Drug Allergy


A drug allergy is defined as an immune-mediated hypersensitivity reaction to a medicinal product and may be divided into Immunoglobulin E (IgE) mediated (immediate-onset) reactions and non IgE-mediated (delayed-onset) reactions (RCPCH 2011).

A good history is essential but recall for the historian can be difficult as time passes so the most detailed history needs to be taken on the first encounter with the patient / family after the event.

IgE – mediated allergic reactions are rapid in onset, much as they are for food.



  • Any cases of anaphylaxis to a drug for consideration of an Allergy Clinic appointment or advice
  • Multiple antibiotic allergies from different classes of antibiotic for consideration of an Allergy clinic appointment or advice


No need to refer: Cases of Penicillin or other single-class antibiotic allergy, if alternative antibiotics are tolerated.


Date                            January 2022

Review Date               January 2023

Authors:                     Simon Bedwani, Consultant Paediatrician, RCHT

                                    Dr S Burns GP RMS


Version No.  1.2