Patch Testing in Paediatric Drug Hypersensitivity Reactions: Current Evidence and Clinical Implications.

Drug hypersensitivity reactions (DHRs) are common in children and are diagnostically challenging, with cutaneous manifestations being the most common presentation. Patch testing (PT) is a well-established tool for investigating delayed T-cell-mediated reactions and is widely used in patients with contact dermatitis. However, its role in paediatric DHRs remains unclear. Available data indicate that PT is safe and particularly useful when drug provocation testing is contraindicated, such as in patients with severe cutaneous adverse reactions. However, diagnostic yield varies considerably among drug classes and clinical phenotypes. Sensitivity is generally low for beta-lactam and most non-beta-lactam antibiotics, which limits their standalone value in common exanthematous reactions. Higher positivity rates have been reported for antiepileptic drugs, and PT may help identify the culprit drug and assess its cross-reactivity. However, evidence supporting the use of nonsteroidal anti-inflammatory drugs and paracetamol remains scarce. Methodological heterogeneity and limited paediatric-specific data further constrain this interpretation. Overall, PT should be considered as a complementary diagnostic tool integrated with clinical history and other tests, highlighting the need for standardized protocols and prospective paediatric studies.