For about 13 years I have worn a fentanyl patch, starting at 25 and now at 75mcg. For about 8 years I have had breakthrough pain at 48 hours so the dr. had to change the patch every 48 hrs. Now my insurance will only let me have 30 (not 45) patches/90day period. I also take Percocet 7.5/325 everyday. I have chronic pain from a MVA that was near fatal for me in 2001. Now the dr. has me changing the patch every 3 days and on days l and 2 I take 4 percocets and on day 3 I take 6 percocets. When I change the patch every 3 days how soon do I get the full pain relief from the fentanyl patch? Leceann