A Simple Way to Determine if a Patient Is Really Allergic to Penicillin

BOSTON – Patients with a penicillin allergy may be delabeled based on methods that don’t require specialist intervention or other more resource-intensive testing, a researcher reported.

In a quality-improvement project at a community hospital, 56 inpatients had an allergy to penicillin listed in their electronic health records (EHR), and 38 were delabeled based either on medical history (nonallergic reaction or previous penicillin exposure) or via an oral challenge without skin testing, explained Ibrahim Shah, MD, of the Indiana University School of Medicine in Indianapolis.

There was one patient who had nausea/vomiting and failed the challenge and six who qualified for the challenge but did not get it. Of the latter, five refused the challenge and one had acute interstitial nephritis where penicillin is contraindicated, he stated in a poster presentation at the IDWeek annual meeting.

Overall, Shah reported a “95% rate of oral challenge and a 67% delabeling rate.”

But the results did necessarily hold up over the long term: Shah also reported that 7 months later, 13% had the penicillin allergy label re-added to their EHRs, although that finding aligns with “current literature [that] indicates that 12%-50% of patients retain a penicillin allergy label in their [EHR] after a successful delabeling,” he said.

He concluded that delabeling inpatients with the approach used in the study was effective, carried little risk, and required minimal resources because consult with an allergist or infectious disease specialist was not required.

He explained to MedPage Today that “about 15% of patients who are hospitalized have penicillin allergy notes in their medical records, but we believe that as many as 90% of them are not truly allergic.”

“A child may get a penicillin allergy label when he or she develops a rash after penicillin and/or other medications are administered,” he said. “But that rash is usually mild and may be caused by something other than penicillin. Even if it was caused by penicillin, the reaction is usually outgrown by the time the child reaches adulthood, yet the label remains.”

In terms of resources, Shah pointed out that, historically “penicillin allergies were delabeled by allergists or infectious disease specialist. Pharmacy-led delabeling programs are emerging but are limited due to pharmacists not having provider status in all states.”

He reported that 18 of the patients were directly delabeled with a medical history and, in some cases, had no history of being given penicillin. Also, 27 patients were deemed low risk or very low risk for penicillin allergy, while 10 were medium risk, and one was high risk based on the PENFAST, a penicillin allergy decision tool. Only the low-risk and very low-risk patients moved on to oral challenges, he said.

“Historically, penicillin allergy delabeling was done via skin testing followed by a confirmatory oral challenge,” Shah explained. “Such practice is resource heavy and not available at all centers. Our current data claim that it is safe and effective to directly perform oral challenges in low-risk patients.”

The research by Shah and colleagues, including residents at the hospital, was done from April 2022 to June 2022.

Werner Bischoff, MD, PhD, of Wake Forest University School of Medicine in Winston-Salem, North Carolina, noted that “there are medical consequences to being labeled with a penicillin allergy.”

He told MedPage Today that “people who have a label of penicillin allergy have limited options for antibiotic treatment, and that can sometimes be life-threatening.”

Bischoff, who was not involved in the current study, explained that “we have a similar program to [the study] in Indiana. We attempt to confirm that these people really are allergic to penicillin. We do know that very few of the people with the label are really allergic to the drugs.”

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