach". Magnes Res 18 (4): 215–23. PMID 16548135. 
  4. ^ Ettinger, B; Pak, CY; Citron, JT; Thomas, C; Adams-Huet, B; Vangessel, A (December 1997). "Potassium-magnesium citrate is an effective prophylaxis against recurrent calcium oxalate nephrolithiasis". J Urol 158 (6): 2069–73. doi:10.1016/S0022-5347(01)68155-2. PMID 9366314. 
  5. ^ magnesium citrate. Cerner Multum. 12 April 2009.

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