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Quick and simple test can rule out penicillin allergy
Penicillin is often a better option
If your patients tell you they are allergic to penicillin, would you take their word for it? In fact, the vast majority of patients who say they are allergic to penicillin, — a surprising 91% — actually aren't, according to new research.1 Out of 150 participants who self-reported a penicillin allergy at the University Hospital in Cincinnati, 137 displayed false-positives.
"Only 10% of self-reported penicillin allergies are really accurate," says Joseph Moellman, MD, one of the study's authors and associate professor of emergency medicine at the University of Cincinnati.
The penicillin skin test was formulated by the hospital's Department of Immunology and Allergy and is not yet commercially available, but Moellman says he expects a comparable test to be available soon. During the study, ED nurses did the test and waited for 10 minutes. If the patient didn't react, they waited another 10 minutes after a subcutaneous test is applied to determine that the patient was not allergic to penicillin. Testing for penicillin allergy using skin tests in the ED could allow for more appropriate antibiotic selection in some cases, according to Moellman.
Penicillin is less expensive, is clinically effective in combating bacterial infections such as strep, and lessens the use of broad-based antibiotics, which contribute to bacterial resistance, he explains.
Moellman gives the example of a patient with strep throat that reports a penicillin allergy. "If we have to go by their history, the patient is given azithromycin or clindamycin. The cost is a difference of $70, and you may not get the efficacy you want," he says.
If patients report allergy, ask them what happens
If patients report a medication allergy to you, don't stop there; find out what happened when they took the drugs.
"We are all busy in the ED, but when the nurse is doing the medication reconciliation, it's critical for any kind of drug to write down what the reaction was," says Joseph Moellman, MD, associate professor of emergency medicine at the University of Cincinnati.
If patients say they got an itchy rash and their throat closed off, that represents an allergic reaction, he says. On the other hand, if the patients say they get nauseated, that's likely to be a side effect of the medicine or something they were being treated for already, Moellman adds. "That doesn't represent an allergic reaction."
Whether to prescribe penicillin in this case is a "judgment call for the treating physician," he says. "If I got a detailed history and the patient said they developed minor symptoms such as nausea or diarrhea, I may prescribe penicillin," Moellman says. "If the history is vague and they don't know, all bets are off, and I wouldn't take the chance."