Drug interactions
Dicloxacillin + Phenindione
Severity: Major
Dicloxacillin and Phenindione: 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
Dicloxacillin has been reported to reduce the anticoagulant effect of vitamin K antagonists such as warfarin, and a similar effect is expected with phenindione. Loss of anticoagulation raises the risk of thromboembolism, and the INR may fall during treatment and rise again after the antibiotic is stopped.
What this interaction means in plain words
Dicloxacillin and Phenindione 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
Probable induction of hepatic enzymes by dicloxacillin increasing metabolism of the anticoagulant.
What to do
Check INR within a few days of starting dicloxacillin and adjust the phenindione dose; recheck after stopping the antibiotic as the dose may need to be reduced again.
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 Dicloxacillin
- Atogepant + Dicloxacillin Moderate
- Axitinib + Dicloxacillin Moderate
- Bcg vaccine live + Dicloxacillin Moderate
- Cholera vaccine + Dicloxacillin Moderate
- Demeclocycline + Dicloxacillin Moderate
- Dicloxacillin + Doxycycline Moderate
Frequently asked questions
Can I take Dicloxacillin with Phenindione?
MediHelp rates the interaction as major. Dicloxacillin and Phenindione 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. Dicloxacillin has been reported to reduce the anticoagulant effect of vitamin K antagonists such as warfarin, and a similar effect is expected with phenindione. Loss of anticoagulation raises the risk of thromboembolism, and the INR may fall during treatment and rise again after the antibiotic is stopped.
How serious is the interaction between Dicloxacillin and Phenindione?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Check INR within a few days of starting dicloxacillin and adjust the phenindione dose; recheck after stopping the antibiotic as the dose may need to be reduced again.
What other medicines interact with Dicloxacillin?
MediHelp also lists interactions of Dicloxacillin with, for example, Atogepant, Axitinib, Bcg vaccine live. The full list is on the Dicloxacillin page.
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