Bactrim and coughing up

I was given Bactrim after a laser procedure to my face. For the first seven days, my only symptom was a very red face which I unknowingly attributed to the laser procedure. On the eighth day, my face was very much improved in colour which I later realised was because I had accidently missed two doses of Bactrim. When I recommenced with the Bactrim the next morning, within a few hours my face was intensely itchy and red and I broke out in a rash all over my torso. At this point I became concerned and did some internet research, only to realise my symptoms were all Bactrim related. Apparently sulfite allergies are relatively common amongst the population, and I now know why I get a flushed face when I drink beer or wine.