Patients who say they're allergic to penicillin are usually wrong

More than 32 million people in the U.S. have reported penicillin allergies -- about 10% of the population. But almost 95% of them are not penicillin-allergic, and are removing themselves from eligibility for ideal antibiotic treatments, according to a review in JAMA.

"More than 1 in 10 people who seek medical care self-report a history of penicillin allergy," David Lang, MD, president elect of the American Academy of Allergy, Asthma and Immunology (AAAAI), said in a statement. "Recent evidence has confirmed most patients with unverified penicillin allergy are needlessly avoiding penicillins."

The AAAAI, Infectious Diseases Society of America (IDSA), and the Society for Healthcare Epidemiology of America collaborated in writing the new recommendations to provide physicians with tools to help identify patients who can safely be treated with penicillin despite their reported reactions.

A detailed history of past reactions to penicillin can allow a physician to confidently eliminate the allergy in some cases. Many reactions can be identified as non-allergic (diarrhea, headache, nausea, abdominal pain), and these patients are considered low risk. Patients with an isolated history of itching without rash are also considered at low risk. Patients classified as being at low risk should be considered eligible for treatment with penicillins, without referral to an allergist, the authors advise.

Unfortunately, many patients only say "rash" or "swelling", or recall being told of the allergy by a parent, none of which allow the confident elimination of anaphylaxis as a risk from re-treatment with penicillin.

More concerning reactions are urticaria or other itchy rashes, or those with allergic-appearing reactions. These patients are considered at moderate risk.

Even in high risk patients (those with repeated reactions to penicillins, or with a history of anaphylaxis), desensitization can be pursued in the hospital if penicillin treatment is required immediately for optimal antimicrobial coverage. This scenario is rare, as alternative broad spectrum non-beta-lactam antibiotics (e.g., fluoroquinolones, aztreonam) are available. Cephalosporins or carbapenems can also be used, although with some risk of cross-reactivity in pencillin-allergic patients.

For the vast majority of patients, the mistaken allergy will have no consequences. For the few who experience life-threatening infections (sepsis), their listed allergy can result in their receiving suboptimal antibiotic treatment.

JAMA provided an infographic for clinicians to show patients to help them understand penicillin allergy and buy-in to possible use of penicillins despite their allergy history.

Source: JAMA