Interferon Alfa-2B Injection and Pirfenidone: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Pirfenidone
Interferon Alfa-2B Injection
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 pirfenidone exposure
Interaction Deep Dive
Coadministration of pirfenidone (a CYP1A2 substrate) and a moderate CYP1A2 inhibitor may increase pirfenidone plasma concentration levels. If concomitant use cannot be avoided, consider reducing the pirfenidone dose1.
Why it happens (mechanism)
Inhibition of CYP1A2-mediated pirfenidone metabolism
Literature reports
1 report — tap to read
a) During drug interaction studies in healthy volunteers (N=27), coadministration of ciprofloxacin 750 mg/day from day 2 to day 7 and pirfenidone 801 mg on day 6 resulted in an 81% increase in pirfenidone exposure 2.
Common questions
Can I take Interferon Alfa-2B Injection and Pirfenidone together?
Increased pirfenidone exposure Always confirm with your pharmacist or prescriber before making any change.
How serious is the Interferon Alfa-2B Injection and Pirfenidone 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 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 Interferon Alfa-2B Injection or Pirfenidone 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 (2)
- Product Information: ESBRIET(R) oral capsules, oral tablets, pirfenidone oral capsules, oral tablets. Genentech USA, Inc (per manufacturer), South San Francisco, CA, 2017. DailyMed
- Product Information: ESBRIET(R) oral capsules, pirfenidone oral capsules. InterMune, Inc. (per Manufacturer), Brisbane, CA, 2014. DailyMed
Keep reading about Pirfenidone
Keep reading about Interferon Alfa-2B Injection
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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