Diagnosis of immediate allergy to penicillin: Pilot study

Abstract

Background. Penicillin constitutes the first cause self-reported by patients in drug allergy, the false label of "allergy" to this group of drugs negatively affects the patient's quality of life and medical care.

Objectives.  To confirm the presence of allergy to penicillin and amoxicillin by in vivo exposure tests in patients with a history of immediate reaction to these drugs.

Methodology.  Observational, cross-sectional, descriptive and prolective study. Patients between 12 and 60 years old with a history of immediate reaction after administration of penicillin and/or amoxicillin were included. Skin prick and intradermal tests were performed with benzylpenicilloyl polylysine and penicillin G, as well as oral challenge with amoxicillin.

Results.  Ten female and 3 male patients were included.  The mean age was 39 years. In 84.6% of the cases the last adverse drug reaction occurred 10 years ago and in all cases it manifested with urticaria. Allergy to penicillin was corroborated in only 38.4% of cases. The most frequent adverse reaction after in vivo exposure tests was pruritus in 23%.

Discussion. The majority of patients with self-reported penicillin allergy were not truly allergic, supporting the findings of other studies with similar methodology.

Conclusions. Patients with suspected penicillin allergy should be evaluated by in vivo exposure testing with major and minor determinants to corroborate or rule out allergic reactions and improve treatment conditions.