Although drugs are a common cause of acute immune-mediated thrombocytopenia in humans, drug-induced thrombocytopenia is often not initially recognized. Typically, drug-induced thrombocytopenia occurs 1 to 2 weeks after starting a new drug or abruptly after a single dose when a previous drug has not been used continuously. However, severe drug-induced thrombocytopenia can occur shortly after starting antiplatelet or antithrombotic drugs.