Here is an extremely long and complex article, looks like it answers your question:
"A sulfite reaction is different from a sulfonamide allergy (a reaction to sulfa drugs) because sulfites and sulfonamides are entirely different chemicals and have unrelated mechanisms of reaction. A person sensitive to sulfites is no more likely to be allergic to sulfonamides than any other individual and vice versa. "
RockRose gave the technical answer. my DH, a pharmacist, has said that as well. however, it may be a coincidence, but it seems that some in my family have an allergy or sensitivity to anything "sulf.." Doesn't make sense to dh because they're chemically different. my mom is definitely allergic to Sulpha medications. she had a terrible reaction a few years back. She also has reactions to wines containing sulfites, and reacts to foods containing sulfites. i have never been on a sulfa medication, but i have the same exact reactions to certain foods as my mom. for example, literally one tiny sip of a wine (usually red) that has a lot of sulfites and i break out in crazy rashes all over my face. so i am going on the assumption that like my mom, i would most likely react to sulfa medications. not surprising, considering i'm pretty much a clone of my mom :)
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