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Magnesium Sulfate Dosage

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

Usual Adult Dose for:

Additional dosage information:

Usual Adult Dose for Hypomagnesemia

1 g IM every 6 hours for 4 doses (mild hypomagnesemia) or
as much as 2 mEq/kg (0.5 mL of a 50% solution) within 4 hours if necessary (more severe hypomagnesemia) or
5 g in 1 L IV fluid over 3 hours.

Administration should be discontinued as soon as the desired clinical effect is achieved and the serum level is normal.

Usual Adult Dose for Ventricular Arrhythmia

Initial dose: 1 to 3 g IV bolus over 2 to 15 minutes.
Most studies have continued infusions for 24 to 48 hours.
A 1 to 3 g bolus may be repeated in 15 minutes.
Thereafter, 1 to 2 g may be administered by continuous IV infusion.

Usual Adult Dose for Seizure Prophylaxis

Seizure Prevention in Preeclampsia/Eclampsia:
Initial: IM: 4 to 5 g of a 50% solution every 4 hours as necessary.
IV: 4 g of a 10% to 20% solution, not exceeding 1.5 mL/min of a 10% solution.
Maintenance: IV Infusion: 1 to 2 g/hour. Maximum dose should not exceed 30 to 40 g/day.
Duration: Continuous administration beyond 5 to 7 days can cause fetal harm.

Renal Dose Adjustments

Patients in severe renal failure should not receive magnesium due to the potential for toxicity from accumulation.

Liver Dose Adjustments

Data not available


Use with caution or not at all in patients with a creatinine clearance of less than 25 mL/min. Patients with a creatinine clearance of less than 25 mL/min who do receive magnesium should have magnesium levels monitored.


Data not available

Other Comments

When possible, oral magnesium should be used for mild to moderate chronic hypomagnesemia (renal wasting).