Answer
It depends on the type and severity of the previous reaction. Cefalexin must not be taken after a cephalosporin allergy, and severe penicillin allergy requires prescriber assessment because cross-reactions can occur.
Sources for this answer
- NHSNHS · NHS medicine guidance
- Cefalexin Tablets 500mg — Current selected SmPCemc · Summary of Product Characteristics
General medicine information. Follow the instructions for your own medicine and speak to a pharmacist or clinician about your individual circumstances.