Phenobarbital and Quetiapine: Drug Interaction Guide
Quick answer: This is a major interaction — avoid combining Phenobarbital and Quetiapine unless specifically directed by your doctor.
How Phenobarbital interacts with Quetiapine
Phenobarbital strongly induces CYP3A4, dramatically reducing quetiapine plasma concentrations and therapeutic effect.
What you should do
Consider an alternative antipsychotic metabolised via other pathways (e.g., olanzapine, paliperidone); if combination needed, quetiapine doses up to 5-fold higher than usual may be required.
Key facts
Severity
Major — avoid combination
Mechanism
Phenobarbital strongly induces CYP3A4, dramatically reducing quetiapine plasma concentrations and therapeutic effect.
Action
Consider an alternative antipsychotic metabolised via other pathways (e.g., olanzapine, paliperidone); if combination ne...
Frequently asked questions
Can I take Phenobarbital and Quetiapine together?
No — this combination should generally be avoided. Consider an alternative antipsychotic metabolised via other pathways (e.g., olanzapine, paliperidone); if combination needed, quetiapine doses up to 5-fold higher than usual may be required.
What is the severity of this interaction?
The interaction between Phenobarbital and Quetiapine is classified as Major — avoid combination. Phenobarbital strongly induces CYP3A4, dramatically reducing quetiapine plasma concentrations and therapeutic effect.
What should I do if I'm prescribed both?
Consider an alternative antipsychotic metabolised via other pathways (e.g., olanzapine, paliperidone); if combination needed, quetiapine doses up to 5-fold higher than usual may be required. Always consult your prescribing clinician — do not stop or change medications without medical guidance.
Last reviewed: by iMedic Medical Editorial Team. Our editorial process.