Most patients who report having a penicillin allergy are not really allergic to the antibiotic, and they may be missing out on the best treatment for their condition as a result, according to a report in the Journal of the American Medical Association.

Although one in 10 patients has a penicillin allergy noted in their medical record, many have been misdiagnosed as children or are no longer allergic, the authors write.

Dr Erica Shenoy of Massachusetts General Hospital in Boston, coauthor of the report, says about 95% of those in the US with a recorded penicillin allergy don’t truly have the allergy.

“The ‘penicillin allergy’ label affects the antibiotic options available to patients, resulting in the use of alternative and often less effective antibiotics that can expose patients to unnecessary risks,” Dr Shenoy says.