Metamizole as a Rare Cause of Drug-Induced Liver Injury

Drug-induced liver injury (DILI) is a heterogenous entity with a wide range of pathogenetic mechanisms and clinical manifestations. DILI is a diagnosis of exclusion. Metamizole (dipyrone) is an analgesic increasingly used in Europe, but there is limited information on its adverse effects. We report the case of a 56-year-old man with acute fever, malaise and general deterioration. Onset of symptoms occurred 12 hours after intake of metamizole for shoulder pain. The patient’s medical history was remarkable for three episodes of an inflammatory syndrome with hepatitis of unknown aetiology during the previous 3 years. However, retrospective enquiry showed each episode was preceded by metamizole intake shortly before symptom onset. Relevant differential diagnoses such as infection, vasculitis, autoimmune or metabolic diseases were excluded. Liver biopsy was compatible with DILI. Discontinuation of metamizole led to rapid clinical improvement and normalization of liver transaminases. Metamizole is a very rare and poorly known cause of DILI with only a few published case reports in the literature. Careful medical history taking is important to identify the causative agent. Prompt recognition and discontinuation of the drug is crucial. Patients must be informed to avoid this medication in future. LEARNING POINTS: Metamizole is a rare cause of drug-induced liver injury (DILI). Taking a systematic medical and drug history is crucial for diagnosing DILI. DILI is a diagnosis of exclusion.