Ibuprofen × Warfarin

Ibuprofen and warfarin compete for plasma protein (albumin) binding. The free warfarin fraction rises and its anticoagulant effect intensifies. In parallel, ibuprofen reversibly inhibits platelet aggregation and damages the gastric mucosa – two additional bleeding mechanisms. INR may rise modestly, but gastrointestinal bleeding risk increases independently of INR.

Black or tarry stools (melena), vomiting blood or coffee-ground material, epigastric pain. Less severe presentations: gum bleeding, epistaxis, bruising. Risk multiplies in patients with a history of peptic ulcer disease.

For analgesia in a warfarinised patient, paracetamol is preferred (up to 2 g/day, short courses). If chronic NSAID therapy is needed, switch to a selective COX-2 inhibitor (celecoxib) with proton pump inhibitor cover and frequent INR monitoring. Topical NSAIDs (gels, creams) deliver minimal systemic absorption and are acceptable.