Onset of penicillin rashes: relation between type of penicillin administered and type of immune reactivity.

In 90 patients with clinical symptoms of penicillin allergy, the onset of the skin reaction was related to the type of penicillin administered (small- or broad-spectrum) and to the type of immune reactivity. Early onset reactions (urticaria, Quincke's edema, Arthus-reactions) were frequently seen after the use of benzylpenicillin, while late onset reactions, mostly macular papular rashes, were mainly seen after the use of aminopenicillins. The clinical symptoms of penicillin hypersensitivity were not related to one single type of immunological (cellular or humoral) reactivity.