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Cephalosporin Penicillin Allergy — ORE Part 1 MCQ

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HardPharmacology & TherapeuticsCephalosporin Penicillin AllergyORE Part 1

A patient reports a non-immediate, non-severe maculopapular rash after a previous course of penicillin. They now have a dentoalveolar abscess with spreading cellulitis for which antibiotic treatment is indicated in addition to urgent drainage. Which statement best reflects current UK prescribing information for cefalexin?

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Reveal the answer and explanation

Correct answer: B — It may be prescribed cautiously after checking the allergy history

**A is correct.** A remote non-immediate, non-severe rash is not itself a listed contraindication to cefalexin. The UK SmPC contraindicates cefalexin in patients allergic to cephalosporins, but advises caution in penicillin-sensitive patients because partial cross-allergenicity and severe reactions have been reported. Therefore, the prescriber should clarify the previous reaction and only use cefalexin after weighing suitability and alternatives; urgent drainage and assessment of severity remain essential in a spreading odontogenic infection. **B** is wrong because penicillin allergy does not create an absolute cefalexin contraindication. **C** is wrong: the SmPC does not establish cefalexin as the preferred dental alternative. **D** is wrong because the nature and timing of the prior reaction materially affect risk. **E** reverses the risk principle: previous immediate or severe reactions warrant greater avoidance and caution, not selection of cefalexin.

Reference: Electronic Medicines Compendium. Cefalexin 500mg Capsules – Summary of Product Characteristics, sections 4.3–4.4 (updated 20 September 2024). https://www.medicines.org.uk/emc/product/554/smpc