Drug interactions
Fluconazole + Formoterol
Severity: Moderate
Fluconazole and Formoterol: 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
Formoterol can prolong the QT interval and lower serum potassium, and fluconazole is also associated with QT prolongation and torsades de pointes. Used together, the risk of a serious ventricular arrhythmia may increase, particularly with high doses, electrolyte disturbance or underlying heart disease.
What this interaction means in plain words
Fluconazole and Formoterol 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.
Fluconazole belongs to Anti Fungals; Formoterol belongs to Respiratory.
Why it happens
Additive pharmacodynamic QT prolongation, with beta-2 agonist induced hypokalemia adding to the arrhythmic risk.
What to do
Check potassium and magnesium and correct deficits; obtain a baseline ECG in patients with cardiac risk factors. Use standard inhaled formoterol doses and consider an alternative antifungal if QTc lengthens.
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 Fluconazole
- Dihydroergotamine intranasal + Fluconazole Contraindicated
- Dihydroergotamine + Fluconazole Contraindicated
- Dofetilide + Fluconazole Contraindicated
- Domperidone + Fluconazole Contraindicated
- Dronedarone + Fluconazole Contraindicated
- Erythromycin + Fluconazole Contraindicated
Frequently asked questions
Can I take Fluconazole with Formoterol?
MediHelp rates the interaction as moderate. Fluconazole and Formoterol 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 can prolong the QT interval and lower serum potassium, and fluconazole is also associated with QT prolongation and torsades de pointes. Used together, the risk of a serious ventricular arrhythmia may increase, particularly with high doses, electrolyte disturbance or underlying heart disease.
How serious is the interaction between Fluconazole and Formoterol?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Check potassium and magnesium and correct deficits; obtain a baseline ECG in patients with cardiac risk factors. Use standard inhaled formoterol doses and consider an alternative antifungal if QTc lengthens.
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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