Adverse reactions to β-lactam antimicrobials

Beta-lactam antibiotics are among the most clinically useful antimicrobials used in medicine. Unfortunately, adverse events related to their use remain poorly understood by many clinicians and, in particular, the misdiagnosis of β-lactam allergy and misunderstanding of crossreactivity among members of the β-lactam antibiotics may effectively eliminate a whole class of antimicrobials from use and require the use of broader spectrum agents with less well-established safety profiles.

This review describes the range, diagnosis and management of adverse events associated with β-lactam antimicrobials, particularly focusing on recognition, diagnosis and management of true allergy and risk of cross-sensitivity between β-lactam antibiotics. A literature review was undertaken using PubMed, focusing primarily on literature published in the past 10 years relating to β-lactam adverse events and allergy.

Beta-lactams are generally safe drugs and serious adverse events are rare and allergy is overdiagnosed. Accurate diagnosis can usually be achieved through careful history and in some instances skin or in vitro testing is required. Even among individuals with true immediate-type allergy to penicillin, most cephalosporins are readily tolerated and desensitization is usually an option in cases where no alternate antimicrobials are available. Other allergic reactions (Type II, III and IV) are rare and avoidance of the culprit agent is generally recommended. Nonallergic or morbilliform rashes are generally not allergic in nature and should not prompt drug or class avoidance. Other adverse events are frequently dose-related and can be avoided by appropriate dosing and consideration of renal function.