Drug interactions
Erythromycin + Moxifloxacin
Severity: Major
Erythromycin and Moxifloxacin: major interaction.
Last updated Sources: UK SmPC
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 antibiotics prolong the QT interval, and combined use increases the risk of torsades de pointes. The risk is higher with hypokalemia, bradycardia or structural heart disease.
What this interaction means in plain words
Erythromycin and Moxifloxacin 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.
Erythromycin belongs to Anti Bacterial; Moxifloxacin belongs to Anti Bacterial.
Why it happens
Additive blockade of cardiac potassium channels (hERG), delaying repolarization.
What to do
Avoid the combination and choose an antibiotic regimen without both QT-prolonging agents. If unavoidable, monitor ECG and correct electrolytes.
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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References
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 Moxifloxacin
- Amiodarone + Moxifloxacin Contraindicated
- Arsenic trioxide + Moxifloxacin Contraindicated
- Disopyramide + Moxifloxacin Contraindicated
- Dofetilide + Moxifloxacin Contraindicated
- Dronedarone + Moxifloxacin Contraindicated
- Droperidol + Moxifloxacin Contraindicated
Frequently asked questions
Can I take Erythromycin with Moxifloxacin?
MediHelp rates the interaction as major. Erythromycin and Moxifloxacin 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. Both antibiotics prolong the QT interval, and combined use increases the risk of torsades de pointes. The risk is higher with hypokalemia, bradycardia or structural heart disease.
How serious is the interaction between Erythromycin and Moxifloxacin?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid the combination and choose an antibiotic regimen without both QT-prolonging agents. If unavoidable, monitor ECG and correct electrolytes.
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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