CIDRAP-Think you have a penicillin allergy? You probably don’t

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Think you have a penicillin allergy? You probably don’t

www.cidrap.umn.edu

Think you have a penicillin allergy? You probably don’t​

Liz Szabo, MA

Today at 1:50 p.m.
Antimicrobial Stewardship


Heather Millington suffers frequent bouts of bronchitis and pneumonia, caused by a weak immune system and what she calls “an alphabet soup” of chronic conditions.

“When I get sick, it tends to really knock me down,” said Millington, 35, who lives in Indiana and is unable to work because of her health problems. “I feel a lot older than 35 when I get sick.”

Yet Millington told CIDRAP News her doctors have been afraid to prescribe the safest and most effective treatments for her respiratory infections—antibiotics in the penicillin class—because of the possibility that Millington is allergic to them.

Although Millington can’t remember taking penicillin, her parents told her that the antibiotic gave her a rash when she was a baby.

Many of the more than 32 million Americans with reported penicillin allergies have similar stories.

Yet the vast majority of people who think they’re allergic to penicillin could take it safely, after an appropriate evaluation, said Nonie Arora, MD, MBA, an allergist and immunologist at the Michigan Allergy, Asthma and Immunology Center.

Although 10% of Americans believe they’re allergic to penicillin, research shows the actual rate is less than 1%, according to the Centers for Disease Control and Prevention.

That’s partly because most people with penicillin allergies as children end up outgrowing them, Arora said. More than 90% of people with penicillin allergies are no longer allergic 10 years later.

In other cases, people mistakenly believe they’re allergic to penicillin because they experience nausea or diarrhea after taking the drug. But upset stomachs are a side effect of the medication, not an allergic reaction, said Amesh Adalja, MD, an infectious disease physician and senior scholar at the Johns Hopkins Center for Health Security.

“The vast majority of people who are labeled allergic may never have been allergic in the first place,” Arora said.

Alternative antibiotics can pose harm​

Being mislabeled with penicillin allergy is no trivial matter.

When doctors can’t prescribe penicillin, they may have no choice but to provide a second- or third-choice antibiotic that’s less likely to cure the infection but more likely to cause harmful side effects or complications, Arora said.

A study published in 2019 found that people with reported penicillin allergies were 14% more likely to die for any reason than people without penicillin allergies. “Once a penicillin allergy is recorded, patients receive less effective and/or more toxic antibiotics for subsequent infections,” the study authors wrote.

In February, CIDRAP News published the story of Dolores Hernandez Owens, who died after her dentist prescribed a second-choice antibiotic called clindamycin, which carries a high risk of causing devastating intestinal infections with a bacterium called Clostridioides difficile, more commonly known as C diff.

“We see a lot of harm in folks who are labeled as penicillin-allergic and then get alternative antibiotics,” Arora said.

That’s why it’s so important for people with suspected penicillin allergies to undergo definitive testing, said Erinne Kennedy, DMD, MPH, assistant dean for curriculum and integrated learning at Kansas City University College of Dental Medicine in Missouri.

Kennedy routinely recommends that her patients with penicillin allergies get tested by an allergist.

Testing people for penicillin allergies is especially important in hospitals, where about half of patients receive antibiotics. Most hospitals with antibiotic stewardship programs test patients with reported penicillin allergies, Adalja said.

But people don’t have to wait for a referral from their doctor or dentist, Kennedy said.

“If you have a penicillin allergy and you're a patient reading this article, I would encourage you to talk with your primary care doctor to ask about being screened for a true penicillin allergy,” Kennedy said. “It’s really important for us to understand what you're truly allergic to so that we can provide you the safest drug.”

De-labeling to set the record straight​

To be sure, people with reported penicillin allergies shouldn’t dismiss them without seeing a doctor, Arora said. Although true penicillin allergies are rare, they can cause serious and even fatal reactions. Before making any medication changes, she said, people should consult their primary care team.

People who learn that they’re not allergic to penicillin can ask their doctors to help them through the “de-labeling process,” which involves removing the allergy from all of their health records. That could involve contacting not just doctors, but dentists, oral surgeons, pharmacists, and other healthcare providers.

If you have a penicillin allergy and you're a patient reading this article, I would encourage you to talk with your primary care doctor to ask about being screened for a true penicillin allergy.

Multiple medical societies recommend penicillin allergy testing, including the American College of Allergy, Asthma and Immunology, the Infectious Diseases Society of America, and the Society for Healthcare Epidemiology of America.

“There is a push within the allergy and immunology field to try to de-label as many people as we can,” Arora said.

In March, the Society for Maternal-Fetal Medicine published a special statement recommending penicillin allergy testing for pregnant people. Pregnant people may need antibiotics before a Cesarean delivery, or to avoid transmitting group B strep infections to their newborns. Receiving the most appropriate antibiotic is important for both mothers and babies.

“Penicillin allergy testing is crucial,” the statement says. “Mislabeling can lead to less-effective, higher-risk, and more costly antibiotic use—potentially causing worse maternal and neonatal outcomes.”

Direct oral challenges, skin tests can provide answers​

Having a reported penicillin allergy has made treating Millington’s illnesses more difficult.

About 10 years ago, a particularly nasty respiratory infection refused to go away, even after a course of antibiotics, Millington said. It took a second round of medication to finally cure the illness.

Millington said her doctors have been extra cautious about prescribing antibiotics because of a C diff infection in 2017. Although Millington said she probably developed the infection owing to her weak immune system, C diff cases often occur because of antibiotic use.

In May, Millington’s doctor suggested she undergo allergy testing.

Her doctor, Craig Sewell, DO, an allergist and immunologist at Indiana University Health, told her, “‘It would be really nice if we had the whole penicillin class for respiratory infections,’” Millington recalled.

Millington had a low risk of developing a dangerous reaction to penicillin, both because her only symptom was a rash, and because that reaction occurred more than three decades ago, Sewell said.

After checking Millington’s breathing and heart rate, Sewell gave her a small, oral dose of amoxicillin, a drug in the penicillin class.

“They checked on me every 15 to 20 minutes, and I didn’t have any reaction” to the first dose, Millington said. Half an hour later, Millington received a full dose of penicillin. After two more hours without a reaction, Millington said she was allowed to leave.

Sewell advised Millington to be alert to signs of allergic reaction after she went home, noting that reactions, such as rashes, can sometimes break out the day after testing.

“I didn't have any problems,” Millington said. “It was really easy.”

Some people at higher risk for an allergic reaction from penicillin—such as someone who developed a life-threatening condition called anaphylaxis within the past five years—need to be tested in two stages, said Haley Pritchard, MD, associate professor of clinical medicine at the Indiana University School of Medicine.

Doctors typically give these patients a skin test first, said Pritchard, medical director of infection prevention and antimicrobial stewardship at Eskenazi Health in Indianapolis. During these tests, a doctor pricks the skin, exposing it to a tiny amount of penicillin. If patients are allergic, they develop swelling that looks and feels like a mosquito bite.

If patients don’t react to penicillin, they can undergo the type of “oral challenge” that Millington took. Patients who don’t react to an oral dose of penicillin can take that allergy off their medical charts.

Penicillin allergy testing is especially important for people such as Millington, who have weak immune systems, or for those who are elderly, Sewell said.

Giving these patients a second-choice antibiotic for a respiratory infection makes it more likely that their illness will last a long time, which increases their risk of serious complications, such as needing oxygen or being put on a ventilator, Sewell said.

Millington said she’s glad she went through testing.

“I’m pretty excited about it,” Millington said. “It’s a relief.”

Allergy testing can reduce the risk of resistance​

Testing people for penicillin allergies—and de-labeling them—benefits everyone, Sewell said.

Prescribing the most appropriate antibiotic reduces the risk that bacteria will mutate in ways that make them harder or impossible to kill, a condition called antimicrobial resistance, Sewell said.

That’s important, because resistant microbes can spread around a hospital to other patients. Resistant bugs also can spread throughout a community.

Antimicrobial resistance contributes to an estimated 5 million deaths a year around the world, and has been listed by the World Health Organization as one of the top 10 health threats.

“This is certainly a public health issue,” Sewell said.