A new prescription is presented for 'cephalexin 500 mg PO TID x 7 days'. The patient's profile shows a penicillin allergy noted as 'rash, hives'. The patient states she took penicillin as a child and experienced a red, itchy rash. What is the most appropriate action for the pharmacist?

Question: A new prescription is presented for 'cephalexin 500 mg PO TID x 7 days'. The patient's profile shows a penicillin allergy noted as 'rash, hives'. The patient states she took penicillin as a child and experienced a red, itchy rash. What is the most appropriate action for the pharmacist?

Answer options:

• Advise the patient that cephalexin is unsafe due to her penicillin allergy and contact the prescriber for an alternative.
• Dispense cephalexin and counsel the patient to monitor for an allergic reaction, as cross-reactivity is low.
• Recommend administering an antihistamine concomitantly to mitigate any potential allergic reaction. ✅ Contact the prescriber to confirm the indication and discuss the allergy history, potentially recommending a non-beta-lactam antibiotic.

Correct answer: Contact the prescriber to confirm the indication and discuss the allergy history, potentially recommending a non-beta-lactam antibiotic.

Explanation: Although the risk of cross-reactivity between penicillins and first-generation cephalosporins (like cephalexin) is low, it is not zero. Given the patient's childhood reaction, it is prudent for the pharmacist to contact the prescriber to discuss the allergy details and explore alternative antibiotics, especially a non-beta-lactam, to ensure patient safety.