Drug interactions
Moxifloxacin + Phenytoin
Severity: Moderate
Moxifloxacin 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
Quinolones have been reported to change phenytoin concentrations, in either direction, in isolated cases. Loss of seizure control or phenytoin toxicity could result, and quinolones may also lower the seizure threshold.
What this interaction means in plain words
Moxifloxacin 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.
Moxifloxacin belongs to Anti Bacterial; Phenytoin belongs to Central Nervous System.
Why it happens
The mechanism is not well established; variable effects on phenytoin concentrations have been reported.
What to do
Monitor phenytoin levels and seizure control when starting or stopping moxifloxacin, and adjust the phenytoin dose accordingly.
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 Moxifloxacin
- Amiodarone + Moxifloxacin Contraindicated
- Arsenic trioxide + Moxifloxacin Contraindicated
- Disopyramide + Moxifloxacin Contraindicated
- Dofetilide + Moxifloxacin Contraindicated
- Dronedarone + Moxifloxacin Contraindicated
- Droperidol + Moxifloxacin Contraindicated
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 Moxifloxacin with Phenytoin?
MediHelp rates the interaction as moderate. Moxifloxacin 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. Quinolones have been reported to change phenytoin concentrations, in either direction, in isolated cases. Loss of seizure control or phenytoin toxicity could result, and quinolones may also lower the seizure threshold.
How serious is the interaction between Moxifloxacin 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 control when starting or stopping moxifloxacin, and adjust the phenytoin dose accordingly.
What other medicines interact with Moxifloxacin?
MediHelp also lists interactions of Moxifloxacin with, for example, Amiodarone, Arsenic trioxide, Disopyramide. The full list is on the Moxifloxacin page.
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