Which adverse effect is expected with intravenous magnesium sulfate therapy?

Which adverse effect is expected with intravenous magnesium sulfate therapy?

• A. Flushing
• B. Hypertension
• C. Increased urine output
• D. Depressed respirations

Answer: (D)

Respiratory depression is the expected adverse effect with IV magnesium sulfate. Magnesium acts as a CNS depressant and neuromuscular blocker; when levels rise, the respiratory drive and reflexes can be suppressed, leading to slowed or shallow breathing. Because of this, you monitor respiratory rate and pattern, deep tendon reflexes, urine output, and blood pressure closely. If signs of toxicity appear—such as absent deep tendon reflexes or a respiratory rate that is too low—hold the infusion and notify the clinician, with calcium gluconate available as the antidote. Flushing, hypertension, or increased urine output aren’t the typical adverse effects of magnesium sulfate at therapeutic doses; vasodilation can cause hypotension, and increased urine output is not a defining response.

Respiratory depression is the expected adverse effect with IV magnesium sulfate. Magnesium acts as a CNS depressant and neuromuscular blocker; when levels rise, the respiratory drive and reflexes can be suppressed, leading to slowed or shallow breathing. Because of this, you monitor respiratory rate and pattern, deep tendon reflexes, urine output, and blood pressure closely. If signs of toxicity appear—such as absent deep tendon reflexes or a respiratory rate that is too low—hold the infusion and notify the clinician, with calcium gluconate available as the antidote. Flushing, hypertension, or increased urine output aren’t the typical adverse effects of magnesium sulfate at therapeutic doses; vasodilation can cause hypotension, and increased urine output is not a defining response.