Which of the following indicates a serious side effect of magnesium sulfate?

• A. Lethargy
• B. Visual blurring
• C. Headache
• D. Weight gain

Answer: (A)

Lethargy is indeed a serious side effect of magnesium sulfate. It can indicate that the serum magnesium levels are too high, potentially leading to magnesium toxicity. Symptoms such as lethargy suggest that the central nervous system is being affected, which is a concern in patients receiving this medication for conditions like preeclampsia or eclampsia. Monitoring for lethargy is crucial, as it may require prompt adjustment of the magnesium sulfate dosage or even cessation of treatment to protect the patient from further complications related to excess magnesium in the bloodstream.

Visual blurring, headache, and weight gain can occur with magnesium sulfate use, but they are generally less indicative of serious side effects. Visual blurring may be related to changes in blood pressure or fluid balance rather than direct magnesium toxicity. Headaches may also arise from various causes that are not directly linked to the magnesium levels, and weight gain could result from fluid retention, which is common in pregnant patients and may not be a direct consequence of magnesium sulfate. Therefore, while they can be concerning, they do not signal the immediate danger associated with lethargy.