5-fluorouracil (5-FU) is a pyrimidine analogue used to treat adults with a variety of carcinomas but less frequently used in pediatrics. 5-FU is a well-recognized cardiotoxic chemotherapy medications, particularly among adults with underlying cardiovascular disease, however this has rarely been reported in the pediatric population. We report a rare case of 5-FU induced cardiomyopathy in a pediatric patient with nasopharyngeal carcinoma (NPC), successfully managed with milrinone and uridine triacetate, underscoring the need for awareness and prompt recognition and medication administration for this potentially reversible condition.