Drug interactions
Ondansetron + Venlafaxine
Severity: Moderate
Ondansetron 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
Serotonin syndrome has been reported with ondansetron given alongside serotonergic antidepressants such as venlafaxine. Venlafaxine may also prolong the QT interval slightly, which adds to the ondansetron effect.
What this interaction means in plain words
Ondansetron 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.
Ondansetron belongs to Gastrointestinal Tract; Venlafaxine belongs to Central Nervous System.
Why it happens
Possible additive serotonergic activity together with additive QT prolongation.
What to do
The combination is usually workable; monitor for serotonin toxicity such as tremor, clonus, hyperthermia and agitation, and check an ECG in patients with cardiac risk factors. Stop the serotonergic drugs if toxicity appears.
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 Ondansetron
- Apomorphine + Ondansetron Contraindicated
- Ondansetron + Thioridazine Contraindicated
- Ondansetron + Vandetanib Contraindicated
- Adagrasib + Ondansetron Major
- Amiodarone + Ondansetron Major
- Amisulpride + Ondansetron 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 Ondansetron with Venlafaxine?
MediHelp rates the interaction as moderate. Ondansetron 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. Serotonin syndrome has been reported with ondansetron given alongside serotonergic antidepressants such as venlafaxine. Venlafaxine may also prolong the QT interval slightly, which adds to the ondansetron effect.
How serious is the interaction between Ondansetron 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: The combination is usually workable; monitor for serotonin toxicity such as tremor, clonus, hyperthermia and agitation, and check an ECG in patients with cardiac risk factors. Stop the serotonergic drugs if toxicity appears.
What other medicines interact with Ondansetron?
MediHelp also lists interactions of Ondansetron with, for example, Apomorphine, Thioridazine, Vandetanib. The full list is on the Ondansetron page.
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