Cephalosporins for Patients with a History of Penicillin Allergy: The Safety of an Oral Test Dose

Background Cephalosporins are often avoided in patients labeled with penicillin allergy due to potential cross-reaction. We describe the utility of an oral cephalosporin test dose in patients with penicillin allergy. Method A retrospective review of all inpatients labeled with penicillin allergy who received a single oral cephalosporin dose, identified through the pharmacy records between April 1, 2004 and October 30, 2008. Results Ninety-seven inpatients met our selection criteria. Type of penicillin reaction was described as rash/hives/pruritis, anaphylaxis, angioedema, and unknown in 53 (54.7%), 10 (10.3%), 7 (7.2%), and 27 (27.8%) cases, respectively. The test dose used was cephalexin 250 mg (56.7%) or 125 mg (35.1%) and cefuroxime axetil 125 mg (8.2%). Reaction to the test dose was noted in 5 (5.2%) patients, including rash (n=2), breathing difficulty (n=2), and asymptomatic eosinophilia (n=1). Breathing difficulty resolved with diphenhydramine/corticosteroids in one case and without any therapy in the other. Cephalosporin therapy was initiated within 3 hours (interquartile range, 2-6 hours) after test dose in 90/93 patients without test-dose reaction. Two (2.2 %) patients developed reaction during treatment: rash (n=1) and angioedema (n=1). One case complained of anxiety, and therapy was interrupted. Test-dose and treatment reactions were transient and easily managed. Conclusions An oral cephalosporin test dose was safe in patients labeled with penicillin allergy and predicted subsequent cephalosporin tolerance in nearly 90% of patients.