Most kids with penicillin allergies aren’t actually allergic

The Pediatric Insider

© 2017 Roy Benaroch, MD

It’s a common problem: an infant or child has a rash or another symptom while taking antibiotic, so he’s considered “allergic.” The chart is so marked, and the child isn’t allowed to take that antibiotic anymore. But a new study adds to growing evidence that many children thought to be allergic actually aren’t. They could take that same drug again, and they’d do fine.

This isn’t a minor issue. Second like drugs used when there’s a reported allergy tend to be less effective or more broad-spectrum, leading to more side effects. And some kinds end up with a whole lot of alleged allergies, making it difficult to treat them with anything.

In the current study, the authors looked at children (age 4 to 18) showing up to an Emergency Department with a history of any penicillin allergy (this includes amoxicillin, Augmentin, and other penicillins.) Parents were asked to fill out a questionnaire about their child’s previous reactions, and most of the common reactions reported were considered “low risk” for true allergy – symptoms like any rash (hives or not hives, any rash), itching, diarrhea, comiting, runny nose, nausea, cough, headache, dizziness, or allergy suspected based only on a family member being allergic. If a child’s symptoms were one or more of these items, they were considered “low risk” to be truly allergic. When 100 of these “low risk” patients had formal allergy testing, ALL of them tested negative. Not one of them was allergic to penicillin.

Reported “high risk” symptoms included facial or lip swelling, difficulty breathing, wheezing, throat swelling, skin blisters or peeling, or a drop in blood pressure. These children were not tested for penicillin allergy, and were presumed to be really allergic.

This was a small sample – despite their “100% not allergic” finding, I don’t think anyone’s prepared to say that all amoxicillin rashes can be disregarded as non allergic. But it’s clear that most children (and adults) labeled as penicillin or amoxicillin allergic are not allergic, and could safely try the medication again. If you or your child is thought to be allergic, talk with your doctor about the exact reaction, and see if either a rechallenge or a referral to an allergist would be a good idea.



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4 Comments on “Most kids with penicillin allergies aren’t actually allergic”

  1. Allison Says:


    So child had a “10 day rash” when on amoxicillin as an infant. Has subsequently showed allergic to many other allergens (tree nuts, all seasonal, most other airborn allergens) – allergic reaction is most commonly hives/rash. Showed allergic (hives) to keflex around age 13. Now 15 years old. Worth a retrial on the amoxicillin?


  2. dm Says:

    How does the questionnaire account for severe delayed reactions? My 1 year old had a delayed reaction (after 8 days of amoxicillin) that consisted of full-body hives, swelling and pain at the joints and lymph nodes (poor baby), and a very high fever. I was told never to give penicillin again by the pediatrician.


  3. Dr. Roy Says:

    Allison and dm, talk with your own docs about the exact circumstances to help decide if rechallenge or an allergy eval is a good idea. I’m not going to be giving any specific advice to any specific patients here. I just can’t know the whole story, and I’m (probably) not your doctor.


  4. Angela Says:

    Interesting. My oldest son (now 7) had a mild rash right after he finished a dose of amoxicillin. It was just a rash, I think maybe a little itchy. I may ask his doctor about this in the future.


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