Drug interactions
Ondansetron + Protriptyline
Severity: Major
Ondansetron and Protriptyline: major 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
Protriptyline, a tricyclic antidepressant, can prolong the QT interval and ondansetron adds to this effect. Both agents also have serotonergic activity, so serotonin toxicity is a theoretical concern, although it is rarely reported.
What this interaction means in plain words
Ondansetron and Protriptyline can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Why it happens
Additive QT prolongation, plus a possible additive serotonergic effect.
What to do
Use an alternative antiemetic when feasible. If combined, obtain an ECG, correct electrolytes and watch for serotonin toxicity symptoms such as agitation, tremor and hyperthermia.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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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
Frequently asked questions
Can I take Ondansetron with Protriptyline?
MediHelp rates the interaction as major. Ondansetron and Protriptyline can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Protriptyline, a tricyclic antidepressant, can prolong the QT interval and ondansetron adds to this effect. Both agents also have serotonergic activity, so serotonin toxicity is a theoretical concern, although it is rarely reported.
How serious is the interaction between Ondansetron and Protriptyline?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Use an alternative antiemetic when feasible. If combined, obtain an ECG, correct electrolytes and watch for serotonin toxicity symptoms such as agitation, tremor and hyperthermia.
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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