A Wrong Allergy Label Turned One Childbirth Into a Cascade of Illness
The routine drug is safe in pregnancy and simple to time. The replacements are harder to dose and easier to regret.
Freakonomics Radio Network · Are You Really Allergic to Penicillin? (Update) | Freakonomics RadioShe arrived at the hospital ready to deliver a baby. On her chart were two words that would complicate everything that followed: penicillin allergy.
For most mothers in labor, the routine is simple. Many women carry a common vaginal bacterium called group B strep, which can harm a newborn during delivery. The standard protection is penicillin, a drug doctors regard as safe and effective in pregnancy. One dose on arrival, a second dose four hours later, and in most cases mother and baby do fine.
This mother could not follow that routine, because of the label. Instead of penicillin, the team gave her vancomycin, a substitute antibiotic. The dosing is far less forgiving, once every 12 hours. If the timing is off, as allergist Elena Resnik put it, "the baby can be considered inadequately treated," a judgment that can mean more antibiotics for the infant, and possibly a stay in the neonatal intensive care unit.
Then the substitutes began causing their own problems. The vancomycin brought on a flushing reaction in the mother known as red man syndrome, a reaction that, just as it sounds, leaves the body completely red and flushed and requires additional drugs to control. She then had a cesarean section, and the surgical wound became infected.
With that allergy label still on her record, doctors treated that wound infection with another alternative, clindamycin. From that drug she developed C. diff, a gut infection that itself required two weeks of oral vancomycin to treat. One precaution had become a chain: a different antibiotic, a reaction, an infection, another antibiotic, and another infection.
The chain finally broke in an allergy clinic. Allergist Elena Resnik tested the mother and was able to remove the penicillin allergy label altogether. Resnik said obstetricians now try to interrupt this pattern in advance, often telling patients with the label to get cleared before they get pregnant again, since testing is avoided during pregnancy itself for fear of triggering a severe reaction.
The vast majority of penicillin allergy labels are wrong, Resnik said, but in labor that label is not a footnote. It decides which drugs a doctor can reach for, and how much risk mother and child must absorb.
Questions people ask
How common is a false penicillin allergy?
About 10% of Americans carry a penicillin allergy label, but fewer than 1% are truly allergic. Most labels date to childhood, when a rash from the infection itself was mistaken for a drug reaction, and the label then stays on the chart for decades.
Can you get tested for penicillin allergy while pregnant?
Doctors usually will not test during pregnancy because even a small risk of a severe allergic reaction is unacceptable. Allergists instead recommend evaluation before a future pregnancy, often with skin testing followed by a supervised dose of amoxicillin.
What is red man syndrome?
It is a reaction most often linked to vancomycin given too quickly, with flushing and redness over the face, neck, and upper body. It is managed by slowing or stopping the infusion and giving other medications, and it signals that the substitute drug is already creating extra work.