Drug interactions
Clarithromycin + Flecainide
Severity: Major
Clarithromycin and Flecainide: major 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 cardiac conduction and repolarization, and combining them raises the risk of ventricular arrhythmias including torsades de pointes. Flecainide also has proarrhythmic potential in structural heart disease, and clarithromycin may add to exposure via CYP inhibition.
What this interaction means in plain words
Clarithromycin and Flecainide 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.
Clarithromycin belongs to Anti Bacterial; Flecainide belongs to Cardiovascular.
Why it happens
Additive effects on cardiac conduction and QT interval, with possible clarithromycin inhibition of CYP-mediated flecainide clearance.
What to do
Avoid the combination where possible and use an alternative antibiotic such as azithromycin or a non-macrolide; if used, obtain a baseline ECG, correct potassium and magnesium, and monitor QTc and QRS.
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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Other interactions of Clarithromycin
- Astemizole + Clarithromycin Contraindicated
- Avanafil + Clarithromycin Contraindicated
- Cisapride + Clarithromycin Contraindicated
- Clarithromycin + Colchicine Contraindicated
- Clarithromycin + Conivaptan Contraindicated
- Clarithromycin + Dihydroergotamine Contraindicated
Other interactions of Flecainide
- Flecainide + Nirmatrelvir Contraindicated
- Flecainide + Nirmatrelvir / ritonavir Contraindicated
- Flecainide + Pimozide Contraindicated
- Flecainide + Ritonavir Contraindicated
- Flecainide + Thioridazine Contraindicated
- Flecainide + Tipranavir Contraindicated
Frequently asked questions
Can I take Clarithromycin with Flecainide?
MediHelp rates the interaction as major. Clarithromycin and Flecainide 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 drugs can prolong cardiac conduction and repolarization, and combining them raises the risk of ventricular arrhythmias including torsades de pointes. Flecainide also has proarrhythmic potential in structural heart disease, and clarithromycin may add to exposure via CYP inhibition.
How serious is the interaction between Clarithromycin and Flecainide?
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 where possible and use an alternative antibiotic such as azithromycin or a non-macrolide; if used, obtain a baseline ECG, correct potassium and magnesium, and monitor QTc and QRS.
What other medicines interact with Clarithromycin?
MediHelp also lists interactions of Clarithromycin with, for example, Astemizole, Avanafil, Cisapride. The full list is on the Clarithromycin page.
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