It is well known that 9 of 10 Americans who believe they are allergic to penicillin are not allergic. It is also known that broad-spectrum antibiotics are not as effective as penicillin, and their use can increase antibiotic resistance. A new study being presented at this year’s virtual American College of Allergy, Asthma, and Immunology (ACAAI) Annual Scientific Meeting showed the majority of pregnant women with a penicillin allergy label who were tested were not allergic and could tolerate penicillin during labor.

“Of the 32 pregnant women we evaluated, 25 had skin testing for penicillin allergy, and all were negative,” says Benjamin Wang, MD, ACAAI member and author of the study. “Eight of the 25 patients had uncomplicated pregnancies and therefore had no need for penicillin during their pregnancy. Two of the pregnant women received antibiotics prior to completion of a graded oral challenge because of unexpected skin lacerations related to vaginal delivery. Thirteen tested positive for Group B Strep (GBS) and underwent both skin testing and an oral challenge, followed by receiving penicillin during labor.”

Only those pregnant women who tested positive for GBS or who needed penicillin underwent an oral amoxicillin challenge. GBS is a type of bacteria sometimes found in pregnant women. GBS usually does not cause health problems but can be harmful to newborns.

“Penicillin allergy testing is important for anyone who was given a penicillin allergy label as a child, and still carries it as an adult,” says allergist Mariana Castells, MD, PhD, chair of the ACAAI Task Force on Drug Allergy. “A pregnant woman with GBS may need penicillin for treatment. If she is labelled as allergic, she will be offered a less effective, and possibly more harmful antibiotic. It is important to have penicillin de-labeling ahead of the need for penicillin.”

An allergist can work with a patient to find out if they are truly allergic to penicillin, and, if so, to determine their treatment options. Patients who are not allergic will be able to use medications that are safer, often more effective, and less expensive, according to ACAAI.