Drug interactions
Methylphenidate + Phenytoin
Severity: Moderate
Methylphenidate 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
Case reports suggest methylphenidate may raise phenytoin concentrations, possibly causing nystagmus, ataxia or other toxicity. The effect is inconsistent and the mechanism is uncertain.
What this interaction means in plain words
Methylphenidate 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.
Methylphenidate belongs to Central Nervous System; Phenytoin belongs to Central Nervous System.
Why it happens
Possible inhibition of phenytoin metabolism; not firmly established.
What to do
Check phenytoin levels and watch for toxicity when methylphenidate is started or increased, and recheck if it is stopped.
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 Methylphenidate
- Isocarboxazid + Methylphenidate Contraindicated
- Linezolid + Methylphenidate Contraindicated
- Methylphenidate + Phenelzine Contraindicated
- Methylphenidate + Procarbazine Contraindicated
- Methylphenidate + Rasagiline Contraindicated
- Methylphenidate + Safinamide 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 Methylphenidate with Phenytoin?
MediHelp rates the interaction as moderate. Methylphenidate 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. Case reports suggest methylphenidate may raise phenytoin concentrations, possibly causing nystagmus, ataxia or other toxicity. The effect is inconsistent and the mechanism is uncertain.
How serious is the interaction between Methylphenidate 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: Check phenytoin levels and watch for toxicity when methylphenidate is started or increased, and recheck if it is stopped.
What other medicines interact with Methylphenidate?
MediHelp also lists interactions of Methylphenidate with, for example, Isocarboxazid, Linezolid, Phenelzine. The full list is on the Methylphenidate page.
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