The FDA issued a safety communication clarifying that the DPYD (dihydropyrimidine dehydrogenase) deficiency labeling update applies to both capecitabine (Xeloda) and intravenous 5‑fluorouracil (5‑FU). The agency advised clinicians to inform patients about toxicity risks and to test for DPD deficiency unless treatment is urgent. This guidance aims to reduce severe treatment‑related toxicities by improving patient selection and preemptive dose modifications. Oncology clinics, laboratories and sponsors of fluoropyrimidine regimens will need to operationalize testing pathways and update informed‑consent materials. Payers and diagnostic developers may see increased demand for DPYD assays as sites align with the FDA’s communication.