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Coumadin, Jantoven
Anticoagulant • Vitamin K antagonist
PremiumInhibits vitamin K-dependent clotting factors (II, VII, IX, X)
From the drug index — may include conditions studied rather than approved indications
Typical adult starting point — always confirm against local guidelines
9 curated · 8 major or contraindicated · select a row for management
| Interacting drug | Severity | Effect |
|---|---|---|
| amiodarone | major | Warfarin effect may increase by 30-50%. Onset may be delayed 1-2 weeks. |
| aspirin | major | Significantly increased risk of major bleeding, including GI and intracranial hemorrhage. |
| cocaine | major | Cocaine-induced hypertensive crisis + anticoagulation = severe hemorrhage risk; cardiac arrhythmias may require reversal |
| enzalutamide | major | Dramatically reduced warfarin effect; inadequate anticoagulation |
| fluconazole | major | INR may increase 2-4 fold, causing significant bleeding risk. |
| ibuprofen | major | Dramatically increased bleeding risk. NSAIDs also cause GI erosion, compounding the hemorrhagic risk. |
| metronidazole | major | Increased INR and bleeding risk |
| rifampicin | major | Profound reduction in warfarin anticoagulant effect; INR may drop to sub-therapeutic levels within days, leading to thromboembolic risk. |
| ethanol | moderate | Unpredictable INR fluctuations; increased GI bleeding risk |
Alcohol affects warfarin metabolism unpredictably. Acute intake increases anticoagulant effect; chronic use decreases it.
Published parameters · PMID:15930014
Assembled from: drug index, curated drug database, curated interaction pairs, published PK literature.
