Drug interactions
Mexiletine + Terbinafine
Severity: Moderate
Mexiletine and Terbinafine: 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
Mexiletine is a CYP1A2 substrate and weak inhibitor, and a significant effect on terbinafine is unlikely. Conversely, terbinafine inhibits CYP2D6, which contributes to mexiletine metabolism and may raise mexiletine levels, which matters because mexiletine has a narrow therapeutic index.
What this interaction means in plain words
Mexiletine and Terbinafine 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.
Mexiletine belongs to Cardiovascular; Terbinafine belongs to Anti Fungals.
Why it happens
Terbinafine inhibits CYP2D6, reducing mexiletine metabolism; the effect of mexiletine on terbinafine is minimal.
What to do
Monitor for mexiletine toxicity such as tremor, dizziness, nausea and arrhythmia, and consider a mexiletine dose reduction.
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 Terbinafine
- Terbinafine + Thioridazine Contraindicated
- Desipramine + Terbinafine Major
- Eliglustat + Terbinafine Major
- Flecainide + Terbinafine Major
- Imipramine + Terbinafine Major
- Maprotiline + Terbinafine Major
Other interactions of Mexiletine
- Fezolinetant + Mexiletine Contraindicated
- Mexiletine + Pimozide Contraindicated
- Alosetron + Mexiletine Major
- Amiodarone + Mexiletine Major
- Clozapine + Mexiletine Major
- Cobicistat + Mexiletine Major
Frequently asked questions
Can I take Mexiletine with Terbinafine?
MediHelp rates the interaction as moderate. Mexiletine and Terbinafine 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. Mexiletine is a CYP1A2 substrate and weak inhibitor, and a significant effect on terbinafine is unlikely. Conversely, terbinafine inhibits CYP2D6, which contributes to mexiletine metabolism and may raise mexiletine levels, which matters because mexiletine has a narrow therapeutic index.
How serious is the interaction between Mexiletine and Terbinafine?
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 for mexiletine toxicity such as tremor, dizziness, nausea and arrhythmia, and consider a mexiletine dose reduction.
What other medicines interact with Terbinafine?
MediHelp also lists interactions of Terbinafine with, for example, Thioridazine, Desipramine, Eliglustat. The full list is on the Terbinafine page.
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