I'm allergic to fortaz, presumably all the other penicillian drugs, but I haven't had the pleasure to find out just yet. I had a reaction back last time I was in the hospital a couple months ago and it was quite a show. I even got an audience. By the end of it I had drawn in all the floor nurses, a respirtory therapist, the oncall doctor, and probably a few others. I've never seen so many people gathered into one room. Aparantely it was the most dramatic reaction they'd seen in a while. I swelled up like a balloon, my chest got all tight, vomitted far beyond what I thought I had eaten. I was still itchy the next day.