When a Budget-Friendly Drug Leads to a Premium Diagnosis: A Case Report of Severe Cholestasis Following Amoxicillin-Clavulanate Use.

Drug-induced liver injury (DILI) is a rare but significant complication of commonly prescribed medications. This case describes a 69-year-old female presenting with clinical and laboratory features of mixed type liver injury, bisalbuminemia, and pseudohyponatremia. An extensive evaluation for obstructive, autoimmune, and infectious hepatitis yielded inconclusive results, necessitating advanced imaging and a liver biopsy. The biopsy revealed chronic hepatitis of unspecified etiology. On further inquiry, the patient disclosed having used amoxicillin-clavulanate for sinusitis 4 weeks prior to presentation, implicating this medication as the probable cause of her symptoms. The patient's condition improved with supportive care, with normalization of liver function within 4 months. This case underscores the importance of obtaining a detailed medication history to avoid unnecessary and costly diagnostic evaluations. Physicians must remain vigilant about rare adverse effects of commonly prescribed drugs and recognize their characteristic clinical patterns. Early identification and management can prevent complications, reduce unnecessary interventions, and optimize patient outcomes.