Drug interactions
Paracetamol + Phenindione
Severity: Moderate
Paracetamol and Phenindione: moderate 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
Regular paracetamol use can enhance the anticoagulant effect of vitamin K antagonists and raise INR. Phenindione is likely to behave similarly, increasing bleeding risk with sustained paracetamol use.
What this interaction means in plain words
Paracetamol and Phenindione can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Why it happens
Proposed interference with vitamin K-dependent clotting factor synthesis by a paracetamol metabolite; not fully established.
What to do
Monitor INR when paracetamol is used regularly, especially at doses of several grams per day, and adjust phenindione dose accordingly. Occasional low doses generally need no change.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Paracetamol
- Ethanol + Paracetamol Major
- Busulfan + Paracetamol Moderate
- Carbamazepine + Paracetamol Moderate
- Cholestyramine + Paracetamol Moderate
- Felbamate + Paracetamol Moderate
- Fosphenytoin + Paracetamol Moderate
Frequently asked questions
Can I take Paracetamol with Phenindione?
MediHelp rates the interaction as moderate. Paracetamol and Phenindione can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Regular paracetamol use can enhance the anticoagulant effect of vitamin K antagonists and raise INR. Phenindione is likely to behave similarly, increasing bleeding risk with sustained paracetamol use.
How serious is the interaction between Paracetamol and Phenindione?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor INR when paracetamol is used regularly, especially at doses of several grams per day, and adjust phenindione dose accordingly. Occasional low doses generally need no change.
What other medicines interact with Paracetamol?
MediHelp also lists interactions of Paracetamol with, for example, Ethanol, Busulfan, Carbamazepine. The full list is on the Paracetamol page.
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