Antacid (dosage in terms of magnesium oxide salt): OTC labeling: Oral: 1 tablet (400 mg) twice daily; maximum: 2 tablets (800 mg)/24 hours.
Dietary supplement (dosage in terms of magnesium oxide salt): OTC labeling: Oral: 1 to 2 tablets (400 to 800 mg) daily; maximum: 2 tablets (800 mg)/24 hours.
There are no dosage adjustments provided in the manufacturer's labeling; however, magnesium is renally excreted. Use with caution; accumulation in renal impairment may lead to magnesium toxicity.
There are no dosage adjustments provided in the manufacturer's labeling.
(For additional information see "Magnesium oxide: Pediatric drug information")
Note: 400 mg magnesium oxide = 241.3 mg elemental magnesium = 19.86 mEq elemental magnesium = 9.93 mmol elemental magnesium.
Hypomagnesemia: Limited data available: Infants, Children, and Adolescents: Dose expressed as elemental magnesium: Oral: 10 to 20 mg/kg/dose up to 4 times daily; usual adult dose: 300 mg 4 times daily (Anderson 2021; Gal 2007). Note: Achieving optimal magnesium levels using oral therapy may be difficult due to the propensity for magnesium to cause diarrhea: IV replacement may be more appropriate, particularly in situations of severe deficit.
There are no dosage adjustments provided in the manufacturer's labeling; however, magnesium is renally excreted. Use with caution; accumulation in renal impairment may lead to magnesium toxicity.
There are no dosage adjustments provided in the manufacturer's labeling.
Refer to adult dosing.
Excipient information presented when available (limited, particularly for generics); consult specific product labeling. [DSC] = Discontinued product
Capsule, Oral:
Uro-Mag: 140 mg [DSC]
Packet, Oral:
Magnesium Oxide 400: 240 mg (80 ea [DSC])
Tablet, Oral:
Mag-200: 200 mg [contains para-aminobenzoic acid]
MAGnesium-Oxide: 400 mg [contains soy polysaccarides]
Maox: 420 mg [contains fd&c yellow #5 (tartrazine)]
Generic: 100 mg, 400 mg, 420 mg, 420 (252 Mg) MG
Tablet, Oral [preservative free]:
Mag-Oxide: 200 mg [corn free, gluten free, no artificial color(s), no artificial flavor(s), starch free, sugar free, wheat free, yeast free]
Generic: 400 mg [DSC], 500 mg
May be product dependent
400 mg magnesium oxide = elemental magnesium 241.3 mg = magnesium 19.86 mEq = magnesium 9.93 mmol
Oral: Administer (preferably with food) at least 2 hours apart from other medications.
Oral: Administer at least 2 hours apart from other medications.
Dietary supplement; antacid: Dietary magnesium supplement; relief of acid indigestion and upset stomach
The following adverse drug reactions and incidences are derived from product labeling unless otherwise specified.
Frequency not defined: Gastrointestinal: Diarrhea (excessive oral doses)
Disease-related concerns:
• Acid indigestion/upset stomach (self-medication, OTC use): Appropriate use: For occasional use only; serious side effects may occur with prolonged use. For use only under the supervision of a physician in patients with kidney dysfunction or who are pregnant or breast-feeding. Unless directed by a physician, do not use for >2 weeks or exceed the recommended daily dose.
• Renal impairment: Use with caution in patients with renal impairment; accumulation of magnesium may lead to magnesium intoxication.
Multiple salt forms of magnesium exist; pay close attention to the salt form when ordering and administering magnesium; incorrect selection or substitution of one salt for another without proper dosage adjustment may result in serious over- or underdosing.
None known.
Note: Interacting drugs may not be individually listed below if they are part of a group interaction (eg, individual drugs within “CYP3A4 Inducers [Strong]” are NOT listed). For a complete list of drug interactions by individual drug name and detailed management recommendations, use the Lexicomp drug interactions program by clicking on the “Launch drug interactions program” link above.
Alfacalcidol: May increase the serum concentration of Magnesium Salts. Management: Consider using a non-magnesium-containing antacid or phosphate-binding product in patients also receiving alfacalcidol. If magnesium-containing products must be used with alfacalcidol, serum magnesium concentrations should be monitored closely. Risk D: Consider therapy modification
Alpha-Lipoic Acid: Magnesium Salts may decrease the absorption of Alpha-Lipoic Acid. Alpha-Lipoic Acid may decrease the absorption of Magnesium Salts. Management: Separate administration of alpha-lipoic acid from that of any magnesium-containing compounds by several hours. If alpha-lipoic acid is given 30 minutes before breakfast, then administer oral magnesium-containing products at lunch or dinner. Risk D: Consider therapy modification
Baloxavir Marboxil: Polyvalent Cation Containing Products may decrease the serum concentration of Baloxavir Marboxil. Risk X: Avoid combination
Bictegravir: Polyvalent Cation Containing Products may decrease the serum concentration of Bictegravir. Management: Administer bictegravir under fasting conditions at least 2 hours before or 6 hours after polyvalent cation containing products. Coadministration of bictegravir with or 2 hours after most polyvalent cation products is not recommended. Risk D: Consider therapy modification
Bisphosphonate Derivatives: Polyvalent Cation Containing Products may decrease the serum concentration of Bisphosphonate Derivatives. Management: Avoid administration of oral medications containing polyvalent cations within: 2 hours before or after tiludronate/clodronate/etidronate; 60 minutes after oral ibandronate; or 30 minutes after alendronate/risedronate. Risk D: Consider therapy modification
Cabotegravir: Polyvalent Cation Containing Products may decrease the serum concentration of Cabotegravir. Management: Administer polyvalent cation containing products at least 2 hours before or 4 hours after oral cabotegravir. Risk D: Consider therapy modification
Calcitriol (Systemic): May increase the serum concentration of Magnesium Salts. Management: Consider using a non-magnesium-containing antacid or phosphate-binding product in patients also receiving calcitriol. If magnesium-containing products must be used with calcitriol, serum magnesium concentrations should be monitored closely. Risk D: Consider therapy modification
Calcium Polystyrene Sulfonate: Laxatives (Magnesium Containing) may enhance the adverse/toxic effect of Calcium Polystyrene Sulfonate. More specifically, concomitant use of calcium polystyrene sulfonate with magnesium-containing laxatives may result in metabolic alkalosis or with sorbitol may result in intestinal necrosis. Management: Avoid concomitant use of calcium polystyrene sulfonate (rectal or oral) and magnesium-containing laxatives. Risk X: Avoid combination
Deferiprone: Polyvalent Cation Containing Products may decrease the serum concentration of Deferiprone. Management: Separate administration of deferiprone and oral medications or supplements that contain polyvalent cations by at least 4 hours. Risk D: Consider therapy modification
Dolutegravir: Magnesium Salts may decrease the serum concentration of Dolutegravir. Management: Administer dolutegravir at least 2 hours before or 6 hours after oral magnesium salts. Administer the dolutegravir/rilpivirine combination product at least 4 hours before or 6 hours after oral magnesium salts. Risk D: Consider therapy modification
Doxercalciferol: May enhance the hypermagnesemic effect of Magnesium Salts. Management: Consider using a non-magnesium-containing antacid or phosphate-binding product in patients also receiving doxercalciferol. If magnesium-containing products must be used with doxercalciferol, serum magnesium concentrations should be monitored closely. Risk D: Consider therapy modification
Eltrombopag: Polyvalent Cation Containing Products may decrease the serum concentration of Eltrombopag. Management: Administer eltrombopag at least 2 hours before or 4 hours after oral administration of any polyvalent cation containing product. Risk D: Consider therapy modification
Elvitegravir: Polyvalent Cation Containing Products may decrease the serum concentration of Elvitegravir. Management: Administer elvitegravir 2 hours before or 6 hours after the administration of polyvalent cation containing products. Risk D: Consider therapy modification
Gabapentin: Magnesium Salts may enhance the CNS depressant effect of Gabapentin. Specifically, high dose intravenous/epidural magnesium sulfate may enhance the CNS depressant effects of gabapentin. Magnesium Salts may decrease the serum concentration of Gabapentin. Management: Administer gabapentin at least 2 hours after use of a magnesium-containing antacid. Monitor patients closely for evidence of reduced response to gabapentin therapy. Monitor for CNS depression if high dose IV/epidural magnesium sulfate is used. Risk D: Consider therapy modification
Levothyroxine: Magnesium Salts may decrease the serum concentration of Levothyroxine. Management: Separate administration of oral levothyroxine and oral magnesium salts by at least 4 hours. Risk D: Consider therapy modification
Multivitamins/Fluoride (with ADE): Magnesium Salts may decrease the serum concentration of Multivitamins/Fluoride (with ADE). Specifically, magnesium salts may decrease fluoride absorption. Management: To avoid this potential interaction separate the administration of magnesium salts from administration of a fluoride-containing product by at least 1 hour. Risk D: Consider therapy modification
Neuromuscular-Blocking Agents: Magnesium Salts may enhance the neuromuscular-blocking effect of Neuromuscular-Blocking Agents. Risk C: Monitor therapy
PenicillAMINE: Polyvalent Cation Containing Products may decrease the serum concentration of PenicillAMINE. Management: Separate the administration of penicillamine and oral polyvalent cation containing products by at least 1 hour. Risk D: Consider therapy modification
Phosphate Supplements: Magnesium Salts may decrease the serum concentration of Phosphate Supplements. Management: Administer oral phosphate supplements as far apart from the administration of an oral magnesium salt as possible to minimize the significance of this interaction. Risk D: Consider therapy modification
Quinolones: Magnesium Salts may decrease the serum concentration of Quinolones. Management: Administer oral quinolones several hours before (4 h for moxi/pe/spar/enox-, 2 h for others) or after (8 h for moxi-, 6 h for cipro/dela-, 4 h for lome/pe/enox-, 3 h for gemi-, and 2 h for levo-, nor-, or ofloxacin or nalidixic acid) oral magnesium salts. Risk D: Consider therapy modification
Raltegravir: Magnesium Salts may decrease the serum concentration of Raltegravir. Management: Avoid the use of oral / enteral magnesium salts with raltegravir. No dose separation schedule has been established that adequately reduces the magnitude of interaction. Risk X: Avoid combination
Roxadustat: Polyvalent Cation Containing Products may decrease the serum concentration of Roxadustat. Management: Administer roxadustat at least 1 hour after the administration of oral polyvalent cation containing products. Risk D: Consider therapy modification
Sodium Polystyrene Sulfonate: Laxatives (Magnesium Containing) may enhance the adverse/toxic effect of Sodium Polystyrene Sulfonate. More specifically, concomitant use of sodium polystyrene sulfonate with magnesium-containing laxatives may result in metabolic alkalosis or with sorbitol may result in intestinal necrosis. Management: Avoid concomitant use of sodium polystyrene sulfonate (rectal or oral) and magnesium-containing laxatives. Risk X: Avoid combination
Tetracyclines: Magnesium Salts may decrease the absorption of Tetracyclines. Only applicable to oral preparations of each agent. Management: Avoid coadministration of oral magnesium salts and oral tetracyclines. If coadministration cannot be avoided, administer oral magnesium at least 2 hours before, or 4 hours after, oral tetracyclines. Monitor for decreased tetracycline therapeutic effects. Risk D: Consider therapy modification
Trientine: Polyvalent Cation Containing Products may decrease the serum concentration of Trientine. Management: Avoid concomitant use of trientine and polyvalent cations. If oral iron supplements are required, separate the administration by 2 hours. For other oral polyvalent cations, give trientine 1 hour before, or 1 to 2 hours after the polyvalent cation. Risk D: Consider therapy modification
Unithiol: May diminish the therapeutic effect of Polyvalent Cation Containing Products. Risk X: Avoid combination
Magnesium crosses the placenta; serum concentrations in the fetus are similar to those in the mother (Idama 1998; Osada 2002)
Magnesium is found in breast milk; concentrations remain constant during the first year of lactation and are not influenced by dietary intake under normal conditions. Magnesium requirements are the same in lactating and nonlactating females (IOM,1997).
Should be taken with food and at least 8 oz of water. Whole grains, legumes, and dark-green leafy vegetables are dietary sources of magnesium.
Dietary reference intake (elemental magnesium) (IOM 1997):
1 to 6 months: Adequate intake: 30 mg/day.
7 to 12 months: Adequate intake: 75 mg/day.
1 to 3 years: Recommended dietary allowance (RDA): 80 mg/day.
4 to 8 years: RDA: 130 mg/day.
9 to 13 years: RDA: 240 mg/day.
14 to 18 years: RDA:
Females: 360 mg/day.
Pregnancy: 400 mg/day.
Lactation: 360 mg/day.
Males: 410 mg/day.
19 to 30 years: RDA:
Females: 310 mg/day.
Pregnancy: 350 mg/day.
Lactation: 310 mg/day.
Males: 400 mg/day.
≥31 years: RDA:
Females: 320 mg/day.
Pregnancy: 360 mg/day.
Lactation: 320 mg/day.
Males: 420 mg/day.
Serum magnesium: 1.5-2.5 mg/dL; slightly different ranges are reported by different laboratories
Magnesium is important as a cofactor in many enzymatic reactions in the body involving protein synthesis and carbohydrate metabolism (at least 300 enzymatic reactions require magnesium). Actions on lipoprotein lipase have been found to be important in reducing serum cholesterol and on sodium/potassium ATPase in promoting polarization (eg, neuromuscular functioning).
Absorption: Oral: Up to 30%
Excretion: Urine (IOM 1997); feces (as unabsorbed drug)
Tablets (Mag-200 Oral)
200 mg (per each): $0.07
Tablets (Mag-Oxide Oral)
200 mg (per each): $0.03
Tablets (Magnesium Oxide Oral)
400 mg (per each): $0.03 - $0.33
400 (240 Mg) mg (per each): $0.03 - $0.08
420 mg (per each): $0.04
420 (252 Mg) mg (per each): $0.06
500 mg (per each): $0.03
Tablets (MAGnesium-Oxide Oral)
400 (240 Mg) mg (per each): $0.15
Tablets (Maox Oral)
420 mg (per each): $0.04
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