Drug interactions
Formoterol + Ondansetron
Severity: Moderate
Formoterol 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
Ondansetron causes dose-dependent QT prolongation, especially with intravenous dosing. Formoterol may add to the effect and lower potassium, increasing the risk of torsades de pointes in susceptible patients.
What this interaction means in plain words
Formoterol 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.
Formoterol belongs to Respiratory; Ondansetron belongs to Gastrointestinal Tract.
Why it happens
Additive QT prolongation, with beta-2 agonist hypokalemia contributing.
What to do
Avoid in congenital long QT syndrome; otherwise check ECG and electrolytes in patients with cardiac risk factors. Use the lowest effective ondansetron dose or an alternative 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?
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Other interactions of Formoterol
- Adagrasib + Formoterol Major
- Amiodarone + Formoterol Major
- Amisulpride + Formoterol Major
- Amitriptyline + Formoterol Major
- Amoxapine + Formoterol Major
- Arformoterol + Formoterol Major
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 Formoterol with Ondansetron?
MediHelp rates the interaction as moderate. Formoterol 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. Ondansetron causes dose-dependent QT prolongation, especially with intravenous dosing. Formoterol may add to the effect and lower potassium, increasing the risk of torsades de pointes in susceptible patients.
How serious is the interaction between Formoterol 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; otherwise check ECG and electrolytes in patients with cardiac risk factors. Use the lowest effective ondansetron dose or an alternative antiemetic if QTc is prolonged.
What other medicines interact with Formoterol?
MediHelp also lists interactions of Formoterol with, for example, Adagrasib, Amiodarone, Amisulpride. The full list is on the Formoterol page.
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