The Importance of Diagnostic Tests in Delayed Type Beta-Lactam Allergy: A Case Report

Adverse reactions to drugs have been defined by the WHO as unwanted effects that occur during the use of a drug. The diagnosis of drug allergies is not always straightforward due to confounding factors such as the use of multiple drugs and similarity of the pertinent symptoms to those that can be attributed to disease processes. In children, drug allergies are most commonly mistaken for rashes induced by viral infections. The first step towards the diagnosis of drug allergies is a detailed history and the second step is choosing a laboratory test according to this history. Skin prick testing is preferred for immediate type reactions while skin patch testing should be performed for delayed type reactions. When allergy tests are negative, drug provocation testing is the gold standard. In this paper, a case with a negative skin patch test that was ultimately diagnosed through a provocation test is presented.