K E Y W O R D S : alternative, cross-reactions, cutaneous adverse drug reactions, delayed-type hypersensitivity, heparins, immediate-type hypersensitivity, intradermal test, patch test, prick test, skin tests Heparins constitute a group of anticoagulants that are widely used in clinical practice for the prophylaxis and treatment of thromboembolic events. Among the adverse events induced by heparins, delayed-type hypersensitivity (DTH) reactions are commonly reported, mostly as eczematous patches localized on the injection sites. 1 Only a few cases of immediate-type hypersensitivity (ITH) reactions have been described, manifesting as urticaria, angioedema, palmoplantar itch, dyspnoea, and anaphylaxis. 2,3