Drug interactions
Fluvoxamine + Promethazine
Severity: Moderate
Fluvoxamine and Promethazine: moderate 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
Fluvoxamine has a modest QT-prolonging potential, and promethazine can also prolong the QT interval. Fluvoxamine strongly inhibits CYP1A2 and CYP2C19 and moderately inhibits CYP2D6, which could raise promethazine exposure and increase sedation and cardiac risk.
What this interaction means in plain words
Fluvoxamine and Promethazine can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Fluvoxamine belongs to Central Nervous System; Promethazine belongs to Respiratory.
Why it happens
Additive QT prolongation and fluvoxamine inhibition of CYP2D6 metabolism of promethazine.
What to do
Monitor for excessive sedation and, in patients with other QT risk factors, obtain an ECG and correct electrolytes. Consider a lower promethazine dose.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Promethazine
- Cabergoline + Promethazine Contraindicated
- Dopamine + Promethazine Contraindicated
- Ibutilide + Promethazine Contraindicated
- Pimozide + Promethazine Contraindicated
- Promethazine + Thioridazine Contraindicated
- Alfentanil + Promethazine Major
Other interactions of Fluvoxamine
- Agomelatine + Fluvoxamine Contraindicated
- Alosetron + Fluvoxamine Contraindicated
- Fezolinetant + Fluvoxamine Contraindicated
- Fluvoxamine + Isocarboxazid Contraindicated
- Fluvoxamine + Mavacamten Contraindicated
- Fluvoxamine + Methylene blue Contraindicated
Frequently asked questions
Can I take Fluvoxamine with Promethazine?
MediHelp rates the interaction as moderate. Fluvoxamine and Promethazine can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Fluvoxamine has a modest QT-prolonging potential, and promethazine can also prolong the QT interval. Fluvoxamine strongly inhibits CYP1A2 and CYP2C19 and moderately inhibits CYP2D6, which could raise promethazine exposure and increase sedation and cardiac risk.
How serious is the interaction between Fluvoxamine and Promethazine?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor for excessive sedation and, in patients with other QT risk factors, obtain an ECG and correct electrolytes. Consider a lower promethazine dose.
What other medicines interact with Promethazine?
MediHelp also lists interactions of Promethazine with, for example, Cabergoline, Dopamine, Ibutilide. The full list is on the Promethazine page.
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