Drug interactions
Flecainide + Lily of the valley
Severity: Moderate
Flecainide and Lily of the valley: 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
Lily of the valley contains cardiac glycosides such as convallatoxin that affect cardiac conduction and rhythm. With flecainide, the risk of conduction disturbances and arrhythmia may increase.
What this interaction means in plain words
Flecainide and Lily of the valley 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.
Why it happens
Additive pharmacodynamic effects on cardiac conduction from glycoside activity and sodium channel blockade.
What to do
Advise patients to avoid herbal products containing lily of the valley. If exposure occurs, obtain an ECG and check 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 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 Lily of the valley?
MediHelp rates the interaction as moderate. Flecainide and Lily of the valley 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. Lily of the valley contains cardiac glycosides such as convallatoxin that affect cardiac conduction and rhythm. With flecainide, the risk of conduction disturbances and arrhythmia may increase.
How serious is the interaction between Flecainide and Lily of the valley?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Advise patients to avoid herbal products containing lily of the valley. If exposure occurs, obtain an ECG and check potassium.
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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