by Deb Balzer, Mayo Clinic News Network

Chemical structure of Penicillin G. The sulfur and nitrogen of the five-membered thiazolidine ring are shown in yellow and blue respectively. The image shows that the thiazolidine ring and fused four-membered β-lactam are not in the same plane. Credit: Public Domain

Penicillin belongs to a group of antibiotics used by health care professionals to combat a wide array of bacterial infections, including strep throat, ear infections and pneumonia. Penicillin, one of the most widely prescribed antibiotics, is also one of the most frequently reported medication allergies.

The Centers for Disease Control and Prevention says 10% of people living in the U.S. report having a penicillin allergy. However, less than 1% are truly allergic.

Dr. Nipunie Rajapakse, a pediatric infectious diseases physician with the Mayo Clinic Children's Center, says if your health care team can't prescribe the preferred antibiotic for your bacterial infection due to a listed allergy, it can pose additional risks to your health.

Reconsidering penicillin allergies

Penicillin is one of the most prescribed antibiotics for bacterial infections.

"And the best treatments for things like strep throat, ear infections, pneumonia are penicillin or another antibiotic in that same family," says Dr. Rajapakse.

She says if your medical chart indicates a penicillin allergy, your health care team needs to look for other options.

"We know that these other antibiotics are often not as effective as a penicillin. So that means you might not get better," Dr. Rajapakse says.

And they can be harder on your system. She says people often misinterpret side effects of the medication as symptoms of an allergy.

"Symptoms of a true antibiotic allergy are things like hives,rash, so usually a very itchy kind of raised rash that can develop," she says.

It's estimated 50% of people will outgrow the allergy within five years.

"Even if you did have a reaction in the past, it's important to discuss this with your primary care provider. And if it's been enough years out, you may be eligible for testing and to have that allergy removed from your chart," says Dr. Rajapakse.

Testing for penicillin allergy

Talk with your health care team to find out if you need to be tested for a penicillin allergy. Penicillin skin testing and oral challenge doses are reliable methods for evaluating a penicillin allergy.

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