I was only on the Duragesic patches for two weeks-during the worst ot the mucositis. Before the patches I had to apply lidocaine to the inside of my mouth, then swallow 4 tsp of Hydrocodone just to reduce the pain enough to sleep a couple of hours, or to drink some water or Ensure. The patch completely eliminated the need to use the lidocaine or hydrocodone. I don't know if it had any side effects, I was so out of it anyway during that time.