I think it’s important to keep in mind that sulpha antibiotics can cause rather severe (even fatal) skin reactions (an allergic response). These reactions may actually involve mast cells and the reactions include hives and other histamine sort of responses. Ugh. Because some of these reactions can be serious, it’s important to remember that you are likely allergic to sulpha antibiotics (and I also like to toss in, for those folks taking Diamox, that allergies to sulpha antibiotics do NOT cross over to Diamox — the chemical structure is different. Diamox does not contain the chain that involves supha allergies. whew.)