Approach to Introducing Antibiotics in Patients with Possible Allergy

Risk Assessment to Determine Allergy Status

An antibiotic allergy label can be removed without allergy testing when the culprit drug has been used since the index reaction without allergic symptoms, the allergy label was based solely on family history or fear of allergy, reported symptoms are not compatible with an allergic reaction, there was no temporal association between exposure and symptom onset, the index reaction was not severe, confined to the skin, and occurred in remote childhood, or the patient cannot recall any details of the reported reaction 1, 2, 3

For non-severe immediate-type reactions >5 years ago, patients can receive the culprit β-lactam antibiotic in a controlled setting or other β-lactams with dissimilar side chains without prior testing 1, 3, 4
For non-severe immediate-type reactions ≤5 years ago or severe reactions, formal allergy work-up is recommended before re-exposure, and if formal allergy testing is unavailable, re-exposure could be considered in a controlled setting with emergency resources available 1, 3, 4
For non-severe delayed-type reactions >1 year ago, patients can receive the culprit β-lactam antibiotic without formal allergy testing or other β-lactams with dissimilar side chains 1, 3, 4
For severe delayed-type reactions, avoid re-exposure to the culprit drug regardless of timing, and in absence of alternatives, discuss in a multidisciplinary team 1, 3, 5

For cephalosporin allergy, avoid other cephalosporins with similar side chains, and ceftazidime, cefiderocol, and aztreonam share an identical side chain (higher cross-reactivity risk) 4, 5
For non-β-lactam antibiotics, avoid re-exposure to the culprit non-β-lactam antibiotic and others within the same class when the index reaction was severe, and for non-severe reactions, the culprit and other antibiotics within the same class can be reintroduced in a controlled setting 7

In a controlled setting, patient must be observed by trained personnel, emergency treatment for allergic reactions must be readily available, and clear documentation of antibiotic tolerance should be communicated to other healthcare providers 4, 5