Is it the guaifenesin or the FMS causing the rash?
Biopsies of skin in 22 fibromyalgics reported in early 1998 showed disintegration of mast cells under the skin; these cells release histamine. It also showed the accumulation of immunoglobulin G in the dermis. These are the probable causes of the various rashes, hives, and itching we so frequently see in FM. There is no doubt that phosphates are excessive in the skin as well, but the reason for dermal malfunction is the same as in muscles, brain etc. The accumulated phosphate decreases energy formation, ATP. It is the same all over. Much of the body and its cells are in difficulty. Fibromyalgia can also cause itching, and the Guaifenesin will make it worse. The other thing you could do is changing your sheets. Sometimes they do not get rinsed completely in the laundry, being bulky, and soap remains behind. You may want to try changing detergents (unless you just did, which may be the problem) or at least double rinsing big loads. That is, of course, if the rash is not just plain old FM
