Penicillin Allergy Misdiagnosed in Most Cases

Most people who are told that they are allergic to penicillin are mistakenly diagnosed based on initial reactions instead of a confirmatory test, claims a new study.

Researchers at the University of Texas Southwestern Medical Center (Dallas, TX, USA) examined the medical records of 15 patients who were thought to be penicillin-allergic, who were subsequently tested to confirm their allergy. The researchers found that the patients tested negative, with no adverse drug reactions or evidence of recurrence of their penicillin allergy. All the patients could be treated safely with intravenous penicillin. The study was presented at the annual meeting of the American College of Allergy, Asthma and Immunology, held during November 2015 in San Antonio (TX, USA).

“Anyone who has been told they are penicillin allergic, but who hasn't been tested by an allergist, should be tested,” said lead author Prof. David Khan, MD. “An allergist will work with you to find out if you're truly allergic to penicillin, and to determine what your options are for treatment if you are. If you're not, you'll be able to use medications that are safer, often more effective, and less expensive.”

“Recent research has shown that patients who are labeled penicillin-allergic and take other antibiotics are more likely to have poor outcomes, such as development of colitis, longer hospital stays, and greater numbers of antibiotic-resistant infections,” said meeting presenter allergist Roland Solensky, MD, of the Corvallis Clinic (Corvallis, OR, USA). “There has been a push to be more proactive and evaluate patients with history of penicillin allergy even when they’re well and not in need of an antibiotic. The vast majority turn out not to be allergic and can be treated with penicillin.”

Penicillin side effects that include nausea and vomiting, mild diarrhea, or headache commonly occur while taking the drug, but do not herald an allergic reaction or are considered dangerous enough to halt continued drug use. Mistaking side effects for allergic reaction leads to penicillin allergies being incorrectly reported by patients about 90% of the time, making it more difficult for doctors to treat infections.

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University of Texas Southwestern Medical Center