I am not referring to an adverse reaction or allergy. This is a painful muscular issue set off by taking any medication, doesn't matter what it is, but I can give a run down: wellbutrin, blood pressure meds, acid reflux meds, magic mouthwash, trazodone ~ anything taken brings on the reaction. Sometimes occur fast, within minutes, sometimes not until the next day. Even with only taking one medication, it does it. I have GI issues but would something in particular cause this problem? Which GI organs would cause such a fast reaction? Stomach or liver?