5-fluorouracil and capecitabine are chemotherapeutic agents commonly used to treat solid malignancies. Increased susceptibility to 5-fluorouracil or capecitabine, caused by impaired clearance, dihydropyrimidine dehydrogenase deficiency, or other genetic mutations in the enzymes that metabolize 5-fluorouracil can lead to severe life-threatening toxicities and are typically manifested by an early onset of symptoms. We report and discuss the management and outcome of capecitabine toxicity with the recently FDA approved antidote, uridine triacetate (Vistogard), in a 57-year-old female breast cancer patient with homozygous dihydropyrimidine dehydrogenase deficiency who received treatment beyond the recommended 96 h window from the last dose of capecitabine.