Drug interactions
Levofloxacin + Phenytoin
Severity: Moderate
Levofloxacin 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
Fluoroquinolones have been reported to change phenytoin concentrations, with both reductions and increases described, which can lead to loss of seizure control or toxicity. Fluoroquinolones also lower the seizure threshold on their own.
What this interaction means in plain words
Levofloxacin 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.
Levofloxacin belongs to Anti Bacterial; Phenytoin belongs to Central Nervous System.
Why it happens
The pharmacokinetic mechanism is not established; additive lowering of seizure threshold is a pharmacodynamic concern.
What to do
Monitor phenytoin levels and seizure activity when levofloxacin is started or stopped. Adjust the phenytoin dose as indicated.
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 Levofloxacin
- Dronedarone + Levofloxacin Contraindicated
- Ibutilide + Levofloxacin Contraindicated
- Levofloxacin + Thioridazine Contraindicated
- Levofloxacin + Vandetanib Contraindicated
- Levofloxacin + Ziprasidone Contraindicated
- Adagrasib + Levofloxacin Major
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 Levofloxacin with Phenytoin?
MediHelp rates the interaction as moderate. Levofloxacin 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. Fluoroquinolones have been reported to change phenytoin concentrations, with both reductions and increases described, which can lead to loss of seizure control or toxicity. Fluoroquinolones also lower the seizure threshold on their own.
How serious is the interaction between Levofloxacin 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: Monitor phenytoin levels and seizure activity when levofloxacin is started or stopped. Adjust the phenytoin dose as indicated.
What other medicines interact with Levofloxacin?
MediHelp also lists interactions of Levofloxacin with, for example, Dronedarone, Ibutilide, Thioridazine. The full list is on the Levofloxacin page.
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