Pediatric Associates of the NW Blogs

Penicillin Allergy: New Testing Options on the Horizon!

M. Allison Baynham, MD
March 05, 2018 11:30AM

photo from Science News
photo from Science News

Penicillin, which includes amoxicillin, is one of the most commonly reported drug allergies. At Pediatric Associates of the Northwest, we see many parents who are concerned about an allergic reaction to amoxicillin in their babies.  However, many studies have confirmed that this is greatly over reported.  Where penicillin allergy is estimated to affect seven to ten percent of the population, testing of individuals who report a penicillin allergy shows that only one to eight percent of them are actually allergic. Why would this be?  There are many reasons.  Often, side effects are misreported as allergic symptoms (for example stomachache, diarrhea) or the patient has an underlying viral illness resulting in headache or rash that gets misdiagnosed as an allergic reaction.


We care about this because patients who have a reported history of penicillin allergy will often end up on stronger, more broad-spectrum antibiotics that may not be necessary.  One study showed that patients with an unverified penicillin allergy actually end up with longer hospital stays and increased rates of drug-resistant infections. 

There have been several studies recently looking at how to safely and quickly verify a penicillin allergy, especially in children.  There are blood tests, skin tests, and oral challenges (taking a dose of the medication in a monitored setting like a clinic or hospital) to observe for reactions available.  All approaches have their own risks and benefits, but overall research is showing that, for children, a step-wise oral challenge in a monitored setting may be the best way to test for penicillin allergy in a patient with a history of a low-risk reaction.

photo from Everydayfamily
photo from Everydayfamily

True allergic symptoms include hives, itching, vomiting, wheezing, difficulty breathing, airway swelling, low blood pressure, and lip or tongue swelling.  Hives, itching, nausea, and vomiting are considered low risk symptoms. Amoxicillin rashes can take three to six days to go away. Trouble breathing, airway involvement, or blood pressure changes are considered high-risk symptoms and are a concern for anaphylaxis, a severe life-threatening reaction.  Any patient who has a history of a high-risk symptom or a history of anaphylaxis would need to see an allergist for evaluation.


Our clinic is looking in to developing ways to offer a step-wise oral challenge for children with a history of low risk symptoms to help reduce the amount of patients who are falsely labeled with penicillin allergy and to avoid overprescribing of broad-spectrum antibiotics. We are working with local allergists to determine the safest method for your child for testing.  If you believe your child has a penicillin allergy and would like to discuss testing options, please make an appointment with your provider to discuss the best option for your family!



JAMA Pediatr. 2016;170(6):e160033. doi:10.1001/jamapediatrics.2016.0033

Published online April 4, 2016.

Vyles D, Adams J, Chiu A, et al. Allergy Testing in Children With Low-Risk

Penicillin Allergy Symptoms. Pediatrics. 2017;140(2):e20170471