IGHE and erythema multiforme: Type I reactions are immunoglobulin E (IgE)-mediated reactions, such as anaphylaxis; Type II reactions are antibody-mediated reactions such as thrombocytopenia, hemolytic anemia and blood transfusion reactions; Type III reactions are immune-complex-mediated hypersensitivity reactions, such as vasculitis and serum sickness; Type IV reactions are delayed T cell-mediated reactions, such as erythema multiforme, toxic epidermal necrolysis, allergic contact dermatitis.