Do I Have An Allergy To Bactrim?

Our pharmacist answers the latest question regarding an allergy to Bactrim DS.

Sep 28, 2017

Andrew asked

I was born with a penicillin allergy. Every time that I have ever taken Bactrim DS for a UTI I have experienced itching in my genitals, but I just thought that was normal because the medicine was fighting off the bacteria in my nether regions. Was that an allergic reaction? Also, the past 2 times I have taken Bactrim DS I have developed a red rash on my face in the same places, what does that mean? Could I have been born with an allergy to Bactrim/sulfa medications?


Based on your description of the reaction you had, it certainly seems like an allergic reaction to me. Itching and rashy areas is certainly indicative of an allergy. While it isn't overly common, there are many people that have allergies to more than one drug class. I have never seen a cross sensitivity between penicillins and sulfa as they aren't chemically similar. You just may very well have multiple drug allergies. 

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