However, many argue that there is a lack of scientific evidence to support such a claim. In 1996, a double blinded and placebo controlled study was done. This study showed that phosphate levels and fibromyalgia symptoms were the same among individuals who administered guaifenesin and those who were given placebo.
Due to the risks and the lack of scientific research, you should talk to your doctor before you considering guaifenesin for fibromyalgia. Additionally, fibromyalgia patients who are pregnant and those who are trying to get pregnant must discuss with their doctor for alternative treatment. This is because guaifenesin can harm the development of the baby in the womb. Moreover, it is your doctor who determines the proper dosage, given your individual circumstances. The dosage ranges from 300 mg taken twice a day up to 2,600 mg once a day.