Hyperglycemia and hyperosmolar state: Dextrose given faster than the body can use it raises blood glucose and serum osmolality. This can cause osmotic diuresis, dehydration, electrolyte loss, coma, and rarely death, particularly in diabetes, critical illness, renal impairment, and neonates. The current dextrose label specifically warns of this risk.

Dilutional hyponatremia: Solutions such as D5W become physiologically hypotonic once glucose is metabolized, effectively leaving free water. In patients with high ADH levels, such as postoperative, pain, nausea, CNS disease, or children, this may lower sodium, causing cerebral edema, seizures, or death. Miller's Anesthesia, p. 6355 notes the hyponatremia risk of dextrose solutions; postoperative hyponatremia is especially associated with electrolyte-free water and D5W. Comprehensive Clinical Nephrology, p. 648.

Concentrated products are dangerous: D10, D25, and particularly D50 are hypertonic. Extravasation can cause severe local tissue injury, and administration errors can produce abrupt extreme hyperglycemia. They require careful route, dilution, and monitoring.

Fluid overload and electrolyte disturbance: Giving excess volume can worsen heart failure, kidney failure, pulmonary edema, and electrolyte imbalance.

Medication-safety risk: Dextrose fluids can look similar to other IV bags, and confusing D5W with saline or using the wrong concentration can lead to an inappropriate resuscitation or maintenance fluid choice.