Fransson S, Mosbech HF, Elberling J, et al. - Given that delayed reactions to penicillins may be detected via intradermal testing with delayed reading (IDTdr), researchers investigated the proportion of provocation-positive patients testing positive on IDTdr. Participants were 57 patients with a positive drug provocation test (DPT) occurring >2 h post-intake of penicillin V, dicloxacillin, pivampicillin, or amoxicillin. These underwent an IDTdr with penicillin G, amoxicillin, ampicillin, and dicloxacillin. This study also involved 18 patients with negative DPTs with the suspected penicillin (control group). Per findings, inquiring with IDTdr would have detected 25% of patients with a DPT-confirmed allergy with delayed reactions. Targeting subgroups who will test positive on IDTdr is challenging. There existed more patients who tested positive on IDT who had taken oral steroids post-DPT, and this may represent an indication that there is a role of skin reaction severity in skin testing diagnostics. There is a need for evaluating further potential predictors for positivity of IDTdr, such as duration of skin symptoms, in large studies so that the investigations of nonimmediate drug allergic reactions may be optimized.