Drug interactions
Modafinil + Phenobarbital
Severity: Moderate
Modafinil 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 is a potent enzyme inducer and can lower modafinil concentrations, reducing its effect. Additive CNS effects are also possible.
What this interaction means in plain words
Modafinil 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 CYP3A4 and other enzymes, increasing modafinil clearance.
What to do
Monitor for reduced modafinil efficacy and increase the dose if needed. Reduce the modafinil dose after phenobarbital 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 Modafinil
Frequently asked questions
Can I take Modafinil with Phenobarbital?
MediHelp rates the interaction as moderate. Modafinil 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 is a potent enzyme inducer and can lower modafinil concentrations, reducing its effect. Additive CNS effects are also possible.
How serious is the interaction between Modafinil 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: Monitor for reduced modafinil efficacy and increase the dose if needed. Reduce the modafinil dose after phenobarbital is stopped.
What other medicines interact with Modafinil?
MediHelp also lists interactions of Modafinil with, for example, Lenacapavir, Leniolisib, Lorlatinib. The full list is on the Modafinil page.
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