Allergic To Penicillin? There’s A 90% Chance That’s Not True
It’s scary to get an infection duringpregnancy. It’s even worse if a patient believes she’s allergic to the bestdrug to treat it.
But that’s the case for an estimated 10% ofthe 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 theirmedical records.
This isa serious health concern for all patients – and particularly during pregnancy. Penicillin is a go-to therapy for many severe infections that can harmpregnant women and developing babies, such as:
- Group B streptococcal infections
- Certain sexually transmitted infections
- Pneumonia and other respiratorytract infections
- Postpartum endometriosis
Antibiotics related to penicillin are also thefirst line choice for preventing surgical infections in cesarean deliveries.
Patients who are labeled penicillin-allergicmight have to try alternative antibiotics. This can result in extended illnessand increased health care costs, which is already a concern for many patients.
It’s crucial that doctors do more to determinewhether a patient-reported allergy is valid – the responsibility shouldn't liesolely on the patient. As such, I’ve invited my colleague, allergy andimmunology expert David Khan, M.D., to discuss how patients and doctors canwork together to pinpoint misdiagnosed penicillin allergies.
Did you have a penicillin reaction ora symptom of infection?
In 2017, the Centers for Disease Control andPrevention released a fact sheet titled “Is It Really a Penicillin Allergy?” Thedocument touches on reactions of a penicillin allergy, many of which can alsobe symptoms of a serious infection. Such symptoms might include skin rashes oranaphylaxis (difficulty breathing or swallowing).
Sometimes patients tell us they are allergic to penicillin, based on some symptom that developedfollowing a childhood exposure. And it’s understandable that a patient orparent 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 thoroughdiscussion with their doctor about their medical history as a first step to determiningwhether they’re truly allergic to penicillin.
Why is getting an accurate medicalhistory so important?
Discussing personal and family healthinformation with patients during prenatal visits can reveal underlyingconditions that might affect their current health and pregnancies. Also, itgives us an opportunity to improve future care by potentially correctingmisdiagnosed 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.
How does penicillin allergy testing work?
After a complete medical history, we consider one of two approaches to test for a true allergy.
Much like we do in other allergy testing scenarios, a healthcare provider will prick the skin or inject a small amount of penicillin into the skin and watch for a reaction. If a red or itchy bump arises, it’s likely the patient is allergic. However, most patients will have no reaction, allowing us to confidently determine they are extremely unlikely to be penicillin allergic.
Following a negative penicillin skin test, we administer a full dose of penicillin to confirm a patient is not allergic to penicillin. In some very low risk cases, we may proceed to penicillin challenge without prior skin tests.
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.