Drug interactions
Phenobarbital + Terbinafine
Severity: Moderate
Phenobarbital 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
Phenobarbital is a broad CYP inducer and may lower terbinafine concentrations by accelerating its metabolism. Reduced exposure may cause antifungal treatment failure.
What this interaction means in plain words
Phenobarbital 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.
Why it happens
Phenobarbital induces CYP1A2, CYP2C9 and CYP3A4, increasing terbinafine clearance.
What to do
Monitor for lack of antifungal response and consider a longer course, higher-intensity regimen or alternative antifungal if response is inadequate.
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
Frequently asked questions
Can I take Phenobarbital with Terbinafine?
MediHelp rates the interaction as moderate. Phenobarbital 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. Phenobarbital is a broad CYP inducer and may lower terbinafine concentrations by accelerating its metabolism. Reduced exposure may cause antifungal treatment failure.
How serious is the interaction between Phenobarbital 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 lack of antifungal response and consider a longer course, higher-intensity regimen or alternative antifungal if response is inadequate.
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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