Drug interactions
Olanzapine + Venlafaxine
Severity: Moderate
Olanzapine 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 and olanzapine are often combined, but the pairing can rarely cause serotonin syndrome or neuroleptic malignant syndrome. Both drugs have minor effects on QT, and additive sedation, orthostatic hypotension and metabolic effects can occur.
What this interaction means in plain words
Olanzapine 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.
Olanzapine belongs to Central Nervous System; Venlafaxine belongs to Central Nervous System.
Why it happens
Additive serotonergic, dopamine-blocking and mild QT-prolonging pharmacodynamic effects.
What to do
Monitor for signs of serotonin toxicity, neuroleptic malignant syndrome, sedation and blood pressure changes. Check an ECG if other QT-prolonging 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 Venlafaxine
- Isocarboxazid + Venlafaxine Contraindicated
- Methylene blue + Venlafaxine Contraindicated
- Phenelzine + Venlafaxine Contraindicated
- Procarbazine + Venlafaxine Contraindicated
- Rasagiline + Venlafaxine Contraindicated
- Safinamide + Venlafaxine Contraindicated
Other interactions of Olanzapine
Frequently asked questions
Can I take Olanzapine with Venlafaxine?
MediHelp rates the interaction as moderate. Olanzapine 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 and olanzapine are often combined, but the pairing can rarely cause serotonin syndrome or neuroleptic malignant syndrome. Both drugs have minor effects on QT, and additive sedation, orthostatic hypotension and metabolic effects can occur.
How serious is the interaction between Olanzapine 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 signs of serotonin toxicity, neuroleptic malignant syndrome, sedation and blood pressure changes. Check an ECG if other QT-prolonging risk factors are present.
What other medicines interact with Venlafaxine?
MediHelp also lists interactions of Venlafaxine with, for example, Isocarboxazid, Methylene blue, Phenelzine. The full list is on the Venlafaxine page.
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