Idiosyncratic Warfarin-Induced Hepatocellular Injury: A Reversible and Uncommon Occurrence

Warfarin is a widely used oral anticoagulant for the prevention and treatment of thromboembolic events. While its safety profile is well established, hepatotoxicity is an extremely rare but potentially life-threatening adverse effect. We describe a 41-year-old man who developed acute hepatocellular injury within 24 hours of initiating warfarin for upper limb deep vein thrombosis (DVT). He had no past medical history, risk factors for liver disease, or exposure to hepatotoxic agents. Baseline liver function was normal, and alternative causes, including viral and autoimmune hepatitis, were excluded. Marked elevations in alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were observed, which improved rapidly after discontinuing warfarin. The patient was transitioned to apixaban, with complete normalization of liver enzymes on follow-up. This case illustrates a rare but reversible episode of warfarin-induced hepatotoxicity. Early recognition, prompt discontinuation of the drug, and switching to a direct oral anticoagulant (DOAC) facilitated complete recovery. Clinicians should remain vigilant for hepatic injury during warfarin therapy, particularly soon after initiation, to prevent progression to severe dysfunction.