Management of Magnesium Overdose

Initial Assessment

Evaluate vital signs including blood pressure, heart rate, respiratory rate, and oxygen saturation, as recommended by the American Heart Association, to assess the severity of magnesium overdose 1, 2
Obtain 12-lead ECG to assess for cardiac conduction abnormalities, such as prolonged PR, QRS, QT intervals, as suggested by the American College of Cardiology 2, 3
Check deep tendon reflexes and neurological status to identify potential neurological effects of magnesium toxicity, as recommended by the American Academy of Neurology 4, 5
Obtain serum magnesium, potassium, calcium, and creatinine levels to assess electrolyte balance and renal function, as recommended by the National Kidney Foundation 2, 5

Mild-moderate toxicity (2.5-5 mmol/L) presents with nausea, flushing, headache, lethargy, diminished deep tendon reflexes, and ECG changes, such as prolonged PR, QRS, QT intervals, according to the American Heart Association 2, 3
Severe toxicity (6-10 mmol/L) presents with hypotension, bradycardia, respiratory depression, complete heart block, and cardiac arrest, as reported by the American College of Cardiology 4, 5

Administer IV calcium (calcium chloride 10% 5-10mL or calcium gluconate 10% 15-30mL) as a physiological antagonist to magnesium's effects, as recommended by the American Heart Association (Class IIb, LOE C) 1, 5
Monitor vital signs, cardiac rhythm, and neurological status closely, as suggested by the American College of Cardiology 2, 3
Consider hemodialysis for patients with severe symptoms unresponsive to calcium and supportive care, especially with renal impairment, as recommended by the National Kidney Foundation 5

Patients with renal impairment are at higher risk for magnesium toxicity even with lower doses, according to the National Kidney Foundation 4
Magnesium toxicity can occur in pregnant women receiving magnesium sulfate for preeclampsia/eclampsia, as reported by the American College of Obstetricians and Gynecologists 4
Certain medications (diuretics, digoxin) may potentiate magnesium toxicity, as warned by the American Heart Association 3

Assess renal function if not previously known, as recommended by the National Kidney Foundation 5
Consider poison control center consultation for complicated cases, as suggested by the American Association of Poison Control Centers 5