FDA Alert Highlights DPD Deficiency Warnings for 5-FU, Capecitabine - Dermatology Advisor

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FDA Alert Highlights DPD Deficiency Warnings for 5-FU, Capecitabine

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February 10, 2026

The Food and Drug Administration (FDA) has issued a safety alert to increase awareness of previous updates to the prescribing label for capecitabine (Xeloda^®) and fluorouracil (5-FU) products related to risks associated with dihydropyrimidine dehydrogenase (DPD) deficiency.

Capecitabine and 5-FU are both nucleoside metabolic inhibitors approved for various cancers. Capecitabine is indicated for colorectal, breast, gastric, esophageal, gastroesophageal junction, and pancreatic cancers, while 5-FU is indicated intravenously for adenocarcinomas of the colon, rectum, breast, stomach, and pancreas, as well as topically for multiple actinic or solar keratoses and superficial basal cell carcinoma. 

According to the safety alert, patients with specific homozygous or compound heterozygous variants in the DYPD gene are at a greater risk for toxicity. These variants lead to a deficiency of the DPD enzyme, which is responsible for breaking down more than 80% of 5-FU. As a result, exposure to capecitabine or 5-FU in these patients can lead to acute early-onset toxicity as well as other serious adverse reactions, such as mucositis, diarrhea, neutropenia, and neurotoxicity.

In response, the FDA approved various safety revisions to the capecitabine and 5-FU product labels. Specifically, a new boxed warning was added to note the risk of serious adverse reactions or death in patients with complete DPD deficiency. The warning further advises that DPYD testing be performed prior to starting capecitabine or 5-FU, unless immediate treatment is necessary. If testing shows complete DPD deficiency, treatment with these nucleoside metabolic inhibitor therapies should be avoided entirely.

The prescribing information was also updated to include a new subsection in the Dosage and Administration and Warnings and Precautions sections to reiterate the need for evaluation and testing for DPD deficiency before starting capecitabine or 5-FU. Moreover, the new labeling highlights the need for caution in those with partial DPD deficiency, emphasizing that dosages for these patients should be individualized and modified based on tolerability and intent of treatment.

The FDA recommends that all health care providers be aware of the risks of DPD deficiency and test for DPYD genetic variants prior to starting treatment, except in cases where immediate treatment is necessary. Additionally, providers should inform patients prior to treatment with capecitabine or 5-FU of the potential toxicities associated with DPD deficiency. 

Adverse reactions associated with the use of capecitabine or 5-FU should be reported to the FDA's MedWatch program.

This article originally appeared on MPR

US Food and Drug Administration. Safety labeling update for capecitabine and fluorouracil (5-FU) on risks associated with dihydropyrimidine dehydrogenase (DPD) deficiency. February 5, 2026. https://www.fda.gov/drugs/resources-information-approved-drugs/safety-labeling-update-capecitabine-and-fluorouracil-5-fu-risks-associated-dihydropyrimidine. 

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Benjamin Hidalgo-Matlock
Skin Care Physicians of Costa Rica

Clinica Victoria en San Pedro: 4000-1054
Momentum Escazu: 2101-9574

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