A patient with a penicillin allergy describes an anaphylactic reaction. Which medication class should be specifically avoided?

• A. Quinolones
• B. Macrolides
• C. Cephalosporins
• D. Tetracyclines

Answer: (C)

When someone has a true anaphylactic reaction to penicillin, the main concern is cross-reactivity with other beta-lactam antibiotics. Cephalosporins are beta-lactams and share structural features with penicillins, so they can provoke a similar IgE-mediated reaction in some patients. To be safe in the setting of an anaphylactic penicillin allergy, cephalosporins should be avoided.

The other classes listed are not beta-lactams, so they don’t carry the same cross-reactivity risk with penicillin allergy. They can be considered as alternatives based on infection type and susceptibility, though each has its own considerations.