Muscle Spasm
"I get muscle tightness and spasms often after workouts as a side effect of arthritis in my back &amp; neck (which was diagnosed for me in 2011). Flexeril was prescribed for this problem. It works great, but here is my feedback. First few times I took it, it knocked me out. Had to lay down &amp; sleep. Took awhile of taking it in smaller doses, where this effect went away. After 3 weeks of use, I started holding fluids really bad. So I no longer use it daily, only as desperately needed. Also causes constipation, so be prepared to add Fiber to your diet to help with that. When I do take it, I&#039;m able to work out the problem areas in my neck (which bothers me the most) with sports cream rub, while on the Flexeril. I can definitely recommend!"