"For Fibromyalgia:  I have been taking two 600 mg tabs per day of the 100% guafenesin Mucinex since June 2014. Previously was on Lyrica (I now have liver damage I think was caused from that and Cymbalta) which really didn&#039;t seem to help much. Can&#039;t claim to be totally pain free because it appears I have a &quot;weather&quot; body. Whenever a high pressure storm system comes in, my pain levels go up. I am convinced however that guafenesin therapy works. I have seen other websites that say it is only having a placebo effect, but then how do you explain those people who accidentally helped themselves stop fibro pain when they took it for sinus problems? I now have to be very careful what I take due to liver problems and guaf has no side effects... So? :)"