Haemolytic anaemia and thrombocytopenia following phenobarbital therapy for alcohol withdrawal.

Drug-induced immune haemolytic anaemia (DIIHA) is a rare but potentially life-threatening condition. Phenobarbital is increasingly used for the management of alcohol withdrawal; however, haematologic toxicity is infrequently reported. We describe a man in his 50s admitted for alcohol withdrawal who developed acute anaemia and thrombocytopenia shortly after initiation of phenobarbital. Laboratory findings were consistent with haemolysis, including undetectable haptoglobin and indirect hyperbilirubinaemia, although the direct antiglobulin test was negative. Alternative causes were excluded. Following discontinuation of phenobarbital, haematologic parameters improved rapidly. This case highlights a probable instance of phenobarbital-associated haemolysis with thrombocytopenia and emphasises the importance of recognising DIIHA even in the absence of a positive antiglobulin test.