Drug interactions
Flecainide + Procainamide
Severity: Major
Flecainide and Procainamide: 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 are sodium channel blocking antiarrhythmics that slow conduction and can prolong QRS and QT intervals. Combined use raises the risk of severe bradyarrhythmia, conduction block and ventricular proarrhythmia, with no clear therapeutic benefit.
What this interaction means in plain words
Flecainide and Procainamide 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.
Why it happens
Additive sodium channel blockade and effects on cardiac repolarization.
What to do
Avoid concurrent use of these two class I agents. If a switch is needed, allow adequate washout and monitor ECG.
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 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 Flecainide with Procainamide?
MediHelp rates the interaction as major. Flecainide and Procainamide 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 are sodium channel blocking antiarrhythmics that slow conduction and can prolong QRS and QT intervals. Combined use raises the risk of severe bradyarrhythmia, conduction block and ventricular proarrhythmia, with no clear therapeutic benefit.
How serious is the interaction between Flecainide and Procainamide?
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 concurrent use of these two class I agents. If a switch is needed, allow adequate washout and monitor ECG.
What other medicines interact with Flecainide?
MediHelp also lists interactions of Flecainide with, for example, Nirmatrelvir, Nirmatrelvir / ritonavir, Pimozide. The full list is on the Flecainide page.
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