Phenobarbital and Voriconazole: Drug Interaction Guide
Quick answer: This is a major interaction — avoid combining Phenobarbital and Voriconazole unless specifically directed by your doctor.
How Phenobarbital interacts with Voriconazole
Phenobarbital strongly induces CYP enzymes including CYP2C19, CYP2C9, and CYP3A4, which metabolize voriconazole. Voriconazole exposure may fall substantially, risking antifungal failure.
What you should do
Avoid the combination and use an alternative antifungal or anticonvulsant. If no alternative exists, specialist therapeutic drug monitoring is required.
Key facts
Severity
Major — avoid combination
Mechanism
Phenobarbital strongly induces CYP enzymes including CYP2C19, CYP2C9, and CYP3A4, which metabolize voriconazole. Voricon...
Action
Avoid the combination and use an alternative antifungal or anticonvulsant. If no alternative exists, specialist therapeu...
Frequently asked questions
Can I take Phenobarbital and Voriconazole together?
No — this combination should generally be avoided. Avoid the combination and use an alternative antifungal or anticonvulsant. If no alternative exists, specialist therapeutic drug monitoring is required.
What is the severity of this interaction?
The interaction between Phenobarbital and Voriconazole is classified as Major — avoid combination. Phenobarbital strongly induces CYP enzymes including CYP2C19, CYP2C9, and CYP3A4, which metabolize voriconazole. Voriconazole exposure may fall substantially, risking antifungal failure.
What should I do if I'm prescribed both?
Avoid the combination and use an alternative antifungal or anticonvulsant. If no alternative exists, specialist therapeutic drug monitoring is 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.