S5872 Rare but Real: Doxycycline-Induced Hepatocellular Liver Injury

Introduction: Drug-induced liver injury (DILI) is a leading cause of acute liver failure in the United States. It presents with a wide range of symptoms, including fatigue, abdominal pain, jaundice, fever, or can be asymptomatic. In severe cases, it may progress to liver failure. Several antibiotics are commonly associated with DILI, such as amoxicillin-clavulanate, sulfonamides, and isoniazid. However, doxycycline-induced DILI is rare. We present a case of DILI associated with doxycycline use. Case Description/Methods: A 45-year-old man with a history of attention deficit hyperactivity disorder presented with 1 day of epigastric pain and vomiting. He denied fever, rash, or jaundice. He had been diagnosed with Lyme disease and started on doxycycline 1 week prior to the onset of symptoms. Vital signs showed no fever and were unremarkable. Physical exam revealed right upper quadrant tenderness without peritoneal signs. Laboratory workup showed a hepatocellular pattern of liver injury: aspartate aminotransferase 453 U/L, alanine aminotransferase 688 U/L, alkaline phosphatase 115 U/L, and total bilirubin 2.3 mg/dL with indirect predominance. Viral hepatitis serologies and autoimmune markers were negative. Abdominal computed tomography and MRI showed no structural abnormalities. Doxycycline was discontinued, leading to rapid improvement in liver function tests (LFT) within 48-72 hours. Discussion: Doxycycline-induced liver injury is rare and may present with varying patterns of liver injury, including hepatocellular, cholestatic, or mixed types. Onset typically occurs within 1–2 weeks of initiating the drug. A high index of suspicion is crucial, particularly in endemic regions for Lyme disease, where doxycycline is commonly used as a first-line antibiotic. This case emphasizes the importance of high suspicion of DILI, even with antibiotics considered relatively safe.