Guaifenesin for Fibromyalgia: Legit Treatment or Snake Oil?

by Karen Lee Richards Patient Advocate

You may have read some amazing stories of people who claim to have had a complete reversal of their fibromyalgia symptoms from taking something called guaifenesin.
You may also wonder why it is not prescribed more often if it works so well.
For almost two decades now, a controversy has raged over the guaifenesin protocol as a treatment for fibromyalgia.
Here is the story in a nutshell.

Guaifenesin is an expectorant primarily used to treat chest congestion.
It is found in some cough medicines and is the active ingredient in Mucinex.
It can be purchased over-the-counter, is often found in health-food stores, or may be prescribed by a physician.

Guaifenesin Protocol - The Background Story

The guaifenesin protocol for treating fibromyalgia was developed by Dr. R. Paul St. Amand in the early 1990s.
He believed that phosphate deposits throughout the body were the cause of FM and that FM symptoms could be reversed by removing excess phosphate from the body, which he claimed guaifenesin would do.

The protocol is not easy to follow - it involves much more than just taking a couple of guaifenesin tablets every day.
You're also instructed that you cannot eat or use any topical product that has salicylates in it because, according to Dr. St. Amand, salicylates block the effectiveness of the guaifenesin.
Since salicylates are found in many foods and most skin care products like lotions, shampoos, mouthwash, topical pain relievers, etc., it takes extraordinary vigilance to avoid them entirely.

The guaifenesin treatment plan is not for the faint-of-heart.
One of the key markers that indicates you have reached the optimum dosage is that your symptoms will get worse.
Of course, you are assured that if you continue to follow the protocol, you will gradually begin to have better days.

In 1995, Dr. Robert Bennett, a world-renowned fibromyalgia researcher and clinician, conducted a year-long study on guaifenesin for FM.
Dr. St. Amand was the technical advisor for the study.
The results of the study showed no significant FM symptom improvement nor was there a difference between those taking guaifenesin and those taking a placebo.

Dr. St. Amand now claims that the participants must have inadvertently used products with salicylates, which would make the study invalid.
Of course, Dr. Bennet disagrees.
And the controversy goes on.

Why Guaifenesin May Help Fibromyalgia

In the 20 years since Dr. St. Amand developed his theory, I don't know of a single study backing up his claim that phosphates cause fibromyalgia.
Nor am I aware of any evidence showing guaifenesin to be an effective method of ridding the body of excess phosphates.

There are, however, other reasons why guaifenesin may be helpful for some fibromyalgia patients.
I recently came across a very interesting article by Mark London, Systems Programmer/Analyst for the Plasma Science and Fusion Center at MIT.
He has done a very in-depth study of guaifenesin and the guaifenesin protocol.

While London finds nothing to validate Dr. St. Amand's phosphate theory, he has discovered that guaifenesin has several properties which could bring about some improvement in FM symptoms.
According to London, guaifenesin:

  • Has muscle relaxant properties.

  • May help reduce anxiety.

  • Can have an analgesic effect.

  • Is know to increases the analgesic effect of other pain relievers including acetaminophen and even opioids.

Although London's article is quite long and has a lot of scientific terminology, it is definitely worth reading if you have any interest in trying guaifenesin.
Here is a link to the article:
The Truths and Myths of the Use of Guaifenesin for Fibromyalgia

Guaifenesin Side Effects

Despite Dr. St. Amand's claim that guaifenesin has "no side effects," drug guides list common side effects as:

  • Dizziness

  • Headache

  • Rash

  • Nausea, vomiting, upset stomach

Under serious side effects is the possible formation of kidney stones.

There have been no studies on the effects of taking guaifenesin over a long period of time.
That's probably because it is mostly used as a cough treatment and is intended for short-term use.

Should You or Shouldn't You?

Personally, I'm not a big fan of the guaifenesin protocol - mainly because I don't think the theory has a solid scientific basis.
Also, I did try it several years ago but failed to see any change in my symptoms.

However, because of its analgesic and muscle-relaxing properties, it could be helpful for a certain percentage of FM patients.
Another plus is that it's inexpensive and as drugs go, has relatively few side effects.

I would encourage you to study the pros and cons carefully and discuss it with your doctor before making your decision.

  • London, M. (2010, December 5). "The truths and myths of the use of guaifenesin for fibromyalgia." Retrieved from
  • "The Guaifenesin Protocol." The Fibromyalgia Treatment Center.
Karen Lee Richards
Meet Our Writer
Karen Lee Richards

Karen is the co-founder of the National Fibromyalgia Association. She writes for HealthCentral as a patient expert for Pain Management.