Brivudine and Fluorouracil: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Fluorouracil
Brivudine
No brand names on record
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
What happens
Increased exposure of 5-fluorouracil
Interaction Deep Dive
Concomitant use of tegafur or tegafur-containing products with dihydropyrimidine dehydrogenase (DPD) inhibitors, such as brivudine and sorivudine, is contraindicated. Inhibition of DPD may lead to clinically significant fluoropyrimidine-related toxicity, with potential fatal outcomes. Do not use tegafur or tegafur-containing products within 4 weeks of the last dose of DPD inhibitors1.
Why it happens (mechanism)
Irreversible inhibition of dihydropyrimidine dehydrogenase by brivudine
Common questions
Can I take Brivudine and Fluorouracil together?
Increased exposure of 5-fluorouracil Always confirm with your pharmacist or prescriber before making any change.
How serious is the Brivudine and Fluorouracil interaction?
It is rated contraindicated. These should generally not be used together.
How quickly could this interaction happen?
The documented onset is "unspecified". The timing of this interaction is not well characterized.
How strong is the evidence for this interaction?
The evidence is graded "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.
Questions for your pharmacist
- Does my dose of Brivudine or Fluorouracil need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there a safer alternative to one of these medications for me?
References (1)
- Product Information: Teysuno oral capsules, tegafur gimeracil oteracil oral capsules. Nordic Group BV (per EMA), Hoofddorp, The Netherlands, 2012.
Keep reading about Fluorouracil
Keep reading about Brivudine
These medications also interact with supplements
Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
major · moderate · minor — check everything you take with our drug–supplement interaction checker.
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