I am currently on Copaxone. I use the autoinjection to do the shots as I am a big whimp when it comes to needles. The nurse who showed me how to use the autoinjector told me to set the needle depth to 6mm. I kept it set to this depth for all injection sites. With this depth, I had all kinds of site reactions, from muscle spasms in my legs and arms to seriously huge and itchy welts on my "back-side" and stomach. I finally started to mess with needle depth, and have significantly reduced the severity of the site reactions. I now do legs and arms at 4mm and back-side and stomach at 8mm. Basically, if you are getting muscles spasms and cramping, I believe that the needles is going too deep. The itchy welts seem to be caused by the Copaxone not going in deep enough. Just my 2-cents. Hope this helps.