Antithrombotic Drug Eruptions in Dermatology Practice: Selection Bias, Clinical Phenotypes, and Diagnostic Approaches

Antithrombotic agents are among the most frequently prescribed medications in elderly patients and are essential for the prevention and treatment of cardiovascular and cerebrovascular diseases. Although cutaneous adverse reactions associated with anticoagulants and antiplatelet agents are generally considered uncommon, dermatologists frequently encounter these medications when evaluating patients presenting with pruritic eruptions. This apparent discrepancy may be explained by differences in patient populations. While cardiologists and neurosurgeons manage all patients receiving antithrombotic therapy, dermatologists evaluate a selected population enriched for cutaneous symptoms. This review summarizes the spectrum of cutaneous adverse reactions associated with major antithrombotic agents, including warfarin, heparins, aspirin, ticlopidine, clopidogrel, cilostazol, prasugrel, and direct oral anticoagulants (DOACs). Reported reactions range from common hemorrhagic manifestations to delayed-type hypersensitivity reactions; severe cutaneous adverse reactions, such as drug reaction with eosinophilia and systemic symptoms (DRESS/DIHS), Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), vasculitis, and skin necrosis. Particular emphasis is placed on drug-specific dermatologic phenotypes and diagnostic approaches, including drug-induced lymphocyte stimulation testing, patch testing, and clinicopathological correlation. In addition, Japanese case reports published between 1980 and 2024 are reviewed and integrated with the international literature. These data suggest that antithrombotic agents should not be regarded as a homogeneous dermatologic risk category. Instead, each drug class exhibits characteristic cutaneous reaction patterns that may assist in the differential diagnosis of these reactions in clinical practice. Recognition of these drug-specific phenotypes may facilitate earlier diagnosis, improve interdisciplinary communication, and optimize the management of suspected antithrombotic drug eruptions.