Drug interactions
Nafcillin + Ulipristal
Severity: Major
Nafcillin 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
Nafcillin induces CYP3A4 and may lower ulipristal concentrations, which could reduce emergency contraceptive efficacy. The label advises avoiding ulipristal with CYP3A4 inducers.
What this interaction means in plain words
Nafcillin 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
CYP3A4 induction by nafcillin increases ulipristal metabolism.
What to do
Avoid ulipristal and use a copper IUD, or levonorgestrel with a doubled dose where appropriate. Inducer effects may persist for weeks after stopping nafcillin.
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 Nafcillin with Ulipristal?
MediHelp rates the interaction as major. Nafcillin 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. Nafcillin induces CYP3A4 and may lower ulipristal concentrations, which could reduce emergency contraceptive efficacy. The label advises avoiding ulipristal with CYP3A4 inducers.
How serious is the interaction between Nafcillin 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 IUD, or levonorgestrel with a doubled dose where appropriate. Inducer effects may persist for weeks after stopping nafcillin.
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