Leucovorin and Levoleucovorin interaction
Leucovorin and Levoleucovorin: both prescribing labels flag 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 Leucovorin (VYKOURA) label · effective 2026-03-12
VYKOURA is contraindicated in patients who have had a severe hypersensitivity reaction to leucovorin (folinic acid), levoleucovorin, or folic acid [see Warnings and Precautions (5.1) ].
VYKOURA is contraindicated in patients who have had a severe hypersensitivity reaction to leucovorin, levoleucovorin, or folic acid [see Contraindications (4) ].
From the Levoleucovorin (KHAPZORY) label · effective 2026-03-17
KHAPZORY is contraindicated in patients who have had severe hypersensitivity to leucovorin products, folic acid, or folinic acid [see Adverse Reactions ( 6.2 )] .
Patients who have had severe hypersensitivity reactions to leucovorin products, folic acid, or folinic acid.
Deaths from severe enterocolitis, diarrhea, and dehydration have occurred in elderly patients receiving weekly d,l- leucovorin and fluorouracil.
Drug Interaction with Trimethoprim-Sulfamethoxazole : Increased rates of treatment failure and morbidity with concomitant use of d, l -leucovorin with trimethoprim-sulfamethoxazole for Pneumocystis jiroveci pneumonia in patients with HIV.
Increased Gastrointestinal Toxicities with Fluorouracil Leucovorin products increase the toxicities of fluorouracil [see Drug Interactions ( 7 )] .
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.