Drug interactions
Phenobarbital + Ulipristal
Severity: Major
Phenobarbital and Ulipristal: 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 induces CYP3A4 and can lower ulipristal concentrations, reducing the likelihood that emergency contraception will work.
What this interaction means in plain words
Phenobarbital and Ulipristal 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
Phenobarbital induces CYP3A4, increasing ulipristal metabolism.
What to do
Avoid ulipristal and use a copper intrauterine device. Induction may persist for weeks after 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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Frequently asked questions
Can I take Phenobarbital with Ulipristal?
MediHelp rates the interaction as major. Phenobarbital and Ulipristal 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 induces CYP3A4 and can lower ulipristal concentrations, reducing the likelihood that emergency contraception will work.
How serious is the interaction between Phenobarbital and Ulipristal?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid ulipristal and use a copper intrauterine device. Induction may persist for weeks after phenobarbital is stopped.
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