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Most People Who Believe They Have This Common Allergy Actually Don't

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Millions of people in the US who have a documented penicillin allergy on their medical record may not actually be allergic. These individuals are often foregoing the best, safest, and most cost-effective option for alternatives that can cause unnecessary complications, according to a new report published in JAMA.

The researchers are now advising patients with penicillin allergy to consult their doctors to reassess whether their allergy is truly present. A 2017 review of 24 studies found that 95 percent of patients tested negative for penicillin allergy and instead could be treated safely with the antibiotic. 


The recent review is a collaboration among physicians and three medical boards based on evidence gathered over the years. They now suggest revisions to how penicillin allergies are evaluated and diagnosed. 

"Many reported penicillin allergies are established during childhood, when it is by far the most commonly prescribed antibiotic,” said lead and corresponding author Erica Shenoy of MGH Division of Infectious Diseases in a statement. “If penicillin is prescribed for what is actually a viral rather than a bacterial infection, a rash that develops may be caused by the virus but attributed to a penicillin allergy, which then is documented in the patient's chart and never questioned again.”

This can lead to patients not receiving penicillins or related drugs, even when it is the best treatment option available to them. Not only that but alternatives can also lead to an increased risk of infections like C. difficile and methicillin-resistant Staphylococcus aureus (MRSA).

This all is not to say that penicillin allergies don’t exist – they do. Patients truly allergic can develop hives, shortness of breath, wheezing, anaphylaxis, and other life-threatening reactions. The validity of the allergy is not in question but the quality of screening is. The team believes the allergy is too broadly applied in the US, with around 10 percent of Americans reportedly allergic.


“If I had my way, verification of a penicillin allergy would be on many of our checklists, just like age-related screenings and immunizations,” said Shenoy. “Evaluating a reported penicillin allergy, regardless of the current need for an antibiotic, can lead to really important benefits for our patients.”

Senior author Kimberly Blumenthal added that it's her hope that parents of children with penicillin allergy are aware that the label may not be correct and they can be evaluated further. Such a follow-up may involve allergy skin testing, monitored by a doctor, ideally when the patient is healthy. Please do not test your penicillin allergy by yourself. 

“If such allergies are routinely evaluated, patients will not needlessly avoid the beta-lactams that may be the best treatment for their infection and reduce the development of antibiotic resistance,” said Blumenthal.

The review was carried out by physicians at Massachusetts General Hospital, Kaiser Permanent, and Northwestern Medicine at Northwestern University. The three boards involved include the American Academy of Allergy, Asthma, and Immunology, the Infectious Diseases Society of America, and the Society for Healthcare Epidemiology of America. 


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