Drug interactions
Fluphenazine + Ondansetron
Severity: Moderate
Fluphenazine 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
Both drugs can prolong the QT interval, so giving them together may raise the risk of torsades de pointes, particularly with electrolyte disturbances, heart failure, bradycardia or congenital long QT syndrome. The risk is greater with intravenous ondansetron or higher doses.
What this interaction means in plain words
Fluphenazine 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.
Fluphenazine belongs to Central Nervous System; Ondansetron belongs to Gastrointestinal Tract.
Why it happens
Additive blockade of cardiac hERG potassium channels causing delayed ventricular repolarization.
What to do
Obtain a baseline ECG and correct potassium and magnesium before combining. Avoid in congenital long QT syndrome and consider a non-QT-prolonging antiemetic if QTc is prolonged.
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?
Pro+ members
Unlock the full page
Create an account and start a Pro+ trial to unlock the full management advice for Fluphenazine and Ondansetron, the additional notes, the evidence detail and the whole-prescription interaction checker.
- Full clinical management advice
- Additional notes
- Evidence detail
- Interaction checker for a whole prescription
Try Pro+ free for 7 days on the web. No card needed.
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 Fluphenazine
- Arsenic trioxide + Fluphenazine Contraindicated
- Dofetilide + Fluphenazine Contraindicated
- Fluphenazine + Ibutilide Contraindicated
- Fluphenazine + Pimozide Contraindicated
- Adagrasib + Fluphenazine Major
- Alfentanil + Fluphenazine Major
Frequently asked questions
Can I take Fluphenazine with Ondansetron?
MediHelp rates the interaction as moderate. Fluphenazine 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. Both drugs can prolong the QT interval, so giving them together may raise the risk of torsades de pointes, particularly with electrolyte disturbances, heart failure, bradycardia or congenital long QT syndrome. The risk is greater with intravenous ondansetron or higher doses.
How serious is the interaction between Fluphenazine 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: Obtain a baseline ECG and correct potassium and magnesium before combining. Avoid in congenital long QT syndrome and consider a non-QT-prolonging antiemetic if QTc is prolonged.
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.
Full monographs, dosing and an interaction checker in the MediHelp app
Open the complete reference, check multi-drug interactions and use dosing tools in the MediHelp app.
