Guaifenesin
"With moderate to severe fibromyalgia for 12 years I lost my career and lived in fear of having a life to avoid a flare-up.  I have tried every antidepressant, serotonin uptake inhibitor, pain medicine, anti-inflammatory.... you all know, with major side effects that only contributed to fibromyalgia symptoms.  March 2014 I got a cold and used Mucinex for the first time and could not believe the relief.  I have prayed for someone to invent a NEW MEDICINE for fibromyalgia that would work and it turned out this OLD MEDICINE has returned my life to me.  Thank God for Mucinex!"