MODERATE — Monitor Closely
FDA-documented interaction, though clinical significance is moderate. INR monitoring recommended when starting or stopping omeprazole.
Evidence level: STRONG
Omeprazole (Prilosec) may modestly increase warfarin blood-thinning effect. While less dramatic than some other warfarin interactions, your clotting should still be monitored when starting or stopping omeprazole.
Omeprazole inhibits CYP2C19, which metabolizes warfarin R-enantiomer. May modestly increase INR. FDA warfarin label lists omeprazole as potentially increasing anticoagulant effect. Clinical significance is moderate.
Get your INR checked if starting or stopping omeprazole while on warfarin. This is a less severe interaction than many warfarin combinations, but monitoring is still prudent.
Take Omeprazole 30 minutes before a meal — PPIs must be activated by acid pumps that turn on when you eat. Warfarin can be taken with the meal or at a separate time. PPIs reduce stomach acid, which can affect absorption of many acid-dependent compounds.
Higher risk with: older age (65+), history of GI bleeding, concurrent use of multiple blood-thinning agents, liver disease, heavy alcohol use, recent surgery.
Easy bruising, prolonged bleeding from cuts, blood in stool
Check INR when starting/stopping omeprazole. Pantoprazole may have less CYP2C19 inhibition. Effect is usually modest.
This medication combination requires careful medical oversight. Your doctor or anticoagulation clinic can adjust doses or select alternatives with fewer bleeding risks. Frequent INR monitoring is essential.
Omeprazole (Prilosec) may modestly increase warfarin blood-thinning effect. While less dramatic than some other warfarin interactions, your clotting should still be monitored when starting or stopping omeprazole.
Take Omeprazole 30 minutes before a meal — PPIs must be activated by acid pumps that turn on when you eat. Warfarin can be taken with the meal or at a separate time. PPIs reduce stomach acid, which can affect absorption of many acid-dependent compounds.
Easy bruising, prolonged bleeding from cuts, blood in stool
This medication combination requires careful medical oversight. Your doctor or anticoagulation clinic can adjust doses or select alternatives with fewer bleeding risks. Frequent INR monitoring is essential.
Check INR when starting/stopping omeprazole. Pantoprazole may have less CYP2C19 inhibition. Effect is usually modest.
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