No side effects yet (have just begun treatment) and no pain relief yet for severe arthritis in both wrists. I was taking Vioxx successfully with NO side effects and full pain relief. Then switched to Celebrex with almost full pain relief but NO side effects. Ultracet doesn't come close at this point. I'm not able to take naproxen in any form as it destroys my stomach (I'm prone to ulcers). I'm also taking Tylenol Arthritis formula. If Ultracet doesn't begin working soon -- or if Vioxx doesn't come back on the market I think I will have to shoot myself to put me out of my misery. I'm in unbearable pain!!!!