Drug interactions
Erythromycin + Formoterol
Severity: Moderate
Erythromycin 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 potassium, and erythromycin also prolongs QT. Together they may increase the risk of ventricular arrhythmias, mainly with high doses of formoterol.
What this interaction means in plain words
Erythromycin 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.
Erythromycin belongs to Anti Bacterial; Formoterol belongs to Respiratory.
Why it happens
Additive QT prolongation with beta-agonist induced hypokalemia.
What to do
Use usual inhaled doses and monitor for palpitations. In patients with other QT risk factors, check ECG and potassium.
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 Erythromycin
- Conivaptan + Erythromycin Contraindicated
- Dihydroergotamine intranasal + Erythromycin Contraindicated
- Dihydroergotamine + Erythromycin Contraindicated
- Domperidone + Erythromycin Contraindicated
- Dronedarone + Erythromycin Contraindicated
- Droperidol + Erythromycin Contraindicated
Other interactions of Formoterol
- Adagrasib + Formoterol Major
- Amiodarone + Formoterol Major
- Amisulpride + Formoterol Major
- Amitriptyline + Formoterol Major
- Amoxapine + Formoterol Major
- Arformoterol + Formoterol Major
Frequently asked questions
Can I take Erythromycin with Formoterol?
MediHelp rates the interaction as moderate. Erythromycin 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 potassium, and erythromycin also prolongs QT. Together they may increase the risk of ventricular arrhythmias, mainly with high doses of formoterol.
How serious is the interaction between Erythromycin 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: Use usual inhaled doses and monitor for palpitations. In patients with other QT risk factors, check ECG and potassium.
What other medicines interact with Erythromycin?
MediHelp also lists interactions of Erythromycin with, for example, Conivaptan, Dihydroergotamine intranasal, Dihydroergotamine. The full list is on the Erythromycin page.
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