Thanks so much for your informative reply. I just checked, and the Mucinex I bought IS the extended release. Does Mucinex make a fast acting tablet? If not, where can I find it?
"I assume that guaifenesin is a prescription drug and am wondering if her doctor, who is a general practioner is knowledgeble enough to prescribe it for her if she asked him to."
Guaifenesin used to be available both over-the-counter (fast-acting) and as a prescription (slow-acting, extended release) until the FDA decided there's no reason to keep it as a prescription medication since there's never been a problem with it.
Previously, whenever doctors prescribed guaifenesin, it had to be the extended release version because drug coverage would not cover over the counter medications -- but only prescribed drugs. Therefore there was this bias towards the extended release version -- for patients with drug coverage and quite a number of fibromyalgics were on permanent disability. So when the extended release no longer was a prescription drug, everybody had to buy their own -- whether extended or fast acting, the latter being considerably cheaper. At that point, there was tremendous confusion because although guaifenesin is really a cheap generic, the process for making it extended release is patented -- and not guaifenesin itself.
Immunesupport.com and http://www.guailife.com/ are the cheapest, easily available sources I know of without any complications of pretending to make it rocket science or in need of a presciption. If somebody can figure out how to order and have it shipped from Canada, in bulk (powder) form they are really cheap -- about 1,000 capsules worth for $10. They make a profit on selling the gelatin caps to put them in. Their sites are not user-friendly.