Before starting cephalosporin therapy, which history is important to elicit due to potential cross-reactivity?

• A. Penicillin allergy
• B. Hypertension
• C. Depression
• D. Drug dependence

Answer: (A)

Cross-reactivity between beta-lactam antibiotics is the reason to ask about penicillin allergy before giving cephalosporins. Penicillins and cephalosporins share a beta-lactam ring, so a true penicillin allergy can signal a risk of an allergic reaction to cephalosporins, particularly if the prior reaction was severe. Eliciting this history helps you assess safety and consider an alternative or a cautious approach if needed. Hypertension, depression, and drug dependence don’t influence this cross-reactivity, so they’re not relevant to the decision about cephalosporin use.