Cephalosporin use in treatment of patients with penicillin allergies.

OBJECTIVE: To review the evidence that supports the use of certain cephalosporins in penicillin-allergic patients. DATA SOURCES: Published articles were identified through Medline and EMBASE (1960-2007) using the search terms penicillin and allergy and cephalosporin and cross-reactivity. Additional sources were identified from the authors' personal collection and the reference bibliographies. STUDY SELECTION: The articles found in the search were limited to the English language and screened for relevance. Review articles and republication of results were excluded. A total of 44 articles reported evidence of cross-reactivity between cephalosporins and penicillins in human and animal studies. Additional references provided background and perspective. DATA SYNTHESIS: Physicians may now prescribe certain cephalosporins in patients with a history of a nonserious, non-life-threatening penicillin reaction. Exclusions include type I anaphylaxis, Stevens-Johnson syndrome, toxic epidermal necrolysis, angioedema, and other potentially life-threatening responses to medication. Recent reports demonstrate that a considerable body of literature describing the cross-reactivity between cephalosporins and penicillin was established based on nonallergic adverse reactions or in vitro studies rather than on clinically relevant immune-mediated reactions. Oral rechallenge and skin testing data support the relationship of the beta-lactam side-chain structures of these drugs as a predictor of cross-reactivity. CONCLUSION: Recent data suggest that the incidence of cross-reactivity among penicillins and cephalosporins is lower than historically reported. Pharmacists should be aware that cephalosporin cross-reactivity in a penicillin-allergic patient is not necessarily a class effect. Dispensing should be evaluated based on the type of allergic manifestations and the drug prescribed.