A wooden hand holds a pink snap closure wristband that says, "Penicillin Allergy."
Penicillin allergies are not as common as we’ve been led to believe. (For Spectrum Health Beat)

What if you always thought you were allergic to the antibiotic penicillin—and then found out you weren’t?

It might not sound like a big deal, but there are real benefits to not having a penicillin allergy listed in your medical chart, according to Nicholas Hartog, MD, a specialist in pediatric and adult allergy and immunology with Spectrum Health Medical Group.

Nearly 10 percent of the general population claim to have a penicillin allergy.

The crazy thing is, 90 to 95 percent of these people can actually tolerate penicillin-based drugs very well, Dr. Hartog said. His data comes from a series of national studies allergists have conducted during the past 10 to 15 years.

Penicillin is a class of antibiotic drugs that includes amoxicillin and Augmentin. A penicillin-based antibiotic is the first-line treatment for a variety of bacterial infections, including sinus and ear infections and many cases of pneumonia.

“If you have any contact with a medical system for infections, there’s a good chance a penicillin derivative may be the right drug for you,” Dr. Hartog said.

Penicillin’s benefits

Penicillin is often the right drug because of its many advantages over alternative antibiotics:

  • More effective—Penicillin is a narrow-spectrum drug that targets the bacteria that cause many infections. “It works. Very few bacteria are resistant to it,” Dr. Hartog said. Alternative antibiotics don’t always fight infections as effectively, so they might have to be prescribed more frequently.
  • Lower cost—Penicillin derivatives themselves are cheaper than alternative antibiotics, and the overall cost of care is lower for patients who get penicillin rather than an alternative.
  • Faster recovery—Hospitalized patients who are treated with penicillin have shorter hospital stays than those treated with alternatives.
  • Fewer side effects and complications—Penicillin alternatives are often too strong or too broad for the situation, so they kill more bacteria than necessary. This leads to increased risk of contracting dangerous, resistant infections like MRSA, VRE and C-diff.

Studies show that hospitalized patients have increased rates of resistant infections and other negative outcomes when they have penicillin listed as an allergy, Dr. Hartog said.

Get tested

The rise of antibiotic-resistant bacteria prompted the Obama administration to create a national action plan in 2015 to combat the problem. In response, the American Academy of Allergy, Asthma & Immunology asked its members to begin systematically testing for penicillin allergy in patients who have the allergy listed in their chart.

“If you have any contact with an allergist, we should test,” Dr. Hartog said.

If it turns out that patients with a history of penicillin allergy can actually tolerate it, then this safer, less costly drug becomes an option for them whenever they need it.

Testing has two stages:

  • Skin test—The doctor delivers a small amount of a penicillin derivative through a scratch in the skin and watches for a reaction like redness or a small bump. Then the doctor injects another small amount under the skin and continues to watch for a reaction.
  • Challenge—If the skin testing is negative after a few minutes, there’s a 98 to 99 percent chance that the patient can tolerate penicillin. To be 100 percent sure, the doctor gives the patient an oral challenge—a dose of penicillin by mouth. “If testing is positive at any point, we do say you are still allergic to penicillin,” Dr. Hartog said.

In Spectrum Health’s adult and pediatric allergy and immunology clinics, Dr. Hartog and his colleague Theodore Kelbel, MD, began testing and challenging patients routinely more than a year ago.

Out of more than 100 patients he’s tested, all with a reported penicillin allergy, Dr. Hartog found only one patient who actually has the allergy.

The rest had no reaction when tested. They were falsely labeled, the doctor said.

Still, a lot of patients are nervous about being tested, which is why allergists do the testing in the safe environment of a clinic.

Why the false label?

How can it be that so many people mistakenly believe they have a penicillin allergy? Dr. Hartog outlined two possible reasons:

  • They were allergic to it at one point but have outgrown the allergy. If you take people who had a legitimate reaction to penicillin and retest them 20 years later, Dr. Hartog said, “we know that 80 percent will lose their sensitivity” and will be able to tolerate penicillin later in life.
  • They were never allergic to it but once had a symptom—a rash or vomiting—that they or their doctor associated with taking penicillin, when it was actually a result of simply being ill. “A child will have a virus and be put on amoxicillin, and will then have a rash at the same time,” Dr. Hartog said. “It’s often hard to know whether that rash was from the penicillin or whether that rash was from the virus.” Hence, a misdiagnosis.

Drs. Hartog and Kelbel are strong advocates of systematic testing, because they see getting more patients off alternative antibiotics as a way to improve the quality of care throughout the health care system. There is even a National Penicillin Allergy Day that aims to increase awareness about this issue.

“I talk to patients about all the benefits we have from (testing),” Dr. Hartog said, noting that this message is especially relevant for older patients and those with chronic illnesses such as cystic fibrosis and immunodeficiency.

For these patients, he said, “it’s not if they’ll get their next antibiotic, it’s when. They’ll see a more direct benefit immediately.”