Drug interactions
Promethazine + Venlafaxine
Severity: Moderate
Promethazine and Venlafaxine: 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
Venlafaxine is a weak CYP2D6 inhibitor, so any rise in promethazine exposure is likely small. Venlafaxine can also prolong QT at higher doses, so combined effects on the heart and CNS are possible.
What this interaction means in plain words
Promethazine and Venlafaxine 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; Venlafaxine belongs to Central Nervous System.
Why it happens
Weak CYP2D6 inhibition by venlafaxine and possible additive QT prolongation.
What to do
Monitor for sedation and palpitations, and obtain an ECG if other QT risk factors are present.
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 Venlafaxine
- Isocarboxazid + Venlafaxine Contraindicated
- Methylene blue + Venlafaxine Contraindicated
- Phenelzine + Venlafaxine Contraindicated
- Procarbazine + Venlafaxine Contraindicated
- Rasagiline + Venlafaxine Contraindicated
- Safinamide + Venlafaxine Contraindicated
Frequently asked questions
Can I take Promethazine with Venlafaxine?
MediHelp rates the interaction as moderate. Promethazine and Venlafaxine 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. Venlafaxine is a weak CYP2D6 inhibitor, so any rise in promethazine exposure is likely small. Venlafaxine can also prolong QT at higher doses, so combined effects on the heart and CNS are possible.
How serious is the interaction between Promethazine and Venlafaxine?
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 sedation and palpitations, and obtain an ECG if other QT risk factors are present.
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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