Drug interactions
Promethazine + Propafenone
Severity: Moderate
Promethazine and Propafenone: 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
Promethazine is metabolized partly by CYP2D6, and propafenone is a CYP2D6 inhibitor, so promethazine exposure may rise. Both drugs can also affect cardiac conduction, which adds concern for QT or arrhythmia effects.
What this interaction means in plain words
Promethazine and Propafenone 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.
Promethazine belongs to Respiratory; Propafenone belongs to Cardiovascular.
Why it happens
Propafenone inhibits CYP2D6, reducing promethazine clearance, with possible additive effects on cardiac conduction.
What to do
Monitor for increased sedation and anticholinergic effects, and consider an ECG if other QT-prolonging drugs or cardiac disease are present. Reduce the promethazine dose if adverse effects appear.
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
- Ibutilide + Promethazine Contraindicated
- Pimozide + Promethazine Contraindicated
- Promethazine + Thioridazine Contraindicated
- Alfentanil + Promethazine Major
- Amiodarone + Promethazine Major
- Amisulpride + Promethazine Major
Other interactions of Propafenone
- Dofetilide + Propafenone Contraindicated
- Dronedarone + Propafenone Contraindicated
- Nilotinib + Propafenone Contraindicated
- Nirmatrelvir / ritonavir + Propafenone Contraindicated
- Nirmatrelvir + Propafenone Contraindicated
- Pimozide + Propafenone Contraindicated
Frequently asked questions
Can I take Promethazine with Propafenone?
MediHelp rates the interaction as moderate. Promethazine and Propafenone 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. Promethazine is metabolized partly by CYP2D6, and propafenone is a CYP2D6 inhibitor, so promethazine exposure may rise. Both drugs can also affect cardiac conduction, which adds concern for QT or arrhythmia effects.
How serious is the interaction between Promethazine and Propafenone?
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 increased sedation and anticholinergic effects, and consider an ECG if other QT-prolonging drugs or cardiac disease are present. Reduce the promethazine dose if adverse effects appear.
What other medicines interact with Promethazine?
MediHelp also lists interactions of Promethazine with, for example, Ibutilide, Pimozide, Thioridazine. The full list is on the Promethazine page.
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