The FDA issued a safety communication expanding DPYD-related labeling to encompass both capecitabine (Xeloda) and intravenous 5‑fluorouracil (5‑FU), urging clinicians to assess dihydropyrimidine dehydrogenase (DPD) deficiency risk and consider testing prior to initiating therapy unless immediate treatment is required. The agency advised clinicians to discuss toxicity risks with patients and to monitor for signs of severe adverse reactions linked to DPD deficiency, which impairs catabolism of fluoropyrimidines and can cause life‑threatening toxicity. The update has immediate implications for oncology prescribing pathways and for laboratories offering pre‑treatment pharmacogenetic screening. Clarification: DPD deficiency reduces the capacity to metabolize fluoropyrimidines and testing can guide dose adjustments to avoid severe toxicity.