Drug interactions
Phenobarbital + Tacrolimus
Severity: Major
Phenobarbital and Tacrolimus: major 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 strongly induces metabolism and can substantially lower tacrolimus levels, risking rejection.
What this interaction means in plain words
Phenobarbital and Tacrolimus can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Why it happens
Induction of CYP3A4 and P-glycoprotein increases tacrolimus clearance and reduces absorption.
What to do
Prefer a non-inducing anticonvulsant if possible; otherwise monitor tacrolimus troughs frequently and increase the dose, then reduce it when phenobarbital is stopped.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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Other interactions of Tacrolimus
- Adenovirus types 4 and 7 live + Tacrolimus Contraindicated
- Bcg vaccine live + Tacrolimus Contraindicated
- Cidofovir + Tacrolimus Contraindicated
- Cyclosporin + Tacrolimus Contraindicated
- Influenza virus vaccine quadrivalent intranasal + Tacrolimus Contraindicated
- Measles mumps and rubella vaccine live + Tacrolimus Contraindicated
Frequently asked questions
Can I take Phenobarbital with Tacrolimus?
MediHelp rates the interaction as major. Phenobarbital and Tacrolimus can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Phenobarbital strongly induces metabolism and can substantially lower tacrolimus levels, risking rejection.
How serious is the interaction between Phenobarbital and Tacrolimus?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Prefer a non-inducing anticonvulsant if possible; otherwise monitor tacrolimus troughs frequently and increase the dose, then reduce it when phenobarbital is stopped.
What other medicines interact with Tacrolimus?
MediHelp also lists interactions of Tacrolimus with, for example, Adenovirus types 4 and 7 live, Bcg vaccine live, Cidofovir. The full list is on the Tacrolimus page.
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