Valbenazine and Dacomitinib: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Valbenazine
Dacomitinib
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 valbenazine exposure and its active metabolite and an increased risk of valbenazine and its active metabolite-related adverse reactions
Interaction Deep Dive
Concomitant use of valbenazine with a strong CYP2D6 inhibitor may increase exposure of the active metabolite (alpha-HTBZ is a CYP2D6 substrate) and may result in a significant prolongation of the QT interval. During coadministration, reduce valbenazine dosage to 40 mg once daily1.
Why it happens (mechanism)
Inhibition of CYP2D6-mediated metabolism of valbenazine
Literature reports
1 report — tap to read
a) In a pharmacokinetic study, coadministration of valbenazine with PARoxetine (a strong CYP2D6 inhibitor) increased exposure of both valbenazine and the active metabolite, alpha-dihydrotetrabenazine, by approximately 1- to 2-fold 1.
Common questions
Can I take Valbenazine and Dacomitinib together?
Increased valbenazine exposure and its active metabolite and an increased risk of valbenazine and its active metabolite-related adverse reactions Always confirm with your pharmacist or prescriber before making any change.
How serious is the Valbenazine and Dacomitinib 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.
Questions for your pharmacist
- Does my dose of Valbenazine or Dacomitinib 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: INGREZZA(R) oral capsules, valbenazine oral capsules. Neurocrine Biosciences Inc (per FDA), San Diego, CA, 2023. DailyMed
Keep reading about Valbenazine
Keep reading about Dacomitinib
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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