How do I know if my child has a drug allergy?

Written by: Professor George Du Toit
Published: | Updated: 04/09/2020
Edited by: Cameron Gibson-Watt

We asked leading paediatric allergist, Professor George Du Toit, to explain more about drug allergies in children, what the symptoms of an allergic reaction might look like and what you should do if your child experiences one.



What are the typical symptoms of an allergic reaction to a drug?

Adverse reactions to drugs can generally be classified as allergic (or immune-based), or non-allergic. Typical immediate-onset allergic reactions are thankfully rare as they can be severe and even life-threatening. Symptoms may include hives, swelling, vomiting, wheezing and occasionally, anaphylaxis. Non-allergic adverse reactions are more common, many of these are predictable and are often dose-dependent; an example being vomiting and gastrointestinal upset after commencing oral antibiotics.


If I have an allergy to a certain drug, will my child be allergic too?

Medication allergies, such as a penicillin allergy are generally not inherited. The purity of medications such as penicillin has also improved over time so the penicillin your grandmother reacted to would be different from the medications currently in use. However, there are some adverse reactions to drugs that may be passed on; for example, certain patients (Han Chinese) may be more susceptible to carbamazepine cutaneous reactions.


Can I test my child before giving them the medication?

There are diagnostic tests that can be performed if a drug allergy is suspected but the testing approach and accuracy depend on the specific drug under investigation. For example, antibiotics are best tested through a drug provocation test where small increments are given in a safe and controlled setting of the index antibiotic. This is only performed if the initial reaction was not severe. These are typically negative which implies that the rash and symptoms associated with the reaction are likely to have arisen due to the underlying infection and not the medication (such as ibuprofen or amoxicillin) that was given for the illness.


For other drugs, such as anaesthetic agents, these can be tested by intradermal tests and for others, blood tests such as latex and chlorhexidine. Any suspicion of drug allergy should be assessed by a specialist allergy clinic.


Being allergic to pollens and food does not put you at risk of drug allergy.


What should I do if my child develops an allergic reaction?

If a drug-induced reaction is suspected, then the next dose should be omitted and medical advice sought. This is especially important if your child is experiencing immediate-onset allergy symptoms or troubling delayed symptoms, such as redness and peeling of the skin and mucus membranes (the lips and eyes). You should always report any adverse reactions to your doctor and stop the medication. Your doctor will then advise on frontline analgesics which are safe for your child.


If you are worried your child might have a drug allergy and would like to talk to a specialist, visit Professor George Du Toit’s Top Doctors profile and book a consultation with him.

By Professor George Du Toit
Paediatric allergy & immunology

Professor George Du Toit is a consultant paediatrician with more than two decades of experience treating and managing patients with complex allergies such as eczema, food allergy, asthma, antibiotic allergy and hayfever. His team aim to provide patient-centered and responsive care, backed by the highest safety standards and are supported by an experienced team of Nurses, Psychologists, Dietitians and Practice Management staff.

Professor Du Toit loves his chosen niche of paediatric medicine and this is reflected in his excellent patient/family feedback. Professor Du Toit holds private clinics at the Portland Hospital, Great Ormond Street Hospital and in New Malden, Surrey; his NHS practice is at the Evelina Children's Hospital, London.

Professor Du Toit is one of the Directors of The Food Allergy Immunotherapy Centre (TFAIC) based at GOSH. This service provides desensitisation for peanut (using Palforzia) as well as other food allergies (cashew and sesame commencing 2023). Professor Du Toit oversees Oral Food Challenge tests for the diagnosis of food allergy at the TFAIC, and The Portland Hospital.

Professor Du Toit is renowned for his clinical research, having conducted landmark trials into the prevention and treatment of food allergies. He has served as Investigator on trials that have led to the licensing of Palforzia, and the development of the EPIT peanut patch.

Recent prestigious international awards include the Hugh A. Sampson Lectureship in Food Allergy at the 2022 AAAAI Annual Meeting, the UK Dept Health and Social Care Advisory Committee on Clinical Excellence Awards (ACCEA) Bronze award in 2021, the Daniel Bovet Award for Allergy Treatment and Prevention by the European Association of Allergy and Clinical Immunology in 2020 and the Dr William Frankland Award for Outstanding Contribution to Allergy by the British Society of Allergy & Clinical Immunology in 2020. 

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