Practice Change Page

In patients allergic to penicillin, consider second and third generation cephalosporins for life threatening infections

BMJ 2007; 335 doi: http://dx.doi.org/10.1136/bmj.39372.829676.47 (Published 08 November 2007) Cite this as: BMJ 2007;335:991
  1. Scott Pegler, principal pharmacist, medicines information manager1,
  2. Brendan Healy, specialist registrar in infectious diseases and microbiology2
  1. 1Morriston Hospital, Swansea NHS Trust, Swansea SA6 6NL
  2. 2NPHS Wales, Microbiology Department, University Hospital of Wales, Cardiff CF14 4XW
  1. Correspondence to: S Peglerscott.pegler{at}swansea-tr.wales.nhs.uk
  • Accepted 16 July 2007

Key points

  • True penicillin allergy occurs in 7-23% of patients who give a history of penicillin allergy

  • The frequently cited figure of 10% cross reactivity between penicillin and cephalosporins is an overestimate

  • Cross reactivity between penicillins and second and third generation cephalosporins is low and may be lower than the cross reactivity between penicillins and unrelated antibiotics

  • Anaphylaxis with cephalosporins is rare (0.1-0.0001%)

  • In life threatening infections such as bacterial meningitis, septicaemia, and severe respiratory tract infections, consider using second and third generation cephalosporins even in patients with a history of penicillin allergy

The clinical problem

Many patients claim to be allergic to penicillin. For those confirmed as being truly allergic (type 1 allergy, with features of urticaria, pruritic rash, etc), the cited overall rate of 10% cross reactivity between penicillin and cephalosporins is an overestimate.1 For life threatening infections such as bacterial meningitis, septicaemia, and severe respiratory tract infections in which a non-cephalosporin antibiotic would be suboptimal, consider giving a second or third generation cephalosporin: ceftriaxone, cefotaxime, cefuroxime, ceftazidime, as clinically appropriate.

The evidence for change

The term “allergy” is often applied incorrectly by both patients and doctors to any adverse reaction that …

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