Drug allergy de-labelling with a direct oral challenge in outpatient hospital visits

Although oral direct challenge has been adopted by numerous clinicians around the world in a context of drug hypersensitivity, drug allergy de-labelling remains largely confined to hospital-based care and mostly for penicillins In this study, we aim to perform direct oral drug challenge (DODC) in patients with low-risk allergy to drugs (not only penicillin) in outpatient visits. We conducted a prospective single-centre study from May 2022 to January 2024. Inclusion criteria were age ≥14 years and a label of drug allergy with an initial reaction compatible with an allergic reaction. Exclusion criteria were severe anaphylaxis or severe cutaneous adverse drug reactions or prior skin tests to the suspected drug. The culprit drug was given as a standard single dose in an outpatient hospital visit. In total, 304 patients were included. Penicillins were the most frequent culprit drugs with 228 (75%) patients. The other drugs involved in allergy labelling were as follows: nonsteroidal anti-inflammatory drugs (NSAIDs) in 31 (10.2%) patients, cephalosporins in 10 (3.3%) patients, other antibiotics in 15 (4.9%) patients, analgesics in 7 (2.3%) patients and corticosteroids in 4 (1.3%) patients. Nine (3.0%) patients had a reaction with other drugs. Among the whole cohort, 295 (97.0%) had no reaction during DODC. Ten patients presented a mild reaction including three patients with an immediate reaction and six with a delayed reaction. In conclusion, allergy de-labelling to all drugs in patients with low-risk allergies can be safely conducted in outpatient visits.