Lack of allergic cross-reactivity to cephalosporins among patients allergic to penicillins

Background There are some contradicting data about clinical allergic cross- reactivity to cephalosporins among patients who have had a previous allergi c reaction to penicillins. Objective The purpose of this study was to assess the safety of administeri ng cephalosporins to penicillin-allergic patients. Methods The diagnosis of penicillin allergy was made by positive skin tests to penicillin reagents and/or provocation tests with the penicillin suspec ted of causing the allergic reaction. To assess the clinical tolerance to c ephalosporins, 41 well-characterized penicillin allergic patients diagnosed by positive skin tests and/or provocation tests were challenged with three cephalosporins that do not share the same side chain to the penicillin tha t induced the reactions: cephazoline, cefuroxime and ceftriaxone. Results Skin prick and intradermal tests with all cephalosporins tested wer e negative. All penicillin-allergic patients tolerated therapeutic doses of the three cephalosporins tested (cephazoline, cefuroxime and ceftriaxone) without any ill effect. Conclusion These results indicate that the risk of suffering from an allerg ic reaction on administering cephalosporins to penicillin-allergic patients seems to be very low, provided that cephalosporins with a different side c hain to the penicillin responsible for the allergic reaction are used.