The Safety and Accuracy of Drug Patch Testing in Delayed Hypersensitivity Reactions

Purpose of ReviewAdverse drug reactions are common in both the inpatient and outpatient settings and lead to limitations in future treatment options. Patch testing, used in conjunction with clinical history and the reaction phenotype, can help to improve identification of the culprit medication and evidence for its use is growing. Here we discuss a standardized approach to patch testing which can lead to accurate and reproducible results.Recent FindingsAlthough patch testing may have low sensitivity, specificity is generally high with good utility depending on reaction phenotype and implicated medication. Patch testing has the highest sensitivity for acute generalized exanthematous pustulosis and drug reaction with eosinophilia and systemic symptoms and at the site of fixed drug eruptions. It has the lowest sensitivity in Stevens-Johnson/toxic epidermal necrolysis.SummaryPatch testing, used in conjunction with clinical history, can help to improve identification of the culprit medication depending on reaction phenotype. Overall, it is safe to perform patch testing with rare risk of reactivation of primary reaction.