Human milk is associated with substantial benefits to infants' health and development, especially in premature infants. Some mothers are unable or unwilling to provide breast milk to their infant. The use of donor human milk as an alternative to cow milk in these infants has risen dramatically in the past year. However, there have been recent reports of hyperphosphatemia and hyponatremia associated with the consumption of donor human milk products. These electrolyte imbalances can lead to concerning symptoms, including headache, nausea, vomiting, altered mental status, coma, seizures, or heart failure. It is important to recognize and appropriately treat these electrolyte disturbances associated with donor human milk to avoid potential nutritional problems.