Painful intramuscular injection.
Excessive administration of magnesium sulfate may result in hypermagnesemia. The signs of hypermagnesemia may include: nausea, vomiting, flushing, hypotension, muscle weakness, muscle paralysis, blurred or double vision, CNS depression and loss of reflexes.
More severe hypermagnesemia may result in respiratory depression, respiratory paralysis, renal failure, coma, cardiac arrhythmias and cardiac arrest.
Hypocalemia with tetany, secondary to hypermagnesemia, has been reported.