I had been taking Cymbalta for fibromyalgia and back pain. Trust me, you do NOT want to quit cold turkey. Cymbalat is an antidepressant that builds up in your system over time. Quitting suddenly can cause you to go through serious withdrawals - emotions on edge, pain intesifies, weakness, illness, etc. I was out of pills and the pharmacy could not refill it for several days - it was pretty miserable and intense.
I had to stop taking it myself after building a tollerance to it. The best advice I can give you is to talk to your doctor before you make any changes. It is best to be weaned off overtime. Your doctor can prescribe smaller dosages and adjust the amount you take. For me the doctor lowered my dose then began to have me taking it every other day for awhile.