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Magnesium Chloride Dosage

Applies to the following strength(s): 64 mg ; 200 mg/mL

The information at is not a substitute for medical advice. ALWAYS consult your doctor or pharmacist.

Usual Adult Dose for Hypomagnesemia

Mild hypomagnesemia:
If oral administration is tolerated, mild hypomagnesemia may be treated with Slow-Mag 1 tablet (535 mg magnesium chloride, 64 mg elemental magnesium) orally once a day.

Severe hypomagnesemia:
40 mEq (4 g magnesium chloride) in 5% dextrose or normal saline by IV infusion once over 3 hours.

Usual Adult Dose for Myocardial Infarction

10 mEq in 5% dextrose or normal saline by IV infusion once within the first 24 hours of infarction.

Usual Pediatric Dose for Hypomagnesemia

Hypomagnesemia: IV: Magnesium chloride: 0.2 to 0.4 mEq/kg/dose every 8 to 12 hours for 2 to 3 doses
Daily maintenance magnesium: IV: Magnesium chloride: 0.25 to 0.5 mEq/kg/day

IM or IV: Magnesium chloride: 0.2 to 0.4 mEq/kg/dose every 4 to 6 hours for 3 to 4 doses; maximum single dose: 16 mEq
Oral: 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: Magnesium chloride: 10 to 20 mg/kg elemental magnesium per dose up to 4 times/day

Daily maintenance magnesium: IV Magnesium chloride:
Infants and Children less than or equal to 45 kg: 0.25 to 0.5 mEq/kg/day
Adolescents greater than 45 kg and Adults: 0.2 to 0.5 mEq/kg/day or 3 to 10 mEq/1000 kcal/day (maximum: 8 to 20 mEq/day).

Renal Dose Adjustments

Magnesium salts should be used cautiously in patients with renal impairment due to increased risk of hypermagnesemia.

Liver Dose Adjustments

Data not available

Dose Adjustments

The dose may be increased periodically to achieve a normal serum magnesium level.


Because magnesium is primarily eliminated by the kidney, there is significant risk of hypermagnesemia in patients with renal impairment.


Data not available; however, use of magnesium salts is generally contraindicated in renal failure.

Other Comments

Magnesium supplements are often used with "low normal" serum magnesium levels in patients predisposed to hypomagnesemia (e.g., patients on diuretics).