What we know about penicillin allergy

Rashes are common in children during childhood illnesses. In some cases, children are told they are allergic to penicillin because they developed a rash whilst on an antibiotic. However, it is thought that in many of these cases, the rash is related to the underlying illness and not the antibiotic. Being labelled penicillin allergic can limit use of necessary antibiotics with any future illness. We know that <10% of children labelled as penicillin allergic are truly allergic and that the ones that are allergic, often lose their allergy after 5-10 years.


What we are not sure about

It is recognised that there are no reliable tests to determine if a child is truly penicillin allergic and the only reliable test is to administer a dose of antibiotic orally which is known as an ‘oral challenge’.


Why is this study being done?

This study is being done to confirm or exclude penicillin allergy in children who have been labelled as penicillin allergic but are thought to be at very low risk of having a true penicillin allergy. In addition, this study will assess if it is feasible (practical) to do this oral challenge in an outpatient (hospital) setting followed by a home course.


What the study involves

Only carefully selected children who are unlikely to have true penicillin allergy and have a history of a skin rash alone on taking penicillin will be invited to complete the study. If the child is deemed at low risk of penicillin allergy, they will be offered an appointment in outpatients in University Hospital Galway to undergo the challenge. No blood or skin tests are performed.

The British Society of Allergy and Clinical Immunology BSACI advises that children without any history of severe allergic disease who have a history of a skin rash whilst taking oral penicillin and are labelled penicillin allergic can safely be tested for penicillin allergy by giving an oral dose of antibiotic. As per BSACI guidelines, a single dose of penicillin is administered orally and the child is observed for 2 hours. If no hypersensitivity reaction occurs, the child is discharged home on a 5-day course of oral penicillin to determine a delayed rash. If there is no reaction, then the label of ‘Penicillin Allergy’ can be removed.

What are the advantages of taking part in this study?

On passing the oral challenge, patients can safely have beta lactam antibiotics in the future.

THIS STUDY IS NOW CLOSED. Thank you to all GP’s, parents and patients who participated.

Where can I get further information?

Please contact:

Dr Hilary Allen (MCRN 222824)

Paediatric Dept., University Hospital Galway.

Phone No: 091-524222