Good evening. I have recently had a challenge test to sulfa and was extremely allergic to it after 4 hours. I have not had my follow up appt with my allergist yet but scheduled in two weeks. If I am allergic to sulfa, does that mean I must be careful with products containing sulfite, sulfate and sulfur? I know that I did use bactrim (which has the sulfa) before having the challenge test and that reaction is what prompted the challenge. How about Desonide cream which contains aluminum sulfate? Thank you in advance for responding to my question. Barbara