A 25-year-old woman reporting an allergy to penicillin.

The article discusses the case of a 25-year-old pregnant woman with an allergy history. Topics covered include the prescription for intramuscular injections of penicillin G benzathine for latent syphilis, the features of hypersensitivity reactions mediated by immunoglobulin E and the use of skin testing in excluding type 1 reactions to penicillin. Also mentioned is the belief that individuals with penicillin allergy has a risk of hypersensitivity with cephalosporins.