Guaifenesin is a synthetic version of the active compound in a tree-bark that has been used to liquefy mucus; it plays an active role in Mucinex™ and has been used to treat bronchial and sinus infections, colds, and allergies.

While searching for a less harmful medication for his Gout and Rheumatism patients, Dr. St. Amand found Guaifenesin to be effective. As an FMS sufferer himself, he theorized that Guaifenesin may be helpful with these patients as well - he was right. Although not a cure for Fibromyalgia, Dr. St. Amand found a way to reverse its debilitating symptoms. 

Used in Fibromyalgia patients at the proper dose, Guaifenesin removes phosphate from the kidney 6 times faster than without the medication. Used over time, guaifenesin removes the phosphate from these nodules, and symptoms decrease. Eventually, these debilitating symptoms disappear as the illness is reversed.

Source: FibromyalgiaTreatment.com