Across the Border: A Metamizole Drug-Induced Liver Injury

Metamizole (dipyrone) is a medication with analgesic, antipyretic, and spasmolytic properties, widely used in Mexico and other Latin American countries. It is often grouped with non-steroidal anti-inflammatory drugs (NSAIDs) due to its pain-relieving and fever-reducing effects, making it a common over-the-counter option. However, concerns over its potential to cause agranulocytosis led to its removal from the U.S. market. Reports of drug-induced liver injury (DILI) related to metamizole are uncommon but noteworthy. Given its frequent use in Latin America and parts of Europe, awareness of this possible adverse effect is important. A 39-year-old man with no prior medical conditions sought medical care for persistent right upper quadrant pain and jaundice lasting two weeks. To address his symptoms, he had been prescribed a compounded medication containing butylscopolamine and metamizole in Ciudad Juárez, Mexico. Shortly after, he noticed yellowing of his skin and eyes, prompting him to seek care in the United States. Laboratory findings indicated a mixed hepatocellular pattern of liver injury (total bilirubin: 6.5, direct bilirubin: 5.1, aspartate aminotransferase: 1,496, alkaline phosphatase: 130, and alanine aminotransferase: 2,579). Additional testing showed elevated transferrin saturation and ferritin levels (82%; 57,700). Imaging of the abdomen revealed periportal edema without other significant abnormalities. A thorough evaluation for viral, autoimmune, and genetic liver diseases yielded negative results. A liver biopsy demonstrated features of portal and lobular hepatitis with eosinophilic infiltration, suggesting DILI. Prussian blue staining did not indicate iron accumulation. Given the timing and exclusion of other causes, the reaction was attributed to the metamizole-containing medication. Discontinuation of the drug and supportive care led to biochemical improvement and resolution of jaundice. Metamizole-related DILI may be underrecognized, particularly in regions where the drug is no longer available. However, it remains widely used in Latin America, relevant for clinicians treating immigrant populations. Recognizing international medication use and obtaining a thorough drug history is essential, especially when managing patients exposed to pharmaceuticals not routinely encountered in the United States.