Leflunomide-Induced Severe Cutaneous Adverse Reaction, Severe Drug-Induced Liver Injury With Hepatic Encephalopathy, and Hemophagocytic Lymphohistiocytosis: A Case Report.

Leflunomide, a disease-modifying antirheumatic drug (DMARD) employed for the treatment of rheumatoid arthritis, generally holds a reputation for safety. However, it occasionally induces severe adverse reactions, including acute liver failure, drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome, and hemophagocytic lymphohistiocytosis (HLH). This report details the case of a 46-year-old female who developed these complications shortly after commencing leflunomide therapy, manifesting severe cutaneous adverse reactions, severe drug-induced liver injury with Grade I hepatic encephalopathy, and subsequently HLH. Her clinical journey underscores the critical need for vigilance and prompt management in patients showing signs of severe drug-induced reactions. Following the HLH-94 treatment protocol, her condition improved significantly, highlighting the efficacy of immediate and appropriate intervention. This case not only exemplifies the potential severe complications associated with leflunomide but also illustrates the life-saving potential of early diagnosis and treatment in cases of drug-induced HLH and DRESS syndrome. This case contributes to the literature by underscoring the complexities of managing rare but severe side effects of commonly used medications.