Hyponatremia is a common electrolyte abnormality affecting hospitalized patients.1 It is an independent predictor for mortality and is associated with increased length of hospital stay and higher costs. The most serious potential complication is hyponatremic encephalopathy, a medical emergency that can result in death or irreversible brain injury if inadequately treated.2 Hypertonic saline is a safe and effective means of correcting hyponatremia.2-4 A rare yet serious complication from excessive correction of chronic hyponatremia is the development of cerebral demyelination.