Fluorouracil and Levoleucovorin interaction
Fluorouracil and Levoleucovorin: the Levoleucovorin prescribing label flags this combination with the strongest language, such as a contraindication, a boxed warning, or an instruction to avoid it.
Do not combine without a prescriber's guidance. The label language below is the strongest FDA uses.
What the FDA labels say
From the Levoleucovorin (KHAPZORY) label · effective 2026-03-17
Deaths from severe enterocolitis, diarrhea, and dehydration have occurred in elderly patients receiving weekly d,l- leucovorin and fluorouracil.
Increased Gastrointestinal Toxicities with Fluorouracil : Do not initiate or continue therapy with KHAPZORY and fluorouracil in patients with symptoms of gastrointestinal toxicity until symptoms have resolved.
Increased Gastrointestinal Toxicities with Fluorouracil Leucovorin products increase the toxicities of fluorouracil [see Drug Interactions ( 7 )] .
Do not initiate or continue therapy with KHAPZORY and fluorouracil in patients with symptoms of gastrointestinal toxicity until those symptoms have resolved.
Fluorouracil Leucovorin products increase the toxicity of fluorouracil.
Taking more than these two? Interactions stack. Check your whole list at once; it stays in your browser.
Open in the checkerNot medical advice. Interaction Checker quotes FDA label text and NIH fact sheets. Whether an interaction matters for you depends on doses, timing, kidney and liver function, and other conditions. Confirm with a pharmacist or prescriber.