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Experts say using penicillin alternatives can lead to longer stays in hospitals and high costs. Getty Images
  • About 10 percent of people have a penicillin allergy noted on their medical records.
  • Fewer than 1 percent of people are actually allergic to penicillin, according to new research.
  • Penicillin alternatives contribute to longer hospital stays, increased microbial resistance, and higher costs.
  • To determine if you truly have an allergy, speak to an allergist or immunologist.

Penicillin has been a versatile and useful antibiotic ever since it was first synthesized from mold in 1928.

But not everyone can tolerate this family of antibiotics.

About 10 percent of people reportedly have a penicillin allergy listed in their medical records.

While having an allergy to penicillin is indeed possible, new research suggests that the vast majority of people — even those who have a listed penicillin allergy — aren’t actually allergic.

What’s more, the implications shine a light on medical record keeping and microbial resistance.

In a paper published today, researchers from the American College of Allergy, Asthma & Immunology (ACAAI) concluded that medical databases don’t tend to reflect reality when it comes to penicillin.

“The biggest takeaway is that penicillin allergy evaluation is becoming more widespread and patients are being evaluated, as appropriate,” explained Sonam Sani, MD, a doctor of internal medicine in Mineola, New York, the study’s lead author, and an ACAAI member.

“However, despite having negative penicillin testing, some patients still carry their penicillin allergy label in their electronic medical record and pharmacy records,” Sani told Healthline. “Some patients are still hesitant to take further penicillins if prescribed and these are all barriers that we as allergists face and need to work together to overcome.”

It’s been common knowledge for some time that true penicillin allergies are not as common as medical records might suggest.

The Centers for Disease Control and Prevention (CDC) states that fewer than 1 percent of the population is truly allergic to penicillins.

The agency adds that about 80 percent of patients with a penicillin allergy will lose their sensitivity over time.

A 2015 study concluded that serious penicillin allergies only occur in roughly 0.03 percent of the population.

Blanka Kaplan, MD, who specializes in adult and pediatric allergy, asthma, and clinical immunology at Northwell Health in New York, told Healthline that allergies to penicillin are still overdiagnosed.

“In general, more than 10 percent of people have a label of penicillin allergy, but the truth is that it’s probably no more than 2 percent or so who are truly allergic, and maybe even less,” she said. “That’s why there’s been a move toward de-labeling people with a penicillin allergy.”

If actual penicillin allergies are so rare, why are they so highly reported?

Kaplan says it often goes back to a family history or a reaction during childhood.

“Let’s say a child has an ear infection, so they get prescribed amoxicillin, which is a common antibiotic,” she said. “On day 3, 4, 5 — maybe even 10 — after finishing their prescription, they may get a rash. If a person has a rash in close proximity to taking penicillin, they can get diagnosed with having a penicillin allergy.”

Once such an allergy is on a person’s medical records, it often stays there.

Kaplan says she regularly sees people in their 80s and 90s with a listed penicillin allergy.

“For a young kid who’s on a course of amoxicillin and develops a rash a few days into the treatment, studies have shown that if they’re rechallenged with amoxicillin, the majority won’t react,” she said.

Penicillin is hardly the only antibiotic in a doctor’s arsenal, so there are other options for people with a penicillin allergy.

The problem is that broad-spectrum antibiotics, which are typically prescribed instead, carry a host of issues.

“Such antibiotics have been shown to have adverse effects, such as increasing the risk for developing microbial-resistant infections and has contributed to increased length of stays during hospitalizations,” Sani told Healthline. “In addition, patients are often given more costly alternative antibiotics, which has contributed to increased healthcare costs.”

These broad-spectrum antibiotics are also stronger.

This means that treating an infection with them is like using a blunt instrument, whereas penicillin is more of a fine tool.

Things would be much smoother for doctors and their patients if medical records were standardized and centralized.

But they’re not.

“There are no universal medical records,” said Kaplan. “If you go to Northwell, all the records are connected. If you go to Mount Sinai [Hospital in New York], they have a different set of records. There’s no universal set of records.”

This can lead to problems when a person’s medical history is scattered across databases from different hospitals and doctors. There’s been work done to improve this, but it’s still an inexact science.

“What we do here is, after we de-label people, we send their primary care doctor a note and I send the patient a note asking them to go to the pharmacy so they can update their records,” said Kaplan.

“I can only change the records that are accessible to me and that’s a problem,” she said. “A lot of times, things get put into it and not removed. That’s an obstacle even after we de-label.”

Both Sani and Kaplan say it’s a good idea for people with listed penicillin allergies to talk to an allergist or immunologist to have their allergy evaluated.

“You should ask if your allergist evaluates for penicillin allergy, as not all practices do,” noted Sani.

Kaplan adds that there’s a test that should determine — once and for all — whether you’re truly allergic. This test is known as a challenge.

“This is when you’re in the doctor’s office and you take a dose of amoxicillin in the office and the doctor observes you,” she explained. “That’s the ultimate test for a penicillin allergy. The gold standard is the amoxicillin challenge, as amoxicillin is a sibling to penicillin.”