Petechiae and non-palpable purpura (ecchymoses) secondary to medications occur as a result of hemorrhage into the skin. Medications that cause thrombocytopenia or alter platelet function manifest with petechiae and ecchymoses. Chemotherapeutic agents can cause generalized bone marrow suppression leading to thrombocytopenia. Bleomycin has been reported to cause endothelial damage and leakage resulting in purpura.

Uncommonly, epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors have been associated with purpuric skin lesions on the lower extremities, including purpuric macules or papules with confluent plaques, sometimes in an annular configuration; non-follicular purpuric pustules; and xerotic purpuric lesions. See also EGFR inhibitor-induced eruption.

Drug-induced thrombotic thrombocytopenic purpura (TTP) may occur secondary to medication use. It is a life-threatening, multisystem disease. There is strong literature evidence of ticlopidine as a trigger of TTP. Other triggers of TTP frequently reported include interferon alpha (IFN-alpha) therapy, cyclosporine, quinine, and clopidogrel.