Administration of β-lactam antibiotics to patients with reported penicillin allergy in the emergency department

Am J Emerg Med. 2023 Jun:68:119-123. doi: 10.1016/j.ajem.2023.03.013. Epub 2023 Mar 21.


Background: β-lactam antibiotics are amongst the most commonly prescribed medications in the Emergency Department (ED) due to their role in empiric sepsis therapy; however, inferior therapeutic options are often utilized due to a reported allergy; penicillin (PCN) being most frequent. In the United States, 10% of the population endorses an allergic reaction to PCN while <1% experience IgE-mediated reactions. This study aimed to evaluate the frequency and outcome of patients in the ED whose PCN allergies were challenged with β-lactam antibiotics.

Methods: We conducted a retrospective chart review of patients in the ED at an academic medical center aged ≥18, and who received a β-lactam despite a reported PCN allergy between January 2015 and December 2019. Patients who did not receive a β-lactam or did not report a PCN allergy prior to administration were excluded. The primary outcome was the frequency of IgE-mediated reactions in response to β-lactam administration. A secondary outcome assessed the frequency of continuation of β-lactams upon admission from the ED.

Results: 819 patients were included (66% female) with prior reported PCN reactions: hives (22.5%), rash (15.4%), swelling (6.2%), anaphylaxis (3.5%), other (12.1%), or undocumented on medical electronic record (40.3%). No patients experienced an IgE-mediated reaction to the β-lactam administered in the ED. Previously reported allergies had no effect on the continuation of β-lactams when admitted or discharged (OR: 1, 95% CI: 0.7-1.44). Patients who had a history of an IgE-mediated penicillin allergy were frequently continued (77%) on a β-lactam after leaving the ED via admission or discharge.

Conclusion: β-lactam administration in patients with previously reported PCN allergies did not result in any IgE-mediated reactions nor in an increase in adverse reactions. Our data contributes to the body of evidence that supports the administration of β-lactams to patients with documented PCN allergies.

Keywords: Allergy; Antibiotics; beta lactam.

MeSH terms

  • Anti-Bacterial Agents / adverse effects
  • Drug Hypersensitivity* / epidemiology
  • Drug Hypersensitivity* / etiology
  • Emergency Service, Hospital
  • Female
  • Humans
  • Immunoglobulin E
  • Male
  • Monobactams
  • Penicillins / adverse effects
  • Retrospective Studies
  • Urticaria* / drug therapy
  • beta-Lactams / adverse effects


  • Anti-Bacterial Agents
  • Penicillins
  • beta-Lactams
  • Monobactams
  • Immunoglobulin E