Can You Take Warfarin with Paracetamol?
Last reviewed: · Source: US FDA drug label database
Paracetamol is the safest painkiller on warfarin, but regular use (more than a few days) can raise your INR — get an extra INR check if you need it daily.
Is it safe to take Warfarin with Paracetamol?
Paracetamol is the recommended painkiller for people on warfarin because it doesn't cause the bleeding risk of NSAIDs. However, regular full-dose paracetamol (around 2-4g daily for a week or more) can enhance warfarin's effect and raise the INR, increasing bleeding risk. Occasional doses are fine without any special measures; sustained daily use warrants an earlier INR check so your dose can be adjusted.
How do Warfarin and Paracetamol interact?
Paracetamol's metabolite NAPQI inhibits vitamin K-dependent carboxylase (VKORC1 pathway), potentiating warfarin's anticoagulant effect. Studies show regular paracetamol ≥2g/day can raise INR measurably within about a week; occasional dosing has negligible effect.
Data sourced from the US Food and Drug Administration (FDA) drug label database: OpenFDA warfarin label — acetaminophen interaction.
Who should be careful?
Anyone on warfarin needing daily paracetamol for more than 3-5 days, the elderly, people with unstable INRs, and those with liver impairment or low body weight.
What if I've already taken Warfarin and Paracetamol?
Occasional use: no action. Daily use for several days: arrange an INR check within the week and inform your anticoagulation clinic. Report unusual bruising, prolonged bleeding, blood in urine or stools.
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Frequently Asked Questions
Can I take paracetamol with warfarin?
Yes — it's the painkiller of choice on warfarin. For regular daily use beyond a few days, get an earlier INR check.
How much paracetamol is safe on warfarin?
Standard doses for occasional pain are fine. If you need 2g+ daily for a week or more, your INR should be monitored more closely.
Why can't I take ibuprofen on warfarin?
NSAIDs both irritate the stomach and impair platelets, multiplying bleed risk on top of warfarin. See our warfarin and ibuprofen page.
What bleeding signs should I watch for?
Unexplained bruising, nosebleeds that won't stop, pink/red urine, black stools, or any bleeding that seems excessive. Contact your anticoagulation service.