they do. I would suspect, if it’s that at all, that the ingredient causing the reaction is a binder or a surfactant that add to the whirlfloc to make it into a tablet or to make it dissolve more quickly.
I’ve heard that its just bicarb, although I can’t find an MSDS to confirm this. In which case it’s unlikely to be an allergy to that. As a matter of fact, carrageenan is much more likely to be the cause for an allergy than most of the ingredients that would be used in a tablet in general. Not to say that it’s not possible - just not likely.