About Drug Allergies

A drug allergy occurs when the immune system reacts abnormally to a medication. This is different from side effects, such as nausea or diarrhoea, which are predictable, yet unintended symptoms that commonly occur as a result of taking medication.

Many medications can trigger allergic reactions. In children, the most common culprits include:

• Antibiotics (e.g. penicillins)

• Non-steroidal anti-inflammatory medications (NSAIDs), such as ibuprofen (i.e. Nurofen)

• Anaesthetic agents

Symptoms of a drug allergy can range from mild skin rashes to more serious reactions, including anaphylaxis.

Differentiating a true allergic reaction to a medication from expected medication side effects or symptoms of the underlying illness being treated by the medication can be challenging. Research shows that penicillin allergy is incorrectly diagnosed in up to 95% of cases. In cases where a thorough assessment confirms a true drug allergy, the risk of reaction often decreases over time, meaning many patients may safely tolerate the medication again in the future. Getting the diagnosis right initially and reassessing the patient's allergy status periodically in the future is essential. For example, being incorrectly labelled with a penicillin allergy limits treatment options, often leading to the use of less effective antibiotics that harbour potential for greater side effects whilst also putting a patient at risk of developing antibiotic-resistant infections.

How Do We Assess or Treat Drug Allergies?

Dr Willcocks provides a thorough evaluation to determine the likelihood of a true medication allergy. Depending on the child’s history, she may recommend:

• Skin or pathology testing

• Supervised oral challenge testing to confirm or safely exclude (“de‑label”) a suspected allergy

This approach helps ensure any unnecessary long-term allergy labels are avoided, ensuring children receive the most effective and appropriate treatments when required in the future. Additionally, in the event a drug allergy is confirmed following comprehensive assessment, Dr Willcocks will be able to provide clear guidance on safe medication alternatives.