Drug interactions
Fluoxetine + Valbenazine
Severity: Major
Fluoxetine and Valbenazine: major interaction.
Last updated
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Fluoxetine strongly inhibits CYP2D6, which raises exposure to the active metabolite of valbenazine and increases the risk of somnolence and QT prolongation. Both drugs have QT effects.
What this interaction means in plain words
Fluoxetine and Valbenazine can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Fluoxetine belongs to Central Nervous System; Valbenazine belongs to Central Nervous System.
Why it happens
CYP2D6 inhibition reduces clearance of valbenazine's active metabolite, with additive QT prolongation.
What to do
Reduce the valbenazine dose in line with labeling for strong CYP2D6 inhibitors. Monitor for sedation and obtain an ECG in patients with cardiac risk.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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Other interactions of Fluoxetine
- Fluoxetine + Isocarboxazid Contraindicated
- Fluoxetine + Mavacamten Contraindicated
- Fluoxetine + Methylene blue Contraindicated
- Fluoxetine + Phenelzine Contraindicated
- Fluoxetine + Pimozide Contraindicated
- Fluoxetine + Rasagiline Contraindicated
Other interactions of Valbenazine
- Deutetrabenazine + Valbenazine Contraindicated
- Tranylcypromine + Valbenazine Contraindicated
- Amiodarone + Valbenazine Major
- Amisulpride + Valbenazine Major
- Apalutamide + Valbenazine Major
- Carbamazepine + Valbenazine Major
Frequently asked questions
Can I take Fluoxetine with Valbenazine?
MediHelp rates the interaction as major. Fluoxetine and Valbenazine can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Fluoxetine strongly inhibits CYP2D6, which raises exposure to the active metabolite of valbenazine and increases the risk of somnolence and QT prolongation. Both drugs have QT effects.
How serious is the interaction between Fluoxetine and Valbenazine?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Reduce the valbenazine dose in line with labeling for strong CYP2D6 inhibitors. Monitor for sedation and obtain an ECG in patients with cardiac risk.
What other medicines interact with Fluoxetine?
MediHelp also lists interactions of Fluoxetine with, for example, Isocarboxazid, Mavacamten, Methylene blue. The full list is on the Fluoxetine page.
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