Clinical Question

Is an amoxicillin oral provocation challenge safe and accessible for distinguishing an erroneous penicillin allergy from a true one in adults and children?

Bottom Line

The study reported that the outcome of an amoxicillin oral provocation challenge—conducted in 99 adults and children who were initially labeled as having a penicillin allergy—subsequently identified the participants by history to be at low risk of having a true allergy. A total of 96 patients (97%) completed an amoxicillin oral provocation challenge with no reaction, which resulted in the removal of an erroneous penicillin allergy label. The three patients who had an allergic reaction had mild symptoms and required minimal intervention (i.e., no epinephrine). Use of this method to identify the millions of adults and children who have been incorrectly labeled as having a penicillin allergy may result in significant health care savings by eliminating the use of alternative antibiotics that are less effective and safe and more expensive. (Level of Evidence = 2b)

Synopsis

Although approximately 10% of adults and children are labeled as having an allergy to penicillin, less than 20% of those are truly allergic. It is not practical to refer the millions of adults who are labeled allergic to penicillin for testing. However, an easy rule is available that can identify adults at low risk of a true penicillin allergy (the adult version is reliably accurate; this is not true when using the same decision rule for children 12 years or younger). The investigators, using similar criteria as those in the PEN-FAST decision tool, identified 99 adults and children, 18 months or older, who were considered low risk (less than 5%) for having a true penicillin allergy. Clinical settings were equipped with oral diphenhydramine elixir to manage mild reactions and epinephrine to manage anaphylactic reactions. Amoxicillin was given as an oral suspension (250 mg per 5 mL). The first 10% of the challenge dose (50 mg, or 4.5 mg per kg if the patient weighed less than 10 kg [22 lb]) was given, and the patients were observed for 20 minutes. If no reaction occurred, patients received the remaining 90% of the calculated dose (450 mg, or 40.5 mg per kg) and were observed for one hour. A positive reaction was the development of objective findings, including urticaria, wheezing, or swelling, and did not include subjective symptoms such as pruritus without skin changes or dizziness. Patients were instructed to report any delayed symptoms of rash, hives, wheezing, or swelling up to a week later.