Guaifenesin
ibromyalgia
"I agree it probably doesn't work for the reasons set forth by St.Amand, but it did work for me (complying with the salicylate ban) in the timescales he finds,  as follows: 



3 days of nothing 

Then 2.5 days of feeling great

Then 7 months of feeling worse than ever

Then roughly 2 years of feeling much much better, but eventually it tailed off to nothing.  Still the only effective FMS/CFS medicine I've tried except for LDN."