Which Cephalosporins to Use in Penicillin Allergy?

Although allergy to antibiotics is commonly claimed, true allergy to these drugs is often absent http://buff.ly/1tIbcTl

Newer studies suggest that cephalosporins without a beta-lactam side chain may be used relatively safely in patients who are allergic to to penicillin (PCN)

First, it is important to collect a good history and establish that a true allergic reaction to PCN took place. Many patients say they are allergic when in reality they are not. A true allergic reaction to PCN is IgE-mediated and includes any of the following:

- bronchospasm
- angioedema
- hypotension
- urticaria
- pruritic rash

Most PCN allergies are related to the beta-lactam side chain. Therefore, the following cephalsporins which all contain a beta-lactam chain carry a high risk for cross-reactivity and should be avoided:

- Cephalexin
- Cefadroxil
- Ceflaclor
- Cephradine
- Cefprozil
- Ceftriaxone
- Cefpodoxime

Certain cephalosporins can be used cautiously in PCN-allergic patients (using a modified challenge protocol):

- Cefazolin
- Cefuroxime
- Cefdinir
- Cefixime
- Ceftibuten

References:

AANP: Certain Cephalosporins May Be Safe for Patients with Penicillin Allergies. MedPage Today, June 25, 2007.
Penicillin and Cephalosporin allergy - Annals of Allergy, Asthma & Immunology, 2014 http://buff.ly/1ltZntr
Is This Patient Allergic to Penicillin? An Evidence-Based Analysis of the Likelihood of Penicillin Allergy. JAMA. 2001;285:2498-2505.
Practical Aspects of Choosing an Antibiotic for Patients with a Reported Allergy to an Antibiotic. Joan L. Robinson, Tahir Hameed, and Stuart Carr. Clinical Infectious Diseases 2002;35:26–31.
There's a 25% chance that patients with hypersensitivity to cephalosporins will also react to penicillins http://goo.gl/SFyE

IgE-mediated hypersensitivity to cephalosporins: Cross-reactivity and tolerability of penicillins, monobactams, and carbapenems. JACI, 2010 http://goo.gl/MHVz5
Outcomes in the Use of Cephalosporins in Pediatric Patients with a History of Penicillin Allergy http://goo.gl/0HGo4
Image source: Penicillin nucleus, Wikipedia, GNU Free Documentation License.