Drug interactions
Phenobarbital + Risperidone
Severity: Moderate
Phenobarbital and Risperidone: 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 can lower risperidone and active metabolite concentrations through enzyme and transporter induction, potentially reducing antipsychotic effect. Both drugs also cause sedation, so additive CNS depression is likely.
What this interaction means in plain words
Phenobarbital and Risperidone 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
Induction of CYP3A4 and P-glycoprotein by phenobarbital, plus additive CNS depression.
What to do
Monitor clinical response and sedation, and consider increasing the risperidone dose if efficacy is lost. Reduce the dose again if the barbiturate is withdrawn.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 Risperidone
- Ibutilide + Risperidone Contraindicated
- Risperidone + Vandetanib Contraindicated
- Adagrasib + Risperidone Major
- Amiodarone + Risperidone Major
- Amisulpride + Risperidone Major
- Amoxapine + Risperidone Major
Frequently asked questions
Can I take Phenobarbital with Risperidone?
MediHelp rates the interaction as moderate. Phenobarbital and Risperidone 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 can lower risperidone and active metabolite concentrations through enzyme and transporter induction, potentially reducing antipsychotic effect. Both drugs also cause sedation, so additive CNS depression is likely.
How serious is the interaction between Phenobarbital and Risperidone?
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 clinical response and sedation, and consider increasing the risperidone dose if efficacy is lost. Reduce the dose again if the barbiturate is withdrawn.
What other medicines interact with Risperidone?
MediHelp also lists interactions of Risperidone with, for example, Ibutilide, Vandetanib, Adagrasib. The full list is on the Risperidone page.
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