Drug Interaction Report

Dacomitinib and Duloxetine: Interaction Details

A pharmacist-reviewed analysis of the Dacomitinib and Duloxetine interaction: the documented clinical effects, severity rating, onset, mechanism, and management considerations, with cited references throughout.

AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature

Duloxetine

No brand names on record
+

Dacomitinib

Vizimpro Vizimpro®
Dr. Brian Staiger, PharmD, BCPS
Medically reviewed by
Dr. Brian Staiger, PharmD, BCPS
Updated Aug 8, 2026
Editorial policy · Data sources
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Interaction severity
Major
Potentially serious — often needs a change or close monitoring.
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.

Of 56 documented Dacomitinib interactions, 43 are rated major — including this one.
Worried about symptoms right now? Contact your pharmacist or prescriber, or call Poison Control at 1-800-222-1222 (US). Call 911 for an emergency.
Onset
unspecified
Evidence
probable
Severity
Major

What happens

Increased DULoxetine exposure and an increased risk of DULoxetine-related adverse effects

Interaction Deep Dive

Concomitant use of DULoxetine with potent inhibitors of CYP2D6 may result in higher concentrations of DULoxetine. Coadministration of DULoxetine 40 mg once daily with another potent CYP2D6 inhibitor (PARoxetine 20 mg once daily) resulted in a 60% increase in the serum concentration of DULoxetine1. Greater degrees of inhibition are expected with higher doses of CYP2D6 inhibitors. Exercise caution when coadministering DULoxetine delayed-release capsules and potent CYP2D6 inhibitors 2.

Why it happens (mechanism)

Inhibition of CYP2D6-mediated metabolism of DULoxetine

Literature reports

1 report — tap to read

a) Coadministration of DULoxetine 40 mg once daily with another potent CYP2D6 inhibitor (paroxetine 20 mg once daily) resulted in a 60% increase in the serum concentration of DULoxetine 12.

Common questions

Can I take Dacomitinib and Duloxetine together?

Increased DULoxetine exposure and an increased risk of DULoxetine-related adverse effects Always confirm with your pharmacist or prescriber before making any change.

How serious is the Dacomitinib and Duloxetine 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 "probable". Good supporting evidence, though not definitively proven.

From our Q&A

Real reader questions about these medications, each personally answered by our pharmacist:

Questions for your pharmacist

  • Does my dose of Dacomitinib or Duloxetine 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)

  1. Product Information: CYMBALTA(R) oral delayed-release capsules, duloxetine oral delayed-release capsules. Lilly USA LLC (per FDA), Indianapolis, IN, 2023. DailyMed
  2. Product Information: DRIZALMA SPRINKLE(TM) oral delayed-release capsules, duloxetine oral delayed-release capsules. Sun Pharmaceuticals Industries Inc (per FDA), Cranbury, NJ, 2023. DailyMed
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Duloxetine

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Dacomitinib

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All Dacomitinib interactions (56) Dacomitinib drug information
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Beyond drug–drug

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:

Duloxetine + Activated Charcoal Beer Lithium Siberian Cocklebur Wine 1,3-dmaa 5-htp Acacia Rigidula + 124 more
Dacomitinib + Activated Charcoal Coffee Charcoal European Mandrake Fever Bark Glucomannan Guar Gum Gum Arabic Iboga + 12 more

major · moderate · minor — check everything you take with our drug–supplement interaction checker.

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This information is for education, not a substitute for professional medical advice. Do not start, stop, or change any medication without talking to your pharmacist or prescriber.