Novel Cause of Reversible Leukoencephalopathy in an Infant Associated With Illicit Fentanyl Exposure.

Fentanyl is a potent opioid anesthetic and analgesic whose illicit use has been linked to a significant increase in mortality and morbidity, affecting not only adults but also children through accidental exposure. We present a case of a 12-month-old normally developing baby girl who was admitted for hypothermia, acute hypoxic respiratory failure, altered mental status, and metabolic acidosis. A comprehensive workup confirmed the presence of fentanyl in her urine.