Magnesium sulfate is the standard of care for seizure prevention in moderate to severe preeclampsia and is also used to treat eclamptic seizures. It acts as a central nervous system depressant by blocking neuromuscular transmission and reducing cerebral irritability, thereby lowering the risk of seizures. It is administered intravenously with a loading dose followed by a continuous infusion. Because magnesium can accumulate and cause toxicity, regular monitoring is essential—including checking deep tendon reflexes, respiratory rate, and urine output. Loss of reflexes is often the earliest sign of toxicity and may require dose adjustment or discontinuation.