Duloxetine
"I have been using Duloxetine for  couple months for Fibromyalgia.  I didn't have any initial side effects.  It has helped me enormously with the muscle pain and spasms. The downside is it has lowered my libido,  I'm fatigued and have weight gain. As I am also menopausal it's a bit hard to tell what is causing some of the side effects.  The lowering of the libido is definitely a side effect of duloxetine. Not sure if I will continue on this medication."