Drug interactions
Levodopa + Phenytoin
Severity: Moderate
Levodopa 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
Phenytoin has been reported to reduce the antiparkinsonian effect of levodopa, with worsening of motor symptoms. Reports are limited.
What this interaction means in plain words
Levodopa 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.
Levodopa belongs to Central Nervous System; Phenytoin belongs to Central Nervous System.
Why it happens
Mechanism is not established; possible pharmacodynamic antagonism.
What to do
Monitor parkinsonian symptoms and increase the levodopa dose if needed. Consider an alternative anticonvulsant if control is lost.
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
Other interactions of Levodopa
- Isocarboxazid + Levodopa Contraindicated
- Levodopa + Phenelzine Contraindicated
- Levodopa + Phenelzine (nonselective MAOI) Contraindicated
- Levodopa + Procarbazine Contraindicated
- Levodopa + Tranylcypromine Contraindicated
- Amisulpride + Levodopa Major
Frequently asked questions
Can I take Levodopa with Phenytoin?
MediHelp rates the interaction as moderate. Levodopa 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. Phenytoin has been reported to reduce the antiparkinsonian effect of levodopa, with worsening of motor symptoms. Reports are limited.
How serious is the interaction between Levodopa 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 parkinsonian symptoms and increase the levodopa dose if needed. Consider an alternative anticonvulsant if control is lost.
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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