Antiphospholipid antibody syndrome (APS) may rarely present with isolated thrombocytopenia that may be diagnosed and treated as immune thrombocytopenic purpura. A 32-year-old woman was given eltrombopag (a thrombopoietin receptor agonist) to treat presumed immune thrombocytopenic purpura. She developed catastrophic APS, with multiple ischaemic infarcts, microvascular coronary thrombosis and digital gangrene. She improved after stopping eltrombopag and starting immunotherapy (corticosteroids, intravenous immunoglobulin and rituximab) but was left with significant neurological morbidity.