Tag: R1 side chain

The historical belief that approximately 10% of patients with a penicillin allergy would also be allergic to cephalosporins is considered a medical myth by modern evidence. In reality, the answer to the question, *do cephalosporins have cross allergy*, is far more nuanced, depending largely on chemical structure and the generation of the drug.

Approximately 10% of the U.S. population reports a penicillin allergy, often leading to concerns about what medication has a cross allergy with cefazolin, a related cephalosporin antibiotic [1.7.5, 1.3.6]. However, recent data shows the actual cross-reactivity is much lower than historically believed [1.4.3].