Allergic to penicillin? There’s a 90% chance that’s not true

It’s scary to get an infection during pregnancy. It’s even worse if a patient believes she’s allergic to the best drug to treat it.

But that’s the case for an estimated 10% of the U.S. population who have been told they’re allergic to penicillin. However, more than 90% of these patients are not truly allergic and are wrongly labeled “penicillin-allergic” in their medical records.

This is a serious health concern for all patients – and particularly during pregnancy. Penicillin is a go-to therapy for many severe infections that can harm pregnant women and developing babies, such as:

• Group B streptococcal infections
• Certain sexually transmitted infections
• Pneumonia and other respiratory tract infections
• Postpartum endometriosis

Antibiotics related to penicillin are also the first line choice for preventing surgical infections in cesarean deliveries.

Patients who are labeled penicillin-allergic might have to try alternative antibiotics. This can result in extended illness and increased health care costs, which is already a concern for many patients.

It’s crucial that doctors do more to determine whether a patient-reported allergy is valid – the responsibility shouldn't lie solely on the patient. As such, I’ve invited my colleague, allergy and immunology expert David Khan, M.D., to discuss how patients and doctors can work together to pinpoint misdiagnosed penicillin allergies.

Did you have a penicillin reaction or a symptom of infection?

In 2017, the Centers for Disease Control and Prevention released a fact sheet titled “Is It Really a Penicillin Allergy?” The document touches on reactions of a penicillin allergy, many of which can also be symptoms of a serious infection. Such symptoms might include skin rashes or anaphylaxis (difficulty breathing or swallowing).

Sometimes patients tell us they are allergic to penicillin, based on some symptom that developed following a childhood exposure. And it’s understandable that a patient or parent might connect sudden, scary symptoms with the drug and not the disease. However, patients who’ve had such reactions in the past should have a thorough discussion with their doctor about their medical history as a first step to determining whether they’re truly allergic to penicillin. 

Why is getting an accurate medical history so important?

Discussing personal and family health information with patients during prenatal visits can reveal underlying conditions that might affect their current health and pregnancies. Also, it gives us an opportunity to improve future care by potentially correcting misdiagnosed penicillin allergies in their medical records.

Correction of an inaccurate penicillin allergy in medical records can result in substantial health care cost savings, due in part to effectiveness of penicillin as a first-line treatment. The largest study from Kaiser Permanente showed a reduction in costs of more than $1,900 per patient per year.

Many penicillin allergy labels can be removed by having a thorough medical history discussion with the doctor. However, sometimes verifying an allergy requires allergy testing. We developed a penicillin allergy testing service at Parkland Hospital in November 2014 to personalize the approach to each patient’s unique health history.

Does a penicillin allergy last forever?

According to the American Academy of Allergy, Asthma & Immunology, approximately 80 percent of patients with suspected penicillin allergies will test negative for reactions after 10 years of avoiding the drug.

A recent study at Parkland Hospital showed that 32 patients who were labeled penicillin-allergic in the past tested negative for the allergy during the trial. Afterwards they received a combined total of 111 courses of penicillin, and none had immediate reactions. This study and others confirm the low risk of re-acquiring a penicillin allergy.

What can patients take for infections if they are truly allergic?

Though misdiagnosis is common, 1% to 2% of patients truly are allergic to penicillin. We need to be particularly mindful in treating them if they acquire serious infections, particularly during pregnancy. Careful antibiotic use in pregnancy is important for a couple reasons. The first is safety – there are some antibiotics that can cause problems when they reach the fetus.

For example, tetracyclines work against certain infections and skin conditions but can discolor a baby’s teeth if the mother takes the drug during pregnancy. Some research suggests that certain types of antibiotics might be associated with a higher risk of miscarriage. However, we consider antibiotics generally safe for most women during pregnancy.

The second is effectiveness. Some antibiotics just do a better job of preventing or treating infection. Penicillin is highly effective against Group B streptococcal infections, which can easily pass from mothers to babies. Other antibiotics don’t work as well and can result in having to try several drugs before finding an effective treatment. 

A few closing thoughts

In a majority of cases, getting an accurate medical history and allergy testing can clear patients of being misdiagnosed with a penicillin allergy, opening the doors to better and less expensive care. Once cleared, these patients need to inform all of their providers to update their medical records so there is no question about their care in the future.

It might become a habit to say, “I’m allergic to penicillin” if a patient has been labeled as such for years. During prenatal care, patients and doctors should have many, many conversations about past and current health. If the doctor doesn’t ask about medication allergies or allergy testing, speak up – verifying a penicillin allergy can have long-term benefits for care beyond pregnancy.

Need to see an Ob/Gyn or get tested for a suspected penicillin allergy? Call 214-645-8300 or request an appointment online.