"i was switched to effexor xr after 2 years of paxil. it worked wonderful for about 3 years. i was on 75mg and started to have uncontrollable movement with my one arm. talked to my doctor who said it was not the medicine. well after another year i was having the problem in my legs and both arms and could no longer sit or walk without frequent jerking. my doctor finally realized that it was a rare side effect of the medication from long term use and switched me to another. i still have the jerking at least 2 to 3 times a week. if you notice this problem at all you need to talk to your doctor immediately."