Drug-Induced Liver Injury Associated With the Angiotensin II Receptor Blocker Losartan in a 59-Year-Old Woman With Hypertension: A Case Report

BACKGROUND Drug-induced liver injury is a major cause of acute hepatitis and liver failure, with presentations ranging from asymptomatic elevation of liver enzymes to severe hepatic dysfunction. Diagnosis of drug-induced liver injury is challenging because it mimics other hepatic disorders and requires careful exclusion of alternative etiologies. Losartan, a commonly prescribed angiotensin II receptor blocker for hypertension, is generally safe, but rare cases of hepatotoxicity have been reported. CASE REPORT A 59-year-old South African woman with newly diagnosed hypertension was started on losartan 100 mg daily. After 1 month, she presented with a 3-month history of belching, right-sided back pain, right upper-quadrant discomfort, and dyspepsia. She had no fever, jaundice, alcohol use, or exposure to other hepatotoxins. Laboratory test results revealed markedly elevated alanine aminotransferase (640 IU/L) and aspartate aminotransferase (341 IU/L), with mildly increased alkaline phosphatase (247 IU/L). International normalized ratio, albumin, full blood count, renal function, electrolytes, thyroid profile, and coagulation results were normal. Viral, autoimmune, metabolic, and infectious causes were excluded. Abdominal ultrasound and MRCP showed no abnormalities. Losartan was discontinued and replaced with amlodipine. Liver enzymes improved rapidly and normalized within 1 month, with complete and sustained normalization at 6 months. CONCLUSIONS Although rare, losartan-induced hepatotoxicity should be considered in patients with otherwise unexplained liver enzyme elevation. Early recognition, thorough exclusion of other causes, and prompt discontinuation of losartan typically lead to full recovery, emphasizing the need for timely evaluation in patients receiving angiotensin II receptor blocker therapy.