Drug interactions
Lamotrigine + Phenobarbital
Severity: Moderate
Lamotrigine and Phenobarbital: 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 reduces lamotrigine concentrations, which may lead to breakthrough seizures. Stopping phenobarbital can cause lamotrigine levels to rise.
What this interaction means in plain words
Lamotrigine and Phenobarbital 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 UDP-glucuronosyltransferase and increases lamotrigine clearance.
What to do
Use the higher lamotrigine titration regimen recommended with enzyme inducers and monitor seizure control. Reduce lamotrigine if phenobarbital is withdrawn.
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 Lamotrigine
Frequently asked questions
Can I take Lamotrigine with Phenobarbital?
MediHelp rates the interaction as moderate. Lamotrigine and Phenobarbital 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 reduces lamotrigine concentrations, which may lead to breakthrough seizures. Stopping phenobarbital can cause lamotrigine levels to rise.
How serious is the interaction between Lamotrigine and Phenobarbital?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Use the higher lamotrigine titration regimen recommended with enzyme inducers and monitor seizure control. Reduce lamotrigine if phenobarbital is withdrawn.
What other medicines interact with Lamotrigine?
MediHelp also lists interactions of Lamotrigine with, for example, Desogestrel-ethinyl estradiol, Divalproex, Dofetilide. The full list is on the Lamotrigine page.
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