Patch Testing in the Diagnosis of Medication Allergy

In evaluation of medication allergy, the utility of drug patch testing is dependent on both the type of drug reaction and the suspected causal drug. Epicutaneous patch tests reproduce T cell-mediated delayed hypersensitivity; thus, eruptions at least partially mediated by T cells can be confirmed by positive drug patch test (DPT) responses in some patients. These include acute generalized exanthematous pustulosis (AGEP), drug reaction with eosinophilia and systemic symptoms (DRESS), fixed drug eruptions (FDE), macular drug reactions (Bmorbilliform^ or Bexanthematous^ reactions), and Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN). Currently, literature supports that specific drugs, including antiepileptics and certain antibiotics, are most likely to produce diagnostic patch test results. However, drug patch testing cannot be used reliably for all medications. We suggest that standardized international guidelines should be developed and implemented to improve the comparability of results from drug patch testing reported in literature. Furthermore, an organized, systematic research strategy should be executed in order to gain further understanding of how and when drug patch testing can be used most effectively.