Drug interactions
Flecainide + Foscarnet
Severity: Major
Flecainide and Foscarnet: 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
Flecainide slows cardiac conduction and can be proarrhythmic, and foscarnet can prolong QT and cause electrolyte disturbances. The combination raises the risk of serious ventricular arrhythmia.
What this interaction means in plain words
Flecainide and Foscarnet 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.
Flecainide belongs to Cardiovascular; Foscarnet belongs to Anti Virals.
Why it happens
Additive effects on cardiac conduction and repolarization, aggravated by electrolyte disturbance.
What to do
Avoid if possible; otherwise monitor ECG and keep potassium, magnesium and calcium within normal ranges. Consider flecainide plasma levels and dose reduction if conduction intervals lengthen.
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 Foscarnet
- Cidofovir + Foscarnet Contraindicated
- Foscarnet + Pimozide Contraindicated
- Foscarnet + Thioridazine Contraindicated
- Foscarnet + Vandetanib Contraindicated
- Adagrasib + Foscarnet Major
- Adefovir + Foscarnet Major
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 Foscarnet?
MediHelp rates the interaction as major. Flecainide and Foscarnet 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. Flecainide slows cardiac conduction and can be proarrhythmic, and foscarnet can prolong QT and cause electrolyte disturbances. The combination raises the risk of serious ventricular arrhythmia.
How serious is the interaction between Flecainide and Foscarnet?
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 if possible; otherwise monitor ECG and keep potassium, magnesium and calcium within normal ranges. Consider flecainide plasma levels and dose reduction if conduction intervals lengthen.
What other medicines interact with Foscarnet?
MediHelp also lists interactions of Foscarnet with, for example, Cidofovir, Pimozide, Thioridazine. The full list is on the Foscarnet page.
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