I had read that it could be a side effect. I had such bad muscle pain that I ended up losing a job over it; sitting at a desk 8 hours was unbearable regardless of all the NSAIDs & muscle relaxers I was popping, and doing exercises per a physical therapist every day! Not once did my doctor indicate it could possibly be a side effect of the SSRI. And it didn't go away instantly when I quit the drug, but it got SIGNIFICANTLY better over time and I don't have to take stuff for pain every day anymore!