IgE-mediated hypersensitivity to cephalosporins: cross-reactivity and tolerability of penicillins, monobactams, and carbapenems

J Allergy Clin Immunol. 2010 Nov;126(5):994-9. doi: 10.1016/j.jaci.2010.06.052.


Background: There have been few studies regarding the cross-reactivity and tolerability of penicillins, aztreonam, and carbapenems in large samples of subjects with cephalosporin allergy.

Objective: We sought to evaluate the possibility of using penicillins, monobactams, and carbapenems in subjects with cephalosporin allergy who especially require them.

Methods: We conducted a prospective study of 98 consecutive subjects who had 106 immediate reactions (mostly anaphylactic shock) to cephalosporins and had positive skin test results for these drugs. To assess the cross-reactivity with penicillins, monobactams, and carbapenems and the tolerability of such alternative β-lactams, all subjects underwent skin tests and serum-specific IgE assays with penicillin reagents, as well as skin tests with aztreonam, imipenem/cilastatin, and meropenem. Subjects with negative test results were challenged with meropenem, imipenem/cilastatin, aztreonam, and amoxicillin.

Results: Positive allergologic test results to penicillins were displayed by 25 (25.5%) subjects, including 1 with positive results to all reagents tested and another with a positive result to aztreonam. Another subject had positive results to both ceftazidime and aztreonam. A reaction to cephalosporins with side-chain structures similar or identical to those of penicillins was a significant predictor of cross-reactivity because of an increased 3-fold risk of positive results on allergologic tests with penicillin determinants. Challenges with alternative β-lactams were tolerated, with the exception of 1 urticarial reaction to imipenem/cilastatin.

Conclusions: About 25% of subjects with cephalosporin allergy had positive results to penicillins, 3.1% to aztreonam, 2% to imipenem/cilastatin, and 1% to meropenem. In those who especially require alternative β-lactams, pretreatment skin tests are advisable because negative results indicate tolerability of the β-lactam concerned.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Carbapenems / adverse effects
  • Carbapenems / immunology*
  • Cephalosporins / adverse effects*
  • Cephalosporins / immunology
  • Cross Reactions
  • Drug Hypersensitivity / blood
  • Drug Hypersensitivity / etiology
  • Drug Hypersensitivity / immunology*
  • Female
  • Humans
  • Hypersensitivity, Immediate / chemically induced
  • Hypersensitivity, Immediate / immunology
  • Immunoglobulin E / blood*
  • Immunoglobulin E / immunology
  • Male
  • Middle Aged
  • Monobactams / adverse effects
  • Monobactams / immunology*
  • Penicillins / adverse effects
  • Penicillins / immunology*
  • Skin Tests
  • Young Adult


  • Carbapenems
  • Cephalosporins
  • Monobactams
  • Penicillins
  • Immunoglobulin E