Full-course drug challenge test in the diagnosis of delayed allergic reactions to penicillin
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Updated: Jun 4, 2026

Basophil Activation Test for Allergy Diagnosis
Published on: May 31, 2021
Jakob E Borch1, Carsten Bindslev-Jensen
1Department of Dermatology, Odense University Hospital, Odense, Denmark. science@skonvirke.dk
Background:
Drug challenge test (DCT) has long been the most sensitive test in the allergological work-up when investigating for penicillin allergy.
Objective:
To improve sensitivity of the diagnostic work-up in diagnosing penicillin allergics with histories of allergic reactions on day 2 or later in the course of penicillin treatment.
Methods:
A full-course DCT was added to the current protocol if specific IgE, skin tests and DCT were all negative in patients who had a nonimmediate reaction to penicillin treatment. Sixteen patients with a history of an immediate reaction to penicillin treatment underwent testing with negative outcomes.
Results:
Fifty percent of patients undergoing full-course DCT experienced a cutaneous adverse drug reaction. None of the controls reacted (p = 0.001). The mean time of reaction was 6 days. Penicillin V accounted for most reactions. Urticaria was the most frequent clinical reaction observed.
Conclusions:
Full-course DCT offers an improvement of sensitivity and predictive values of the diagnostic work-up of allergic reactions to penicillin occurring on day 2 of penicillin treatment or later.
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