Primary Care Liaison

Drug allergies

  • Introduction

    This guideline relates to suspected medication allergies in paediatric patients. For more information please visit: Allergy and Immunology : Allergy and Immunology

    Antibiotics are the most common cause of serious allergic drug reactions in children. Other common agents are anaesthetic agents, NSAIDS or aspirin.

    An allergic reaction may involve one or more of the following signs and symptoms:

    Mild to moderate local allergic reaction

    • Swelling of lips, face or eyes
    • Hives or welts. Note: Maculopapular rashes may suggest a non IgE medicated allergic reaction

    Moderate local allergic reaction

    • Abdominal pain or vomiting

    Severe systemic allergic reaction (anaphylaxis)

    • Difficulty breathing
    • Swelling of the tongue and/or throat
    • Difficulty talking
    • Hoarse voice, wheezing or persistent coughing
    • Loss of consciousness and/or collapse
    • Infants and young children appearing pale and floppy

    Severe allergic reaction (anaphylaxis) will typically include multiple organ systems (i.e. hives and respiratory symptoms).

    When to refer

    • ALWAYS refer confirmed or suspected anaphylaxis to the RCH Department of Allergy and Immunology. This is an URGENT REFERRAL.
    • For allergy skin tests
    • For challenge testing  to confirm the diagnosis
    • Where there is no other drug alternative (e.g., insulin, chemotherapy or penicillin) and desensitisation is required to get the child onto the drug without causing a severe allergic reaction (transient intolerance)

    Do not refer 

    • For allergy screening if there is no clear history of allergic reaction
    • When there is a family history of drug allergy and a healthy patient who has not had an allergic reaction to a drug
    • For drug reaction if the reaction was mild, there are alternative drugs available and avoidance is an option for management (e.g., Ceclor reactions)

    Services available closer to home

    Alternative paediatric allergy services available in Victoria include:

    • Public paediatric allergy services:
      • The Northern Hospital
      • Sunshine Hospital
      • Monash Children’s Hospital
    • Consider referral to a private allergist as an alternative to RCH. Options available on ASCIA website: Locate a specialist

    Referral criteria/required information

    The GP at first consultation is in the best position to get the most comprehensive information from parents on the details of an allergic reaction. Please collect and include in your referral as much detail as possible. Referrals may be rejected if information is insufficient to triage appropriately

    Please include:

    • CLEARLY INDICATE if the child has confirmed or suspected ANAPHYLAXIS. The referral will be triaged as urgent
    • Date reaction(s) occurred
    • Allergic reaction signs/symptoms (see mild, moderate and severe symptoms above)
    • Potential causes of reaction(s) e.g., which drug/s?
    • When, where and how did the reaction(s) happen (include timing of onset in relation to dose and duration after cessation of drug)?
    • RAST results

    • Treatment given and patient response
    • Previous or subsequent exposure to allergen

    How to refer

    RCH Specialist Clinics Referral.pdf

    Please complete the above and submit via:

    Suggested pre-referral work-up/management 

    History:

    • Drug: type, amount, form ingested
    • Nature of reaction:

    o    Timing of onset in relation to dose

    o    Duration of reaction after cessation of drug

    • Previous or subsequent exposure to the suspected drug?
    • Drugs taken safely in the past that have not caused allergic reactions

    Diagnostics:

    • RAST test may be helpful for penicillin and penicillin derivatives (eg: penicillin major determinant, benzyl penicillin G, amoxycilloyl).
    • Only RAST test for drug allergy if suspect IgE-mediated reaction (not useful for non IgE mediated)
    • Skin testing should only be performed by a specialist allergist

    • Do not attempt to perform a challenge to the allergen. This should only be done in a specialist allergy unit
    • Interpretation of RAST test or SPT (Skin Prick Test)
      • Test results should be interpreted together with history
      • RAST may be falsely negative
      • Positive allergen-specific IgE (RAST or SPT) in the presence of a clear history of allergic reaction, confirms clinical allergy

    Management:

    • Discontinue the drug
    • If alternative antibiotics are available on the market, choose one of equal efficacy
    • Amoxicillin or penicillin-derivative reactions need avoidance of all penicillin derivative antibiotics
    • Paracetamol can be used as an alternative to aspirin
    • Refer patient to Allergy and Immunology specialist for further management and instruct patient to avoid the specified drug

    Information for families

    Resources and links

    Acknowledgements

    The development of this guideline was coordinated by the Department of Allergy and Immunology (Dr Jo Smart and Dr Paulina Alhucema). Guideline reviewed in January 2025.