Fluvoxamine and Abrocitinib: 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
Fluvoxamine
No brand names on recordAbrocitinib
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. Fluvoxamine slows down a liver enzyme (called CYP2C19) that your body uses to break down abrocitinib (Cibinqo), the medicine for your eczema. When that enzyme is slowed, more abrocitinib builds up in your body. In studies, levels roughly doubled.
More medicine in your system can mean a higher chance of side effects. The good news is this is very manageable. Your doctor already knows how to handle it, usually by lowering your abrocitinib dose while keeping it working well. Don't stop or change anything on your own, just check in with your pharmacist or doctor so they can tailor the dose for you.
Mechanism: Fluvoxamine is a strong CYP2C19 inhibitor; abrocitinib is a CYP2C19 substrate. Inhibition reduces clearance, increasing exposure of abrocitinib and its active metabolites (neither is a prodrug requiring activation, so effect is increased, not reduced).
Magnitude: ~33% increase in Cmax and ~91% increase in AUC of active moiety.
Evidence: Theoretical/PK-based; major severity. Onset unspecified.
- Reduce abrocitinib to 50 mg once daily with a strong CYP2C19 inhibitor.
- If inadequate response after 12 weeks, may increase to 100 mg once daily.
- Discontinue if inadequate response persists after the increase.
- Monitor for JAK-inhibitor toxicities (cytopenias, infection).
What happens
Increased abrocitinib and active metabolite exposure
Interaction Deep Dive
When abrocitinib is given together with potent CYP2C19 inhibitors, the exposure to abrocitinib and its active metabolites rises. For instance, combining fluvoxamine, a strong CYP2C19 inhibitor, with abrocitinib produced a 33% rise in Cmax and a 91% rise in AUC for abrocitinib and its active metabolites. For individuals receiving strong CYP2C19 inhibitors, the abrocitinib dose should be lowered to 50 mg taken once daily. Should the response prove insufficient following 12 weeks, an increase to 100 mg orally once daily may be considered. Treatment should be stopped if the response remains inadequate even after the dose has been raised to 100 mg once daily1.
Why it happens (mechanism)
Inhibition of CYP2C19-mediated abrocitinib metabolism
How to manage this interaction
This is manageable with a simple dose plan. Because fluvoxamine raises abrocitinib levels, your care team will individualize your abrocitinib dose.
- Keep taking both medicines exactly as prescribed unless your doctor tells you otherwise.
- The usual approach is to reduce abrocitinib to 50 mg once daily while you're on fluvoxamine.
- If your eczema isn't well controlled after about 12 weeks, your doctor may increase the dose to 100 mg once daily.
- Tell your pharmacist or prescriber that you take both drugs, and report any unusual symptoms like signs of infection, unusual bruising, or feeling very tired.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
1 report — tap to read
a) When abrocitinib 100 mg was given together with fluvoxamine (a strong CYP2C19 and moderate CYP3A inhibitor) 50 mg once daily over 9 days, the Cmax and AUC(infinity) of abrocitinib along with its metabolites M1 and M2 rose by 1.33-fold and 1.91-fold, respectively 1.
Common questions
Can I take Fluvoxamine and Abrocitinib together?
Fluvoxamine roughly doubles abrocitinib exposure by blocking CYP2C19, so your doctor will typically lower abrocitinib to 50 mg once daily; keep taking both as prescribed and confirm the plan with your care team. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Fluvoxamine and Abrocitinib 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 Fluvoxamine and Abrocitinib interaction managed?
This is manageable with a simple dose plan. Because fluvoxamine raises abrocitinib levels, your care team will individualize your abrocitinib dose. Keep taking both medicines exactly as prescribed unless your doctor tells you otherwise. The usual approach is to reduce abrocitinib to 50 mg once daily while you're on fluvoxamine. If your eczema isn't well controlled after about 12 weeks, your doctor… 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 Fluvoxamine or Abrocitinib 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: CIBINQO(TM) oral tablets, abrocitinib oral tablets. Pfizer Labs (per FDA), New York, NY, 2022. DailyMed
Keep reading about Fluvoxamine
Keep reading about Abrocitinib
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