Correctly applying penicillin allergy labels in children

Approx 10% of parents will report a penicillin allergy in their child, the literature suggests that GP recording is approx. 2.9% whilst the true amount of penicillin allergy is < 0.1% in children. 6% of the UK general adult population are labelled (often incorrectly) as having a penicillin allergy, increasing to 15% of hospitalised patients.

Unfortunately, penicillin allergy labels are associated with negative outcomes for patients, healthcare systems and wider society and include increased mortality, higher healthcare related costs and increase in antimicrobial resistance (AMR). These associated harms are thought to be due to the use of alternative, non-beta-lactam, antibiotics and are largely avoidable because 95% of patients labelled with a penicillin allergy are able to tolerate a penicillin after formal allergy assessment.

Avoiding incorrectly labelling adults and children with a penicillin allergy is paramount. Many patients (especially children) are given a penicillin allergy label if they develop a rash or gastrointestinal symptoms after starting antibiotics. Type 1 hypersensitivity reactions to penicillin almost always occur within an hour of a penicillin antibiotic and may involve the following symptoms and signs:

  • Urticarial skin rash
  • Angioedema
  • Shortness of breath
  • Wheezing
  • Anaphylaxis

In the event of these symptoms occurring within an hour of the commencement of a penicillin, the patient should be labelled as having a penicillin allergy (penA) and further doses of penicillin should be avoided and a non-penicillin antibiotic prescribed instead. If symptoms develop beyond an hour of starting a penicillin and are mild, the patient should not be labelled as having a penA and antibiotics should be continued. Of note, if a child has a mild rash more than one hour after administration of a dose of penicillin and the child is given penicillin again then 4-6% will have a repeat mild benign rash with 94-96% having no rash or other symptoms

Think twice before labelling a child with a penicillin allergy as it will have long-term implications for them.


  • West, Smith CJ, Pavitt SH, et al. ‘Warning: allergic to penicillin’: association between penicillin allergy status in 2.3 million NHS general practice electronic health records, antibiotic prescribing and health outcomes. Journal of Antimicrobial Chemotherapy (JAC) 2019; 74(7): 2075-82.
  • Powell N, Honeyford K, oe J. Impact of penicillin allergy records on antibiotic costs and length of hospital stay: a single-centre observational retrospective cohort. The Journal of hospital infection 2020; 106(1): 35-42.
  • Krah NM, Jones TW, Lake J, Hersh AL. The impact of antibiotic allergy labels on antibiotic exposure, clinical outcomes, and healthcare costs: A systematic review. Infection Control and Hospital Epidemiology 2021; 42(5): 530-48.
  • DesBiens M, Scalia P, Ravikumar S, Glick A, Erinne O. Most patients tolerate penicillin administration despite history of nonanaphylactic penicillin allergy: A systematic review and meta-analysis. Open Forum Infectious Diseases 2018; 5(Supplement 1): S554.

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