Safety and Outcomes of Oral Graded Challenges to Amoxicillin without Prior Skin Testing

Publication date: Available online 23 May 2018
Source:The Journal of Allergy and Clinical Immunology: In Practice
Author(s): Melissa Iammatteo, Santiago Alvarez Arango, Denisa Ferastraoaru, Nadeem Akbar, Andrew Y. Lee, Hillel W. Cohen, Elina Jerschow
BackgroundUnconfirmed penicillin allergy poses substantial public health consequences. The most widely accepted protocol to evaluate penicillin allergy is skin testing followed by amoxicillin challenge.ObjectiveTo evaluate the safety of direct oral graded challenges to amoxicillin.MethodsProspective single-blind clinical trial with historical controls of patients ≥ 7 years old with historical non-life-threatening reactions to penicillin. Patients received placebo followed by a 2-step graded challenge to amoxicillin. The allergic reaction rate was compared to the rate observed in our previous study that included skin testing and to the currently reported penicillin allergy prevalence in the US population.ResultsOf the 155 participants who completed an amoxicillin challenge, 120 patients (77.4%) experienced no reaction while 31 patients (20%) experienced non-allergic reactions to either placebo (n=16) or amoxicillin (n=15). Four patients (2.6%) developed mild allergic reactions. Significantly (p=0.03) fewer patients [4/155, 2.6%, 95% CI (1.0%, 6.5%)] were determined to be allergic compared to 14/170 subjects [(8.2%, 95% CI (5.0%, 13.4%)] in our previous study where patients were determined to be allergic based on either positive skin tests (n=11) or allergic challenge reactions after negative skin tests (n=3). This 2.6% reaction rate was also significantly less than the 10% reported US prevalence of penicillin allergy (p=0.003).ConclusionsPlacebo-controlled oral graded challenges to amoxicillin without prior skin testing may be safe for patients ≥ 7 years old with non-life-threatening historical reactions to penicillin. Amoxicillin can be tolerated by the majority of patients with self-reported penicillin allergy.