- Phenobarbital can cause immune haemolytic anaemia with thrombocytopenia during alcohol withdrawal, a rare but potentially life threatening adverse effect.
- Laboratory evidence showed haemolysis: undetectable haptoglobin and indirect hyperbilirubinaemia despite a negative direct antiglobulin test.
- Haematological parameters improved rapidly after phenobarbital cessation, highlighting need to consider drug induced haemolysis even with negative antiglobulin testing.
BMJ Case Rep. 2026 Sep 17;19(9):e275025. doi: 10.1136/bcr-2026-275025.
ABSTRACT
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.
PMID:42754353 | DOI:10.1136/bcr-2026-275025
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