"added deplin 15mg to 150 mg dose of wellbutrin when the wellbutrin no longer worked as well. it did help for a few days but then i developed severe muscle weakness, stiffness and pain particularly in my neck and shoulders. bad enough that i could not turn my head or look up or down without great discomfort. kind of felt like i had whiplash. i did some research and found that the muscle pain can be a side effect of both medications. i have not ever had this problem on wellbutrin alone, so i&#039;m inclined to think the deplin caused this. i quit taking both medications because i couldn&#039;t function with the pain and stiffness any longer and 2 days later the pain is still there but is slowly subsiding."