Drug interactions
Lily of the valley + Phenytoin
Severity: Moderate
Lily of the valley and Phenytoin: 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 that can cause arrhythmias and conduction disturbances. Phenytoin also affects cardiac conduction, so combined use could theoretically add to rhythm disturbances, though documentation is minimal.
What this interaction means in plain words
Lily of the valley and Phenytoin 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
Possible additive effects on cardiac conduction from cardiac glycoside content and phenytoin; not well characterized.
What to do
Avoid use of lily of the valley preparations in patients on phenytoin, and obtain an ECG if exposure has occurred.
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 Phenytoin
- Artemether / lumefantrine + Phenytoin Contraindicated
- Bictegravir + Phenytoin Contraindicated
- Cabotegravir + Phenytoin Contraindicated
- Doravirine + Phenytoin Contraindicated
- Elbasvir / grazoprevir + Phenytoin Contraindicated
- Elvitegravir / cobicistat / emtricitabine / tenofovir df + Phenytoin Contraindicated
Frequently asked questions
Can I take Lily of the valley with Phenytoin?
MediHelp rates the interaction as moderate. Lily of the valley and Phenytoin 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 that can cause arrhythmias and conduction disturbances. Phenytoin also affects cardiac conduction, so combined use could theoretically add to rhythm disturbances, though documentation is minimal.
How serious is the interaction between Lily of the valley and Phenytoin?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid use of lily of the valley preparations in patients on phenytoin, and obtain an ECG if exposure has occurred.
What other medicines interact with Phenytoin?
MediHelp also lists interactions of Phenytoin with, for example, Artemether / lumefantrine, Bictegravir, Cabotegravir. The full list is on the Phenytoin page.
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