Drug interactions
Amitriptyline + Ondansetron
Severity: Moderate
Amitriptyline and Ondansetron: 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
Amitriptyline can prolong the QT interval and has serotonergic activity, and ondansetron adds to both effects. This raises the risk of arrhythmia and, rarely, serotonin syndrome.
What this interaction means in plain words
Amitriptyline and Ondansetron 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.
Amitriptyline belongs to Central Nervous System; Ondansetron belongs to Gastrointestinal Tract.
Why it happens
Additive QT prolongation plus possible additive serotonergic effects.
What to do
Avoid in congenital long QT syndrome and correct electrolytes. Monitor the ECG in high-risk patients and watch for serotonin toxicity.
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 Amitriptyline
- Amitriptyline + Isocarboxazid Contraindicated
- Amitriptyline + Methylene blue Contraindicated
- Amitriptyline + Phenelzine Contraindicated
- Amitriptyline + Pimozide Contraindicated
- Amitriptyline + Procarbazine Contraindicated
- Amitriptyline + Safinamide Contraindicated
Frequently asked questions
Can I take Amitriptyline with Ondansetron?
MediHelp rates the interaction as moderate. Amitriptyline and Ondansetron 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. Amitriptyline can prolong the QT interval and has serotonergic activity, and ondansetron adds to both effects. This raises the risk of arrhythmia and, rarely, serotonin syndrome.
How serious is the interaction between Amitriptyline and Ondansetron?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid in congenital long QT syndrome and correct electrolytes. Monitor the ECG in high-risk patients and watch for serotonin toxicity.
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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