Guaifenesin and Fibromyalgia


Guaifenesin may not be well-known, but it is an ingredient used in many cough syrups to loosen mucus that is in the respiratory tract. For a number of years Los Angeles physician, R. Paul St. Amand, M.D., assistant clinical professor of medicine at Los Angeles Harbor/UCLA Hospital has promoted taking guiaifenesin as a natural treatment of fibromyalgia.

His claims are clear – that guaifenesin will relieve fibromyalgia symptoms by excreting harmful calcium phosphate deposits in muscles, tendons, joints, and other tissues, that are a result from defective kidney function. In fact, it has been reported that Amand has fibromyalgia himself and has since cured himself of all symptoms.

There has been one well-known study that has been undertaken to review the use of guaifenesin in fibromyalgia. The study was thorough, and was a yearlong, double-blinded, placebo-controlled investigation. Natural health expert Dr. Andrew Weil described the study, conducted by Robert M. Bennett, M.D., (now retired) professor of medicine and chairman of the Division of Arthritis and Rheumatic Diseases at Oregon Health & Science University, which was completed in 1996, as showing no difference between guaifenesin and placebo for fibromyalgia treatment - and no significant change in symptoms or in levels of phosphates.

He also notes that Bennett's study was criticized by guaifenesin proponents as being flawed because participants may have used topical products or products which contain salicylates which, supposedly are thought to interfere with guaifenesin. Weil disagrees with that assertion as well.

Guaifenesin is an over the counter drug, but that does not mean it does not have risks. For example, it may not be safe for use during pregnancy or breastfeeding, and may have sedative effects.


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Fibromyalgia is a prevalent condition that affects many people in the United States. Approximately 3.7 million Americans have Fibromyalgia. That is 1 in every 73 people.

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