Type IV allergy to amide-type local anesthetics

The case of a 45-year-old woman is reported, who developed intense erythema and itching 1 day after subcutaneous (s.c.) injection of a local anesthetic containing mepivacaine and methylparaben. The reaction was attributed to a delayed-type sensitivity to mepivacaine, since mepivacaine gave a positive patch test response and also elicited a delayed sensitivity reaction after s.c. challenges, whereas prick and patch tests with methylparaben, as well as oral challenges, were negative. Interestingly, the patient also showed sensitization to lidocaine, a compound to which she had previously also been exposed.