Objective: To examine whether oral challenge with penicillin for patients with a known history of non-life threatening allergic reaction to penicillin is well-tolerated irrespective of skin-testing results long after the event occurred.~Methods: In this prospective, open-label, controlled, multi-clinical trial, 8702 individuals from primary care clinics were screened for penicillin allergy. 169 patients with a history of non-life threatening allergic reaction to penicillin, dating back at least 3 years, were recruited for study. Regardless of the response to penicillin skin testing, patients received the recommended daily dosage of penicillin and amoxicillin on two separate occasions. 2-6 years later a follow-up was conducted to assess the outcomes of further penicillin administration.~Results: 92.9% of the patients had an allergic reaction 6 years or longer before enrollment in the study. Of 272 challenges, 137 were skin-test positive with mild rash in 9 patients (6.6%), and 135 were skin-test negative with similar allergic reaction in 5 (3.7%) (P =.29). At follow-up, 3 of 55 patients (5.5%) who were given a full treatment course of penicillin developed mild skin eruption.~Conclusions: A positive penicillin skin testing of patients with a history of non-life threatening allergic reaction to penicillin occurring 3 years or longer from the event was not associated with a greater prevalence of adverse reactions to oral challenge with penicillin than a negative one. It is of importance to determine whether oral challenge can serve as a diagnostic procedure for this particular group of patients, thereby saving the need for prior penicillin skin testing.
The purpose of this study is to examine whether oral challenge with penicillin for patients with a known history of non-life threatening allergic reaction to penicillin is well-tolerated irrespective of skin-testing results