my doctor didnt tell me anything about different drug interactions to the fentanyl transdermal system. i was on here just looking around and seen that one major interaction was grapfruit and 12 hr cold medicine. so now i am wondering if there is an interaction between loratab/ hydrocodone 10mg. my doctor prescribed me the hydrocodone previously. the fentanyl is to be worn for 72 hrs. when it gets close to the end of the 72 hrs the pain becomes severe. so i was wondering if i can take a hydrocodone to ease the pain. so my question is, can i? or is there an interaction between the 2 medicines that would have bad results?