I think you are confused. There are various forms of sulfur.

Heavy metal chelators such as DMSA, DMPS and DHLA contain thiol--SH--groups.
http://lpi.oregonstate.edu/infocenter/othernuts/la/lastructure.html

I think you are revering to "sulfa drugs".

I'm fairly sure A. Cutler has previously commented in another detox group that the sulfa drug intolerance does not correlate with intolerance for the dithiol chelators. If you request I'll try to dig up the link to the post.