Metamizole use by Latino immigrants: a common and potentially harmful home remedy

A 4-year-old boy presented with fever, septic arthritis, and persistent neutropenia. Bone marrow biopsy revealed no evidence of neoplasia. Additional history disclosed that the patient had been given metamizole for pain before onset of his illness. Metamizole, a nonsteroidal antiinflammatory agent, is prohibited in the United States because of the risk of agranulocytosis but is widely used in Mexico and other countries. The increasing number of Latinos in the United States and the extensive cross-border transfer of medicines raise concerns that metamizole use and associated complications may become more frequent. After identification of the index patient, additional inquiry revealed that the patient's mother was hospitalized previously for overwhelming sepsis associated with metamizole use. These cases prompted an investigation of metamizole use in an urban pediatric clinic, which revealed that 35% of Spanish-speaking Latino families had used metamizole; 25% of these families had purchased the medication in the United States. We conclude that metamizole use is common and may be underrecognized in immigrant Latino patients. Physicians in the United States, especially those who practice primary care, hematology/oncology, and infectious diseases, must be aware of the availability and use of metamizole in specific patient populations and its potential for harmful side effects.