Abrocitinib and Tegafur: 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
Tegafur
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 when you take tegafur and abrocitinib (Cibinqo) together. Tegafur can slow down a liver enzyme called CYP2C9. Abrocitinib is broken down partly by that same enzyme, so when it is slowed, abrocitinib may build up in your body a bit more than usual. That could mean a higher chance of side effects.
I want to reassure you that this is a theoretical concern, meaning it is based on how these drugs work rather than on real reports of problems. Your care team can manage it easily by watching you more closely and adjusting your dose if needed. Keep taking both as prescribed, and check in with your pharmacist or doctor.
Mechanism: Tegafur (a fluorouracil prodrug) inhibits CYP2C9, reducing metabolism of CYP2C9 substrates. Abrocitinib is metabolized in part by CYP2C9, so coadministration may increase abrocitinib exposure (AUC/Cmax) and the risk of substrate-related adverse effects.
Direction: Increased abrocitinib effect/toxicity risk (e.g., cytopenias, infection risk, thromboembolic events).
- Onset: unspecified
- Evidence: theoretical
- Severity: major
Management: Monitor closely for abrocitinib-related adverse reactions; dose may need individualization by the care team. Given abrocitinib's narrow safety margin, even modest concentration changes warrant vigilance.
What happens
Increased exposure of CYP2C9 substrates and an increased risk of CYP2C9 substrates-related adverse effects
Interaction Deep Dive
When capecitabine, doxifluridine, or fluorouracil (both prodrugs of capecitabine), or tegafur (a prodrug of fluorouracil) are given together with CYP2C9 substrates, the exposure to those CYP2C9 substrates may rise, potentially heightening the likelihood of adverse reactions associated with them. For CYP2C9 substrates in which even small changes in concentration can produce serious adverse reactions, closely watch for such reactions during concurrent use with capecitabine, doxifluridine, fluorouracil, or tegafur1.
Why it happens (mechanism)
Inhibition of CYP2C9-mediated metabolism of CYP2C9 substrates
How to manage this interaction
Good news: this is manageable, and you should not stop either medicine on your own.
- Keep taking both as prescribed unless your prescriber tells you otherwise.
- Your care team may monitor you more closely for side effects of abrocitinib.
- Your abrocitinib dose may need to be adjusted and individualized by your team.
- Report anything new, such as signs of infection, unusual bruising or bleeding, tiredness, or leg swelling.
Ask your pharmacist or doctor to review this combination so they can decide on the right monitoring or dosing for you.
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 celecoxib (a CYP2D6 substrate) AUC by 28%, Cmax by 24%, and Ctrough by 30% 1.
Common questions
Can I take Abrocitinib and Tegafur together?
Tegafur can slow the breakdown of abrocitinib, potentially raising its levels and side-effect risk, though this concern is theoretical. Keep taking both as prescribed and let your care team monitor you and adjust the dose if needed. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Abrocitinib and Tegafur 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 Tegafur interaction managed?
Good news: this is manageable, and you should not stop either medicine on your own. Keep taking both as prescribed unless your prescriber tells you otherwise. Your care team may monitor you more closely for side effects of abrocitinib. Your abrocitinib dose may need to be adjusted and individualized by your team. Report anything new, such as signs of infection, unusual bruising or bleeding, tiredn… 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 Tegafur 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 Tegafur
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