Guaifenesin is one such remedy whose name crops up often. Various studies have been done, the one below concludes: "The guaifenesin treatment also has major psychological benefits. The main one being the ability to picture one's pains in a more optimistic positive light. One's normal response to pain is to reduce activity, as pain is usually a signal to the body that an injury has occurred. Unfortunately, inactivity leads to unconditioned muscles, which is a major problem in many people with fibromyalgia. Constant pain and inactivity can then lead to other problems, such as myofascial pain. Gentle exercies and stretching can be beneficial to both problems. If one is assured that pain is not indicative of an injury, one is more likely to keep active. While on the guaifenesin treatment, pain can be attributed to the reversal process, and is thus thought to be a good sign. Pain is less frightening. Combining this outlook, with increased physical activity, and a possible neurological effect on pain and muscles, could lead to a significant improvement of fibromyalgia."
The author does warn that it does not work for everyone.
The Role of Guaifenesin in Fibromyalgia.: "The Truths and Myths of the use of Guaifenesin for Fibromyalgia (or) Guaifenesin: One Medicine, Several Effects by Mark London"