S5820 Famotidine-Induced Hepatocellular Injury in Pregnancy: A Diagnostic Challenge in a Patient With Ulcerative Colitis and Cholelithiasis

Introduction: Elevation of liver enzymes in pregnancy often prompts evaluation for viral hepatitis, autoimmune liver disease, or cholestasis. However, medication-induced hepatotoxicity remains under-recognized, particularly with widely used agents such as famotidine. We report a case of hepatocellular injury associated with famotidine use in a pregnant woman with ulcerative colitis (UC) and incidental cholelithiasis. Case Description/Methods: A 28-year-old woman with a history of UC (diagnosed 2015) presented at 27 weeks’ gestation with asymptomatic transaminitis. Laboratory workup showed alanine aminotransferase 481 U/L, aspartate aminotransferase 149 U/L, Alk Phos 135 U/L, and normal bilirubin. She was on stable mesalamine therapy with no UC flare since 2020. Ultrasound revealed hepatic steatosis and multiple mobile gallstones without cholecystitis. Autoimmune and viral hepatitis panels were negative. Notably, the patient had started famotidine (Pepcid) for reflux during pregnancy. Upon discontinuation of famotidine, her liver function tests (LFT) improved significantly over 2 weeks without additional intervention. Liver enzymes continued to decline at one-month follow-up. Colonoscopy confirmed only mildly active chronic colitis, and no flare symptoms were noted during follow-up. Discussion: Famotidine is commonly used in pregnancy for GERD and is generally considered safe. However, rare reports link it to idiosyncratic hepatocellular injury. In this case, the temporal relationship between famotidine use and abrupt LFT elevation, followed by resolution upon cessation, supports a diagnosis of famotidine-induced liver injury. The absence of symptomatic UC activity or biliary obstruction further supports drug-related hepatotoxicity. The case underscores the importance of comprehensive medication review when evaluating abnormal LFTs, even in patients with coexisting hepatobiliary conditions. This case highlights a rare instance of famotidine-associated hepatocellular injury in pregnancy. Clinicians should maintain a high index of suspicion for medication-related liver enzyme abnormalities, even with widely used and presumed safe agents. Discontinuation of the offending agent can lead to rapid resolution and prevent unnecessary invasive diagnostics.