Allergic to penicillin? Maybe not

When Neda Frayha was 13 years old, she had a strange reaction after taking penicillin.

“I just remember being at my house and looking down at my legs, and they were itchy and I had red hives all over them,” Frayha said.

From that point on, she had “allergic to penicillin” marked on her medical chart. It followed her through most of her adult life.

About 30 million Americans have this allergy noted in their medical records. For most of them, that means the most commonly prescribed antibiotics are off-limits.

“The first-line choice for most of our very common infections [is] not an option anymore,” said Frayha. “So a person with a penicillin allergy often has to get second-line antibiotics or even much broader-spectrum, more powerful antibiotics that can have lots of very powerful and bad side effects.”

Frayha is a family-medicine doctor now, so she sees the allergy note pop up on many of her patients’ charts.

Her son also got the diagnosis when he developed a red, bumpy rash after taking amoxicillin for an ear infection.

But this time, Frayha decided to investigate the reaction, to find out if he was really allergic to penicillin.

“I don’t want this world of potentially excellent medications to not be available to him for the rest of his life,” Frayha said.

She took him to see an allergist for testing.

“They gave him one pill of amoxicillin — afterwards, he passed the skin test — and he didn’t have a reaction,” Frayha said. “So that label was totally taken off his chart. He is not allergic to penicillin.”

Then Frayha went through the same testing, and she got the same result: negative for penicillin allergy. Researchers are also finding the same result, she said.

“We’ve actually learned in medicine that 95 percent of people who have a reported penicillin allergy are not allergic to penicillin.”

The reaction she had at 13 — that itchy rash — could have been from anything, not just the penicillin, she said. And most people who are actually allergic to penicillin outgrow their allergy in 10 years.

“We often treat that allergy tab as if it’s written in stone, whereas other parts of the [patient’s] chart we’re constantly updating or things are coming off and being added on,” Frayha said. “We should view that allergy tab with that same fluidity.”

When physicians see penicillin allergy on their patients’ charts, she said, they should ask more questions.

“What actually happened? How old were you? In some cases, the reaction really is severe. They might have had their skin slough off of their body,” Frayha said. “That’s serious, and that warrants more of a closer investigation. But if it was that they had hives when they were 13, like me, then we can actually think about sending them for testing and maybe taking that off of their chart.”

People with a reported penicillin allergy take stronger antibiotics for less serious infections. She said that means they later have a higher risk of MRSA, a resistant staph infection; clostridium difficile colitis, or C.diff; and other serious complications that can make a person incredibly sick.

“So it’s not a harmless thing to just kind of linger in your history for years and years.”