Major
Diclofenac × Warfarin
Non-steroidal anti-inflammatory drugs (NSAIDs)×Vitamin K antagonist anticoagulants
Mechanism
Diclofenac (NSAID) inhibits platelet aggregation, injures the gastric mucosa, and weakly displaces warfarin from albumin binding. Additive GI bleeding risk independent of INR.
Symptoms
Gum bleeding, epistaxis, bruising without trauma, blood in urine or stool, menorrhagia. Severe cases include gastrointestinal or intracranial haemorrhage. Risk rises in patients over 65 and with prior peptic ulcer disease.
Management
Avoid chronic diclofenac on warfarin. For analgesia, choose paracetamol (up to 2 g/day for short courses). For chronic NSAID needs, use a selective COX-2 inhibitor (celecoxib) under pantoprazole cover.
Check the full regimen, not just this pair
Opens the checker with these two drugs prefilled. Add the rest of the regimen and recompute additive risks.