More can be learned about the use of guaifenesin at several sites such as this one.
Guaifenesin can help with the following
Diagnosis and treatment of CFS and FN are combined in the use of the decongestant guaifenesin (often called “guai” by users). Dr. St. Amand in his book What Your Doctor May Not Tell You About Fibromyalgia gives an excellent presentation on the subject with full details of guai use. He does not distinguish between Chronic Fatigue Syndrome, Fibromyalgia, or Candida, using guai for them all. This protocol requires the careful avoidance of all salicylates and a hypoglycemic diet if low blood sugar is a factor. There are extensive web sites on its use.