Abrocitinib and Doxifluridine: Interaction Details
AI-assisted, pharmacist-reviewed · AI content regenerated Jul 11, 2026 · Source data updated Jul 10, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Abrocitinib
Doxifluridine
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.
Here's what's going on. Doxifluridine is a cancer medicine that can slow down a liver enzyme called CYP2C9. Abrocitinib (Cibinqo), your eczema medicine, is partly cleared by that same enzyme. When the enzyme is slowed, abrocitinib can build up in your body a bit more than usual, which could make its side effects (like nausea, headache, or a higher chance of infection) more likely.
The good news: this concern is based on theory, not real-world reports. Please keep taking both exactly as prescribed and let your care team know you take them together. They can watch you more closely and adjust things if needed.
Mechanism: Doxifluridine (a prodrug in the capecitabine/5-FU family) inhibits CYP2C9. Abrocitinib is partly metabolized by CYP2C9, so inhibition may reduce its clearance and increase exposure (AUC/Cmax), raising the risk of dose-related adverse effects.
- Direction: increased abrocitinib effect/toxicity
- Onset: unspecified
- Evidence: theoretical
- Severity: major
Management: Monitor closely for abrocitinib-related adverse effects (cytopenias, infection, GI effects, thromboembolic signs). Dose may need to be individualized by the care team; consider closer clinical and lab monitoring while coadministered.
What happens
Increased exposure of CYP2C9 substrates and an increased risk of CYP2C9 substrates-related adverse effects
Interaction Deep Dive
When capecitabine, doxifluridine, fluorouracil (both prodrugs of capecitabine), or tegafur (a prodrug of fluorouracil) are given together with CYP2C9 substrates, exposure to those CYP2C9 substrates may rise, potentially heightening the risk of adverse reactions associated with them. For CYP2C9 substrates in which even small changes in concentration can produce serious adverse reactions, monitor closely for such reactions during concomitant use with capecitabine, doxifluridine, fluorouracil, or tegafur1.
Why it happens (mechanism)
Inhibition of CYP2C9-mediated metabolism of CYP2C9 substrates
How to manage this interaction
Keep taking both medicines as prescribed unless your care team tells you otherwise. The main step here is closer watching, since even small increases in abrocitinib levels could matter.
- Tell your pharmacist and prescriber you take abrocitinib and doxifluridine together.
- Your team may monitor you more closely (bloodwork and how you feel), and your abrocitinib dose may need to be adjusted and individualized.
- Report new or worse side effects like unusual bruising, signs of infection, nausea, or headache.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
1 report — tap to read
a) Giving multiple doses of capecitabine (1000 mg/m(2) twice daily for 14 days) at the same time raised the AUC of celecoxib (a CYP2D6 substrate) by 28%, its Cmax by 24%, and its Ctrough by 30% 1.
Common questions
Can I take Abrocitinib and Doxifluridine together?
Doxifluridine may slow the breakdown of abrocitinib and raise its levels, so your care team may monitor you more closely and adjust the dose if needed. This is a theoretical concern, so keep taking both as prescribed and flag any new side effects. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Abrocitinib and Doxifluridine interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "unspecified". The timing of this interaction is not well characterized.
How is the Abrocitinib and Doxifluridine interaction managed?
Keep taking both medicines as prescribed unless your care team tells you otherwise. The main step here is closer watching, since even small increases in abrocitinib levels could matter. Tell your pharmacist and prescriber you take abrocitinib and doxifluridine together. Your team may monitor you more closely (bloodwork and how you feel), and your abrocitinib dose may need to be adjusted and indivi… Management is individual — always follow your own care team's guidance.
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 Abrocitinib or Doxifluridine 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: XELODA(R) oral tablets, capecitabine oral tablets. Genentech USA Inc (per FDA), South San Francisco, CA, 2022. DailyMed
Keep reading about Abrocitinib
Keep reading about Doxifluridine
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.
Check another combination
Our instant two-drug interaction checker is almost here.
Still have questions about this combination?
Every question gets a real answer from a licensed pharmacist — free, and usually within a day.
Ask the pharmacist