Cephalosporins can be prescribed safely for pencillin allergic patients

I have been asked this question weekly for the last 12 years so here are the references to confirm that it is ok to give Cephalosporins in patients allergic to pencillin.

Summary articles:

#1. Journal of Family Practice, February 2006

* The widely quoted cross-allergy risk of 10% between penicillin and cephalosporins is a myth (A).

* Cephalothin, cephalexin, cefadroxil, and cefazolin confer an increased risk of allergic reaction among patients with penicillin allergy (B).

* Cefprozil, cefuroxime, cefpodoxime, ceftazidime, and ceftriaxone do not increase risk of an allergic reaction (B).

Undoubtedly you have patients who say they are allergic to penicillin but have difficulty recalling details of the reactions they experienced. To be safe, we often label these patients as penicillin-allergic without further questioning and withhold not only penicillins but cephalosporins due to concerns about potential cross-reactivity and resultant IgE-mediated, type I reactions. But even for patients truly allergic to penicillin, is the concern over cephalosporins justified? It depends on the specific agent. What is certain is that a blanket dismissal of all cephalosporins is unfounded.

The truth about the myth

Despite myriad studies spanning decades and involving varied patient populations, results have not conclusively established that penicillin allergy increases the risk of an allergic reaction to cephalosporins, compared with the incidence of a primary (and unrelated) cephalosporin allergy.

* Results

True incidence of reactions to cephalosporins

The most frequent reactions to cephalosporins are non-pruritic, non-urticarial rashes, which occur in 1.0% to 2.8% of patients; (4-8) for most, the mechanism is idiopathic and not a contraindication for future use. (38) Retrospective studies suggest a 1% to 3% incidence of immune or allergic reactions to cephalosporins independent of any history of penicillin/amoxicillin allergy. (31) Anaphylactic reactions from cephalosporins are extremely rare, with the risk estimated at 0.0001% to 0.1%. (31,38) A seminal study suggested approximately 0.004% to 0.015% of treatment courses with penicillin results in anaphylaxis. (5,9-11) Several studies suggest that cephalosporin-induced anaphylaxis occurs no more frequently among patients with known penicillin allergy than among those without such allergy. (23,27,38-41)

#2. Annals of Allergy, Asthma, and Immunology, February 1995


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