Dermatographic urticaria
Question:
10/3/2019
I have a teenager who has had amoxicillin for OM in 2014 and 2019 with dermatographia only (no rash or other systemic symptoms) a few days into the course of amoxicillin and lasting a few days after the course is completed. Interestingly, I found a comment on the Mayo Clinic website that states that dermatographia can follow a course of penicillin.
The SPT and IDs were negative, repeated twice, to PrePen and PenG. They obviously passed the oral challenge and is undergoing a five day course of amoxicillin to see how they do when not ill with amoxicillin, as urticaria can be associated with URIs and illness about 80% of the time in children. If the teen has dermatographia while well on amoxicillin, do I tell them to avoid with concerns of future risk of more severe reactions? I couldn't find any literature to support the Mayo Clinic website. Of note, the teen has some acquired idiopathic cold urticaria that started in 2017. Any input would be greatly appreciated.
Answer:
I was unable to find any clear cut data in the literature to answer your question. I have seen statements that dermatographia could occur after a course of antibiotics and if a PK test was done then the "recipient" could become dermatographia. I have never seen follow up data regarding antibiotic use in those patients. You have correctly identifies that the patient does not have IgE to PCN and has passed and oral challenge - all suggesting this is not IgE mediated process. Assuming the patient passes the prolonged challenges you are planning then I would say that patient is at no greater risk than the general population to use PCN in the future.
I hope this has been helpful.
Andrew Murphy, MD, FAAAAI