Interferon Alfa-2B Injection and Fezolinetant: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Interferon Alfa-2B Injection
Fezolinetant
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 fezolinetant exposure
Interaction Deep Dive
Coadministration of fezolinetant (a CYP1A2 substrate) with strong, moderate or weak CYP1A2 inhibitors increases the plasma concentrations of fezolinetant and is hence contraindicated. Data from clinical studies and model-informed approaches indicate that fezolinetant Cmax increased by 80% and AUC increased by 840% following concomitant use with fluvoxamine (a strong CYP1A2 inhibitor). Fezolinetant Cmax increased by 40% and AUC increased by 360% following concomitant use with mexiletine (a moderate CYP1A2 inhibitor) 400 mg every 8 hours. Fezolinetant Cmax increased by 30% and AUC increased by 100% following concomitant use with cimetidine (a weak CYP1A2 inhibitor) 300 mg every 6 hours1.
Why it happens (mechanism)
Inhibition of CYP1A2-mediated metabolism of fezolinetant
Literature reports
3 reports — tap to read
a) Data from clinical studies and model-informed approaches indicate that fezolinetant Cmax increased by 80% and AUC increased by 840% following concomitant use with fluvoxamine (a strong CYP1A2 inhibitor) 1.
b) Fezolinetant Cmax increased by 40% and AUC increased by 360% following concomitant use with mexiletine (a moderate CYP1A2 inhibitor) 400 mg every 8 hours 1.
c) Fezolinetant Cmax increased by 30% and AUC increased by 100% following concomitant use with cimetidine (a weak CYP1A2 inhibitor) 300 mg every 6 hours 1.
Common questions
Can I take Interferon Alfa-2B Injection and Fezolinetant together?
Increased fezolinetant exposure Always confirm with your pharmacist or prescriber before making any change.
How serious is the Interferon Alfa-2B Injection and Fezolinetant 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 "probable". Good supporting evidence, though not definitively proven.
Questions for your pharmacist
- Does my dose of Interferon Alfa-2B Injection or Fezolinetant 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: Veozah(TM) oral tablets, fezolinetant oral tablets. Astellas Pharma US, Inc, Northbrook, IL, 2023. DailyMed
Keep reading about Interferon Alfa-2B Injection
Keep reading about Fezolinetant
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