Romano A, et al. - Studies performed since 1990 on samples of at least 30 subjects with a documented IgE(immunoglobulin E)-mediated hypersensitivity to penicillins have found a rate of positive responses to allergy tests with cephalosporins ranging from 0% to 27%. Herein, the goal was to assess the cross-reactivity with cephalosporins and evaluate the possibility of using cephalosporins in penicillin-allergic subjects. Findings revealed that cross-reactivity between penicillins and cephalosporins appeared to be predominantly associated with side chain similarity or identity. Additionally, cephalosporins like cefuroxime and ceftriaxone that have side chain determinants different from those of penicillins and are negative in pretreatment skin testing could treat subjects with an IgE-mediated hypersensitivity to penicillins.